运行InstallShield安装包的问题 -
- ITeye博客
&&& 今天在遇到一个问题,就是在2003系统上运行InstallShield安装包时,弹出一个错误对话框,"An error (-04005)has occurred while running the setup",以前遇到这个问题就是删除C盘下Program Files 下的InstallShield Installation Information文件夹,但是发现这个机器上没有这个文件夹.
&&& 公司不能网上查资料,留下记录,晚上回去好好研究下!
&&& /kb
问题已经解决,解决方法:
1.打开控制面板。
2.添加或删除程序-&添加新程序-&从CD-ROM或软盘安装程序。
3.选择GTR安装包安装。
原因：与操作系统有关系。
wanglong1615
浏览: 20629 次
来自: 武汉
简洁明了！
说得不错！
重启！搞定
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Description说明
I get the fol ...db:: 4.34::Error while running MSDT Reporting on a Windows 2008 xp
Widget settings form goes hereSpring Quick Guide
Spring - Quick Guide
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Spring Framework - Overview
Spring is the most popular application development framework for enterprise Java. Millions of developers around the world use Spring Framework to create high performing, easily testable, and reusable code.
Spring framework is an open source Java platform. It was initially written by Rod Johnson and was first released under the Apache 2.0 license in June 2003.
Spring is lightweight when it comes to size and transparency. The basic version of Spring framework is around 2MB.
The core features of the Spring Framework can be used in developing any Java application, but there are extensions for building web applications on top of the Java EE platform. Spring framework targets to make J2EE development easier to use and promotes good programming practices by enabling a POJO-based programming model.
Benefits of Using the Spring Framework
Following is the list of few of the great benefits of using Spring Framework &
Spring enables developers to develop enterprise-class applications using POJOs. The benefit of using only POJOs is that you do not need an EJB container product such as an application server but you have the option of using only a robust servlet container such as Tomcat or some commercial product.
Spring is organized in a modular fashion. Even though the number of packages and classes are substantial, you have to worry only about the ones you need and ignore the rest.
Spring does not reinvent the wheel, instead it truly makes use of some of the existing technologies like several ORM frameworks, logging frameworks, JEE, Quartz and JDK timers, and other view technologies.
Testing an application written with Spring is simple because environment-dependent code is moved into this framework. Furthermore, by using JavaBeanstyle POJOs, it becomes easier to use dependency injection for injecting test data.
Spring's web framework is a well-designed web MVC framework, which provides a great alternative to web frameworks such as Struts or other over-engineered or less popular web frameworks.
Spring provides a convenient API to translate technology-specific exceptions (thrown by JDBC, Hibernate, or JDO, for example) into consistent, unchecked exceptions.
Lightweight IoC containers tend to be lightweight, especially when compared to EJB containers, for example. This is beneficial for developing and deploying applications on computers with limited memory and CPU resources.
Spring provides a consistent transaction management interface that can scale down to a local transaction (using a single database, for example) and scale up to global transactions (using JTA, for example).
Dependency Injection (DI)
The technology that Spring is most identified with is the Dependency Injection (DI) flavor of Inversion of Control. The Inversion of Control (IoC) is a general concept, and it can be expressed in many different ways. Dependency Injection is merely one concrete example of Inversion of Control.
When writing a complex Java application, application classes should be as independent as possible of other Java classes to increase the possibility to reuse these classes and to test them independently of other classes while unit testing. Dependency Injection helps in gluing these classes together and at the same time keeping them independent.
What is dependency injection exactly? Let's look at these two words separately. Here the dependency part translates into an association between two classes. For example, class A is dependent of class B. Now, let's look at the second part, injection. All this means is, class B will get injected into class A by the IoC.
Dependency injection can happen in the way of passing parameters to the constructor or by post-construction using setter methods. As Dependency Injection is the heart of Spring Framework, we will explain this concept in a separate chapter with relevant example.
Aspect Oriented Programming (AOP)
One of the key components of Spring is the Aspect Oriented Programming (AOP) framework. The functions that span multiple points of an application are called cross-cutting concerns and these cross-cutting concerns are conceptually separate from the application's business logic. There are various common good examples of aspects including logging, declarative transactions, security, caching, etc.
The key unit of modularity in OOP is the class, whereas in AOP the unit of modularity is the aspect. DI helps you decouple your application objects from each other, while AOP helps you decouple cross-cutting concerns from the objects that they affect.
The AOP module of Spring Framework provides an aspect-oriented programming implementation allowing you to define method-interceptors and pointcuts to cleanly decouple code that implements functionality that should be separated. We will discuss more about Spring AOP concepts in a separate chapter.
Spring Framework - Architecture
Spring could potentially be a one-stop shop for all your enterprise applications. However, Spring is modular, allowing you to pick and choose which modules are applicable to you, without having to bring in the rest. The following section provides details about all the modules available in Spring Framework.
The Spring Framework provides about 20 modules which can be used based on an application requirement.
Core Container
The Core Container consists of the Core, Beans, Context, and Expression Language modules the details of which are as follows &
The Core module provides the fundamental parts of the framework, including the IoC and Dependency Injection features.
The Bean module provides BeanFactory, which is a sophisticated implementation of the factory pattern.
The Context module builds on the solid base provided by the Core and Beans modules and it is a medium to access any objects defined and configured. The ApplicationContext interface is the focal point of the Context module.
The SpEL module provides a powerful expression language for querying and manipulating an object graph at runtime.
Data Access/Integration
The Data Access/Integration layer consists of the JDBC, ORM, OXM, JMS and Transaction modules whose detail is as follows &
The JDBC module provides a JDBC-abstraction layer that removes the need for tedious JDBC related coding.
The ORM module provides integration layers for popular object-relational mapping APIs, including JPA, JDO, Hibernate, and iBatis.
The OXM module provides an abstraction layer that supports Object/XML mapping implementations for JAXB, Castor, XMLBeans, JiBX and XStream.
The Java Messaging Service JMS module contains features for producing and consuming messages.
The Transaction module supports programmatic and declarative transaction management for classes that implement special interfaces and for all your POJOs.
The Web layer consists of the Web, Web-MVC, Web-Socket, and Web-Portlet modules the details of which are as follows &
The Web module provides basic web-oriented integration features such as multipart file-upload functionality and the initialization of the IoC container using servlet listeners and a web-oriented application context.
The Web-MVC module contains Spring's Model-View-Controller (MVC) implementation for web applications.
The Web-Socket module provides support for WebSocket-based, two-way communication between the client and the server in web applications.
The Web-Portlet module provides the MVC implementation to be used in a portlet environment and mirrors the functionality of Web-Servlet module.
Miscellaneous
There are few other important modules like AOP, Aspects, Instrumentation, Web and Test modules the details of which are as follows &
The AOP module provides an aspect-oriented programming implementation allowing you to define method-interceptors and pointcuts to cleanly decouple code that implements functionality that should be separated.
The Aspects module provides integration with AspectJ, which is again a powerful and mature AOP framework.
The Instrumentation module provides class instrumentation support and class loader implementations to be used in certain application servers.
The Messaging module provides support for STOMP as the WebSocket sub-protocol to use in applications. It also supports an annotation programming model for routing and processing STOMP messages from WebSocket clients.
The Test module supports the testing of Spring components with JUnit or TestNG frameworks.
Spring - Environment Setup
This chapter will guide you on how to prepare a development environment to start your work with Spring Framework. It will also teach you how to set up JDK, Tomcat and Eclipse on your machine before you set up Spring Framework &
Step 1 - Setup Java Development Kit (JDK)
You can download the latest version of SDK from Oracle's Java site &
You will find instructions for installing JDK in downloaded files, follow the given instructions to install and configure the setup. Finally set PATH and JAVA_HOME environment variables to refer to the directory that contains java and javac, typically java_install_dir/bin and java_install_dir respectively.
If you are running Windows and have installed the JDK in C:\jdk1.6.0_15, you would have to put the following line in your C:\autoexec.bat file.
set PATH=C:\jdk1.6.0_15\%PATH%
set JAVA_HOME=C:\jdk1.6.0_15
Alternatively, on Windows NT/2000/XP, you will have to right-click on My Computer, select Properties & Advanced & Environment Variables. Then, you will have to update the PATH value and click the OK button.
On Unix (Solaris, Linux, etc.), if the SDK is installed in /usr/local/jdk1.6.0_15 and you use the C shell, you will have to put the following into your .cshrc file.
setenv PATH /usr/local/jdk1.6.0_15/bin:$PATH
setenv JAVA_HOME /usr/local/jdk1.6.0_15
Alternatively, if you use an Integrated Development Environment (IDE) like Borland JBuilder, Eclipse, IntelliJ IDEA, or Sun ONE Studio, you will have to compile and run a simple program to confirm that the IDE knows where you have installed Java. Otherwise, you will have to carry out a proper setup as given in the document of the IDE.
Step 2 - Install Apache Common Logging API
You can download the latest version of Apache Commons Logging API from . Once you download the installation, unpack the binary distribution into a convenient location. For example, in C:\commons-logging-1.1.1 on Windows, or /usr/local/commons-logging-1.1.1 on Linux/Unix. This directory will have the following jar files and other supporting documents, etc.
Make sure you set your CLASSPATH variable on this directory properly otherwise you will face a problem while running your application.
Step 3 - Setup Eclipse IDE
All the examples in this tutorial have been written using Eclipse IDE. So we would suggest you should have the latest version of Eclipse installed on your machine.
To install Eclipse IDE, download the latest Eclipse binaries from . Once you download the installation, unpack the binary distribution into a convenient location. For example, in C:\eclipse on Windows, or /usr/local/eclipse on Linux/Unix and finally set PATH variable appropriately.
Eclipse can be started by executing the following commands on Windows machine, or you can simply double-click on eclipse.exe
%C:\eclipse\eclipse.exe
Eclipse can be started by executing the following commands on Unix (Solaris, Linux, etc.) machine &
$/usr/local/eclipse/eclipse
After a successful startup, if everything is fine then it should display the following result &
Step 4 - Setup Spring Framework Libraries
Now if everything is fine, then you can proceed to set up your Spring framework. Following are the simple steps to download and install the framework on your machine.
Make a choice whether you want to install Spring on Windows or Unix, and then proceed to the next step to download .zip file for Windows and .tz file for Unix.
Download the latest version of Spring framework binaries from .
At the time of developing this tutorial, spring-framework-4.1.6.RELEASE-dist.zip was downloaded on Windows machine. After the downloaded file was unzipped, it gives the following directory structure inside E:\spring.
You will find all the Spring libraries in the directory E:\spring\libs. Make sure you set your CLASSPATH variable on this directory properly otherwise you will face a problem while running your application. If you are using Eclipse, then it is not required to set CLASSPATH because all the setting will be done through Eclipse.
Once you are done with this last step, you are ready to proceed to your first Spring Example in the next chapter.
Spring - Hello World Example
Let us start actual programming with Spring Framework. Before you start writing your first example using Spring framework, you have to make sure that you have set up your Spring environment properly as explained in
Chapter. We also assume that you have a bit of working knowledge on Eclipse IDE.
Now let us proceed to write a simple Spring Application, which will print "Hello World!" or any other message based on the configuration done in Spring Beans Configuration file.
Step 1 - Create Java Project
The first step is to create a simple Java Project using Eclipse IDE. Follow the option File & New & Project and finally select Java Project wizard from the wizard list. Now name your project as HelloSpring using the wizard window as follows &
Once your project is created successfully, you will have the following content in your Project Explorer &
Step 2 - Add Required Libraries
As a second step let us add Spring Framework and common logging API libraries in our project. To do this, right-click on your project name HelloSpring
and then follow the following option available in the context menu & Build Path & Configure Build Path to display the Java Build Path window as follows &
Now use Add External JARs button available under the Libraries tab to add the following core JARs from Spring Framework and Common Logging installation directories &
commons-logging-1.1.1
spring-aop-4.1.6.RELEASE
spring-aspects-4.1.6.RELEASE
spring-beans-4.1.6.RELEASE
spring-context-4.1.6.RELEASE
spring-context-support-4.1.6.RELEASE
spring-core-4.1.6.RELEASE
spring-expression-4.1.6.RELEASE
spring-instrument-4.1.6.RELEASE
spring-instrument-tomcat-4.1.6.RELEASE
spring-jdbc-4.1.6.RELEASE
spring-jms-4.1.6.RELEASE
spring-messaging-4.1.6.RELEASE
spring-orm-4.1.6.RELEASE
spring-oxm-4.1.6.RELEASE
spring-test-4.1.6.RELEASE
spring-tx-4.1.6.RELEASE
spring-web-4.1.6.RELEASE
spring-webmvc-4.1.6.RELEASE
spring-webmvc-portlet-4.1.6.RELEASE
spring-websocket-4.1.6.RELEASE
Step 3 - Create Source Files
Now let us create actual source files under the HelloSpring project. First we need to create a package called com.tutorialspoint. To do this, right click on src in package explorer section and follow the option & New & Package.
Next we will create HelloWorld.java and MainApp.java files under the com.tutorialspoint package.
Here is the content of HelloWorld.java file &
package com.
public class HelloWorld {
public void setMessage(String message){
this.message
public void getMessage(){
System.out.println("Your Message : " + message);
Following is the content of the second file MainApp.java &
package com.
import org.springframework.context.ApplicationC
import org.springframework.context.support.ClassPathXmlApplicationC
public class MainApp {
public static void main(String[] args) {
ApplicationContext context = new ClassPathXmlApplicationContext("Beans.xml");
HelloWorld obj = (HelloWorld) context.getBean("helloWorld");
obj.getMessage();
Following two important points are to be noted about the main program &
The first step is to create an application context where we used framework API ClassPathXmlApplicationContext(). This API loads beans configuration file and eventually based on the provided API, it takes care of creating and initializing all the objects, i.e. beans mentioned in the configuration file.
The second step is used to get the required bean using getBean() method of the created context. This method uses bean ID to return a generic object, which finally can be casted to the actual object. Once you have an object, you can use this object to call any class method.
Step 4 - Create Bean Configuration File
You need to create a Bean Configuration file which is an XML file and acts as a cement that glues the beans, i.e. the classes together. This file needs to be created under the src directory as shown in the following screenshot &
Usually developers name this file as Beans.xml, but you are independent to choose any name you like. You have to make sure that this file is available in CLASSPATH and use the same name in the main application while creating an application context as shown in MainApp.java file.
The Beans.xml is used to assign unique IDs to different beans and to control the creation of objects with different values without impacting any of the Spring source files. For example, using the following file you can pass any value for "message" variable and you can print different values of message without impacting HelloWorld.java and MainApp.java files. Let us see how it works &
&?xml version = "1.0" encoding = "UTF-8"?&
&beans xmlns = "http://www.springframework.org/schema/beans"
xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation = "http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd"&
&bean id = "helloWorld" class = "com.tutorialspoint.HelloWorld"&
&property name = "message" value = "Hello World!"/&
When Spring application gets loaded into the memory, Framework makes use of the above configuration file to create all the beans defined and assigns them a unique ID as defined in &bean& tag. You can use &property& tag to pass the values of different variables used at the time of object creation.
Step 5 - Running the Program
Once you are done with creating the source and beans configuration files, you are ready for this step, which is compiling and running your program. To do this, keep MainApp.Java file tab active and use either Run option available in the Eclipse IDE or use Ctrl + F11 to compile and run your MainApp application. If everything is fine with your application, this will print the following message in Eclipse IDE's console &
Your Message : Hello World!
Congratulations, you have successfully created your first Spring Application. You can see the flexibility of the above Spring application by changing the value of "message" property and keeping both the source files unchanged.
Spring - IoC Containers
The Spring container is at the core of the Spring Framework. The container will create the objects, wire them together, configure them, and manage their complete life cycle from creation till destruction. The Spring container uses DI to manage the components that make up an application. These objects are called Spring Beans, which we will discuss in the next chapter.
The container gets its instructions on what objects to instantiate, configure, and assemble by reading the configuration metadata provided. The configuration metadata can be represented either by XML, Java annotations, or Java code. The following diagram represents a high-level view of how Spring works. The Spring IoC container makes use of Java POJO classes and configuration metadata to produce a fully configured and executable system or application.
Spring provides the following two distinct types of containers.
Container & Description
This is the simplest container providing the basic support for DI and is defined by the org.springframework.beans.factory.BeanFactory interface. The BeanFactory and related interfaces, such as BeanFactoryAware, InitializingBean, DisposableBean, are still present in Spring for the purpose of backward compatibility with a large number of third-party frameworks that integrate with Spring.
This container adds more enterprise-specific functionality such as the ability to resolve textual messages from a properties file and the ability to publish application events to interested event listeners. This container is defined by the org.springframework.context.ApplicationContext interface.
The ApplicationContext container includes all functionality of the BeanFactorycontainer, so it is generally recommended over BeanFactory. BeanFactory can still be used for lightweight applications like mobile devices or applet-based applications where data volume and speed is significant.
Spring - Bean Definition
The objects that form the backbone of your application and that are managed by the Spring IoC container are called beans. A bean is an object that is instantiated, assembled, and otherwise managed by a Spring IoC container. These beans are created with the configuration metadata that you supply to the container. For example, in the form of XML &bean/& definitions which you have already seen in the previous chapters.
Bean definition contains the information called configuration metadata, which is needed for the container to know the following &
How to create a bean
Bean's lifecycle details
Bean's dependencies
All the above configuration metadata translates into a set of the following properties that make up each bean definition.
Properties & Description
This attribute is mandatory and specifies the bean class to be used to create the bean.
This attribute specifies the bean identifier uniquely. In XMLbased configuration metadata, you use the id and/or name attributes to specify the bean identifier(s).
This attribute specifies the scope of the objects created from a particular bean definition and it will be discussed in bean scopes chapter.
constructor-arg
This is used to inject the dependencies and will be discussed in subsequent chapters.
properties
This is used to inject the dependencies and will be discussed in subsequent chapters.
autowiring mode
This is used to inject the dependencies and will be discussed in subsequent chapters.
lazy-initialization mode
A lazy-initialized bean tells the IoC container to create a bean instance when it is first requested, rather than at the startup.
initialization method
A callback to be called just after all necessary properties on the bean have been set by the container. It will be discussed in bean life cycle chapter.
destruction method
A callback to be used when the container containing the bean is destroyed. It will be discussed in bean life cycle chapter.
Spring Configuration Metadata
Spring IoC container is totally decoupled from the format in which this configuration metadata is actually written. Following are the three important methods to provide configuration metadata to the Spring Container &
XML based configuration file.
Annotation-based configuration
Java-based configuration
You already have seen how XML-based configuration metadata is provided to the container, but let us see another sample of XML-based configuration file with different bean definitions including lazy initialization, initialization method, and destruction method &
&?xml version = "1.0" encoding = "UTF-8"?&
&beans xmlns = "http://www.springframework.org/schema/beans"
xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation = "http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd"&
&!-- A simple bean definition --&
&bean id = "..." class = "..."&
&!-- collaborators and configuration for this bean go here --&
&!-- A bean definition with lazy init set on --&
&bean id = "..." class = "..." lazy-init = "true"&
&!-- collaborators and configuration for this bean go here --&
&!-- A bean definition with initialization method --&
&bean id = "..." class = "..." init-method = "..."&
&!-- collaborators and configuration for this bean go here --&
&!-- A bean definition with destruction method --&
&bean id = "..." class = "..." destroy-method = "..."&
&!-- collaborators and configuration for this bean go here --&
&!-- more bean definitions go here --&
You can check
to understand how to define, configure and create Spring Beans.
We will discuss about Annotation Based Configuration in a separate chapter. It is intentionally discussed in a separate chapter as we want you to grasp a few other important Spring concepts, before you start programming with Spring Dependency Injection with Annotations.
Spring - Bean Scopes
When defining a &bean&
you have the option of declaring a scope for that bean. For example, to force Spring to produce a new bean instance each time one is needed, you should declare the bean's scope attribute to be prototype. Similarly, if you want Spring to return the same bean instance each time one is needed, you should declare the bean's scope attribute to be singleton.
The Spring Framework supports the following five scopes, three of which are available only if you use a web-aware ApplicationContext.
Scope & Description
This scopes the bean definition to a single instance per Spring IoC container (default).
This scopes a single bean definition to have any number of object instances.
This scopes a bean definition to an HTTP request. Only valid in the context of a web-aware Spring ApplicationContext.
This scopes a bean definition to an HTTP session. Only valid in the context of a web-aware Spring ApplicationContext.
global-session
This scopes a bean definition to a global HTTP session. Only valid in the context of a web-aware Spring ApplicationContext.
In this chapter, we will discuss about the first two scopes and the remaining three will be discussed when we discuss about web-aware Spring ApplicationContext.
The singleton scope
If a scope is set to singleton, the Spring IoC container creates exactly one instance of the object defined by that bean definition. This single instance is stored in a cache of such singleton beans, and all subsequent requests and references for that named bean return the cached object.
The default scope is always singleton. However, when you need one and only one instance of a bean, you can set the scope
property to singleton in the bean configuration file, as shown in the following code snippet &
&!-- A bean definition with singleton scope --&
&bean id = "..." class = "..." scope = "singleton"&
&!-- collaborators and configuration for this bean go here --&
Let us have a working Eclipse IDE in place and take the following steps to create a Spring application &
Description
Create a project with a name SpringExample and create a package com.tutorialspoint under the src folder in the created project.
Add required Spring libraries using Add External JARs option as explained in the Spring Hello World Example chapter.
Create Java classes HelloWorld and MainApp under the com.tutorialspoint package.
Create Beans configuration file Beans.xml under the src folder.
The final step is to create the content of all the Java files and Bean Configuration file and run the application as explained below.
Here is the content of HelloWorld.java file &
package com.
public class HelloWorld {
public void setMessage(String message){
this.message
public void getMessage(){
System.out.println("Your Message : " + message);
Following is the content of the MainApp.java file &
package com.
import org.springframework.context.ApplicationC
import org.springframework.context.support.ClassPathXmlApplicationC
public class MainApp {
public static void main(String[] args) {
ApplicationContext context = new ClassPathXmlApplicationContext("Beans.xml");
HelloWorld objA = (HelloWorld) context.getBean("helloWorld");
objA.setMessage("I&m object A");
objA.getMessage();
HelloWorld objB = (HelloWorld) context.getBean("helloWorld");
objB.getMessage();
Following is the configuration file Beans.xml required for singleton scope &
&?xml version = "1.0" encoding = "UTF-8"?&
&beans xmlns = "http://www.springframework.org/schema/beans"
xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation = "http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd"&
&bean id = "helloWorld" class = "com.tutorialspoint.HelloWorld" scope = "singleton"&
Once you are done creating the source and bean configuration files, let us run the application. If everything is fine with your application, it will print the following message &
Your Message : I&m object A
Your Message : I&m object A
The prototype scope
If the scope is set to prototype, the Spring IoC container creates a new bean instance of the object every time a request for that specific bean is made. As a rule, use the prototype scope for all state-full beans and the singleton scope for stateless beans.
To define a prototype scope, you can set the scope property to prototype in the bean configuration file, as shown in the following code snippet &
&!-- A bean definition with singleton scope --&
&bean id = "..." class = "..." scope = "prototype"&
&!-- collaborators and configuration for this bean go here --&
Let us have working Eclipse IDE in place and follow the following steps to create a Spring application &
Description
Create a project with a name SpringExample and create a package com.tutorialspoint under the src folder in the created project.
Add required Spring libraries using Add External JARs option as explained in the Spring Hello World Example chapter.
Create Java classes HelloWorld and MainApp under the com.tutorialspoint package.
Create Beans configuration file Beans.xml under the src folder.
The final step is to create the content of all the Java files and Bean Configuration file and run the application as explained below.
Here is the content of HelloWorld.java file
package com.
public class HelloWorld {
public void setMessage(String message){
this.message
public void getMessage(){
System.out.println("Your Message : " + message);
Following is the content of the MainApp.java file &
package com.
import org.springframework.context.ApplicationC
import org.springframework.context.support.ClassPathXmlApplicationC
public class MainApp {
public static void main(String[] args) {
ApplicationContext context = new ClassPathXmlApplicationContext("Beans.xml");
HelloWorld objA = (HelloWorld) context.getBean("helloWorld");
objA.setMessage("I&m object A");
objA.getMessage();
HelloWorld objB = (HelloWorld) context.getBean("helloWorld");
objB.getMessage();
Following is the configuration file Beans.xml required for prototype scope &
&?xml version = "1.0" encoding = "UTF-8"?&
&beans xmlns = "http://www.springframework.org/schema/beans"
xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation = "http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd"&
&bean id = "helloWorld" class = "com.tutorialspoint.HelloWorld" scope = "prototype"&
Once you are done creating the source and bean configuration files, let us run the application. If everything is fine with your application, it will print the following message &
Your Message : I&m object A
Your Message : null
Spring - Bean Life Cycle
The life cycle of a Spring bean is easy to understand. When a bean is instantiated, it may be required to perform some initialization to get it into a usable state. Similarly, when the bean is no longer required and is removed from the container, some cleanup may be required.
Though, there are lists of the activities that take place behind the scene between the time of bean Instantiation and its destruction, this chapter will discuss only two important bean life cycle callback methods, which are required at the time of bean initialization and its destruction.
To define setup and teardown for a bean, we simply declare the &bean& with initmethod and/or destroy-method parameters. The init-method attribute specifies a method that is to be called on the bean immediately upon instantiation. Similarly, destroymethod specifies a method that is called just before a bean is removed from the container.
Initialization callbacks
The org.springframework.beans.factory.InitializingBean interface specifies a single method &
void afterPropertiesSet() throws E
Thus, you can simply implement the above interface and initialization work can be done inside afterPropertiesSet() method as follows &
public class ExampleBean implements InitializingBean {
public void afterPropertiesSet() {
// do some initialization work
In the case of XML-based configuration metadata, you can use the init-method attribute to specify the name of the method that has a void no-argument signature. For example &
&bean id = "exampleBean" class = "examples.ExampleBean" init-method = "init"/&
Following is the class definition &
public class ExampleBean {
public void init() {
// do some initialization work
Destruction callbacks
The org.springframework.beans.factory.DisposableBean interface specifies a single method &
void destroy() throws E
Thus, you can simply implement the above interface and finalization work can be done inside destroy() method as follows &
public class ExampleBean implements DisposableBean {
public void destroy() {
// do some destruction work
In the case of XML-based configuration metadata, you can use the destroy-method attribute to specify the name of the method that has a void no-argument signature. For example &
&bean id = "exampleBean" class = "examples.ExampleBean" destroy-method = "destroy"/&
Following is the class definition &
public class ExampleBean {
public void destroy() {
// do some destruction work
If you are using Spring's IoC container in a non-web app for example, in a rich client desktop environment, you register a shutdown hook with the JVM. Doing so ensures a graceful shutdown and calls the relevant destroy methods on your singleton beans so that all resources are released.
It is recommended that you do not use the InitializingBean or DisposableBean callbacks, because XML configuration gives much flexibility in terms of naming your method.
Let us have a working Eclipse IDE in place and take the following steps to create a Spring application &
Description
Create a project with a name SpringExample and create a package com.tutorialspoint under the src folder in the created project.
Add required Spring libraries using Add External JARs option as explained in the Spring Hello World Example chapter.
Create Java classes HelloWorld and MainApp under the com.tutorialspoint package.
Create Beans configuration file Beans.xml under the src folder.
The final step is to create the content of all the Java files and Bean Configuration file and run the application as explained below.
Here is the content of HelloWorld.java file &
package com.
public class HelloWorld {
public void setMessage(String message){
this.message =
public void getMessage(){
System.out.println("Your Message : " + message);
public void init(){
System.out.println("Bean is going through init.");
public void destroy() {
System.out.println("Bean will destroy now.");
Following is the content of the MainApp.java file. Here you need to register a shutdown hook registerShutdownHook() method that is declared on the AbstractApplicationContext class. This will ensure a graceful shutdown and call the relevant destroy methods.
package com.
import org.springframework.context.support.AbstractApplicationC
import org.springframework.context.support.ClassPathXmlApplicationC
public class MainApp {
public static void main(String[] args) {
AbstractApplicationContext context = new ClassPathXmlApplicationContext("Beans.xml");
HelloWorld obj = (HelloWorld) context.getBean("helloWorld");
obj.getMessage();
context.registerShutdownHook();
Following is the configuration file Beans.xml required for init and destroy methods &
&?xml version = "1.0" encoding = "UTF-8"?&
&beans xmlns = "http://www.springframework.org/schema/beans"
xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation = "http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd"&
&bean id = "helloWorld" class = "com.tutorialspoint.HelloWorld" init-method = "init"
destroy-method = "destroy"&
&property name = "message" value = "Hello World!"/&
Once you are done creating the source and bean configuration files, let us run the application. If everything is fine with your application, it will print the following message &
Bean is going through init.
Your Message : Hello World!
Bean will destroy now.
Default initialization and destroy methods
If you have too many beans having initialization and/or destroy methods with the same name, you don't need to declare init-method and destroy-method on each individual bean. Instead, the framework provides the flexibility to configure such situation using default-init-method and default-destroy-method attributes on the &beans& element as follows &
&beans xmlns = "http://www.springframework.org/schema/beans"
xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation = "http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd"
default-init-method = "init"
default-destroy-method = "destroy"&
&bean id = "..." class = "..."&
&!-- collaborators and configuration for this bean go here --&
Spring - Bean Post Processors
The BeanPostProcessor interface defines callback methods that you can implement to provide your own instantiation logic, dependency-resolution logic, etc. You can also implement some custom logic after the Spring container finishes instantiating, configuring, and initializing a bean by plugging in one or more BeanPostProcessor implementations.
You can configure multiple BeanPostProcessor interfaces and you can control the order in which these BeanPostProcessor interfaces execute by setting the order property provided the BeanPostProcessor implements the Ordered interface.
The BeanPostProcessors operate on bean (or object) instances, which means that the Spring IoC container instantiates a bean instance and then BeanPostProcessor interfaces do their work.
An ApplicationContext automatically detects any beans that are defined with the implementation of the BeanPostProcessor interface and registers these beans as postprocessors, to be then called appropriately by the container upon bean creation.
The following examples show how to write, register, and use BeanPostProcessors in the context of an ApplicationContext.
Let us have a working Eclipse IDE in place and take the following steps to create a Spring application &
Description
Create a project with a name SpringExample and create a package com.tutorialspoint under the src folder in the created project.
Add required Spring libraries using Add External JARs option as explained in the Spring Hello World Example chapter.
Create Java classes HelloWorld, InitHelloWorld and MainApp under the com.tutorialspoint package.
Create Beans configuration file Beans.xml under the src folder.
The final step is to create the content of all the Java files and Bean Configuration file and run the application as explained below.
Here is the content of HelloWorld.java file &
package com.
public class HelloWorld {
public void setMessage(String message){
this.message
public void getMessage(){
System.out.println("Your Message : " + message);
public void init(){
System.out.println("Bean is going through init.");
public void destroy(){
System.out.println("Bean will destroy now.");
This is a very basic example of implementing BeanPostProcessor, which prints a bean name before and after initialization of any bean. You can implement more complex logic before and after instantiating a bean because you have access on bean object inside both the post processor methods.
Here is the content of InitHelloWorld.java file &
package com.
import org.springframework.beans.factory.config.BeanPostP
import org.springframework.beans.BeansE
public class InitHelloWorld implements BeanPostProcessor {
public Object postProcessBeforeInitialization(Object bean, String beanName)
throws BeansException {
System.out.println("BeforeInitialization : " + beanName);
// you can return any other object as well
public Object postProcessAfterInitialization(Object bean, String beanName)
throws BeansException {
System.out.println("AfterInitialization : " + beanName);
// you can return any other object as well
Following is the content of the MainApp.java file. Here you need to register a shutdown hook registerShutdownHook() method that is declared on the AbstractApplicationContext class. This will ensures a graceful shutdown and calls the relevant destroy methods.
package com.
import org.springframework.context.support.AbstractApplicationC
import org.springframework.context.support.ClassPathXmlApplicationC
public class MainApp {
public static void main(String[] args) {
AbstractApplicationContext context = new ClassPathXmlApplicationContext("Beans.xml");
HelloWorld obj = (HelloWorld) context.getBean("helloWorld");
obj.getMessage();
context.registerShutdownHook();
Following is the configuration file Beans.xml required for init and destroy methods &
&?xml version = "1.0" encoding = "UTF-8"?&
&beans xmlns = "http://www.springframework.org/schema/beans"
xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation = "http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd"&
&bean id = "helloWorld" class = "com.tutorialspoint.HelloWorld"
init-method = "init" destroy-method = "destroy"&
&property name = "message" value = "Hello World!"/&
&bean class = "com.tutorialspoint.InitHelloWorld" /&
Once you are done with creating the source and bean configuration files, let us run the application. If everything is fine with your application, it will print the following message &
BeforeInitialization : helloWorld
Bean is going through init.
AfterInitialization : helloWorld
Your Message : Hello World!
Bean will destroy now.
Spring - Bean Definition Inheritance
A bean definition can contain a lot of configuration information, including constructor arguments, property values, and container-specific information such as initialization method, static factory method name, and so on.
A child bean definition inherits configuration data from a parent definition. The child definition can override some values, or add others, as needed.
Spring Bean definition inheritance has nothing to do with Java class inheritance but the inheritance concept is same. You can define a parent bean definition as a template and other child beans can inherit the required configuration from the parent bean.
When you use XML-based configuration metadata, you indicate a child bean definition by using the parent attribute, specifying the parent bean as the value of this attribute.
Let us have a working Eclipse IDE in place and take the following steps to create a Spring application &
Description
Create a project with a name SpringExample and create a package com.tutorialspoint under the src folder in the created project.
Add required Spring libraries using Add External JARs option as explained in the Spring Hello World Example chapter.
Create Java classes HelloWorld, HelloIndia and MainApp under the com.tutorialspoint package.
Create Beans configuration file Beans.xml under the src folder.
The final step is to create the content of all the Java files and Bean Configuration file and run the application as explained below.
Following is the configuration file Beans.xml where we defined "helloWorld" bean which has two properties message1 and message2. Next "helloIndia" bean has been defined as a child of "helloWorld" bean by using parent attribute. The child bean inherits message2 property as is, and overrides message1 property and introduces one more property message3.
&?xml version = "1.0" encoding = "UTF-8"?&
&beans xmlns = "http://www.springframework.org/schema/beans"
xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation = "http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd"&
&bean id = "helloWorld" class = "com.tutorialspoint.HelloWorld"&
&property name = "message1" value = "Hello World!"/&
&property name = "message2" value = "Hello Second World!"/&
&bean id =" helloIndia" class = "com.tutorialspoint.HelloIndia" parent = "helloWorld"&
&property name = "message1" value = "Hello India!"/&
&property name = "message3" value = "Namaste India!"/&
Here is the content of HelloWorld.java file &
package com.
public class HelloWorld {
private String message1;
private String message2;
public void setMessage1(String message){
this.message1 =
public void setMessage2(String message){
this.message2 =
public void getMessage1(){
System.out.println("World Message1 : " + message1);
public void getMessage2(){
System.out.println("World Message2 : " + message2);
Here is the content of HelloIndia.java file &
package com.
public class HelloIndia {
private String message1;
private String message2;
private String message3;
public void setMessage1(String message){
this.message1 =
public void setMessage2(String message){
this.message2 =
public void setMessage3(String message){
this.message3 =
public void getMessage1(){
System.out.println("India Message1 : " + message1);
public void getMessage2(){
System.out.println("India Message2 : " + message2);
public void getMessage3(){
System.out.println("India Message3 : " + message3);
Following is the content of the MainApp.java file &
package com.
import org.springframework.context.ApplicationC
import org.springframework.context.support.ClassPathXmlApplicationC
public class MainApp {
public static void main(String[] args) {
ApplicationContext context = new ClassPathXmlApplicationContext("Beans.xml");
HelloWorld objA = (HelloWorld) context.getBean("helloWorld");
objA.getMessage1();
objA.getMessage2();
HelloIndia objB = (HelloIndia) context.getBean("helloIndia");
objB.getMessage1();
objB.getMessage2();
objB.getMessage3();
Once you are done creating the source and bean configuration files, let us run the application. If everything is fine with your application, it will print the following message &
World Message1 : Hello World!
World Message2 : Hello Second World!
India Message1 : Hello India!
India Message2 : Hello Second World!
India Message3 : Namaste India!
If you observed here, we did not pass message2 while creating "helloIndia" bean, but it got passed because of Bean Definition Inheritance.
Bean Definition Template
You can create a Bean definition template, which can be used by other child bean definitions without putting much effort. While defining a Bean Definition Template, you should not specify the class attribute and should specify abstract
attribute and should specify the abstract attribute with a value of true as shown in the following code snippet &
&?xml version = "1.0" encoding = "UTF-8"?&
&beans xmlns = "http://www.springframework.org/schema/beans"
xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation = "http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd"&
&bean id = "beanTeamplate" abstract = "true"&
&property name = "message1" value = "Hello World!"/&
&property name = "message2" value = "Hello Second World!"/&
&property name = "message3" value = "Namaste India!"/&
&bean id = "helloIndia" class = "com.tutorialspoint.HelloIndia" parent = "beanTeamplate"&
&property name = "message1" value = "Hello India!"/&
&property name = "message3" value = "Namaste India!"/&
The parent bean cannot be instantiated on its own because it is incomplete, and it is also explicitly marked as abstract. When a definition is abstract like this, it is usable only as a pure template bean definition that serves as a parent definition for child definitions.
Spring - Dependency Injection
Every Java-based application has a few objects that work together to present what the end-user sees as a working application. When writing a complex Java application, application classes should be as independent as possible of other Java classes to increase the possibility to reuse these classes and to test them independently of other classes while unit testing. Dependency Injection (or sometime called wiring) helps in gluing these classes together and at the same time keeping them independent.
Consider you have an application which has a text editor component and you want to provide a spell check. Your standard code would look something like this &
public class TextEditor {
private SpellChecker spellC
public TextEditor() {
spellChecker = new SpellChecker();
What we've done here is, create a dependency between the TextEditor and the SpellChecker. In an inversion of control scenario, we would instead do something like this &
public class TextEditor {
private SpellChecker spellC
public TextEditor(SpellChecker spellChecker) {
this.spellChecker = spellC
Here, the TextEditor should not worry about SpellChecker implementation. The SpellChecker will be implemented independently and will be provided to the TextEditor at the time of TextEditor instantiation. This entire procedure is controlled by the Spring Framework.
Here, we have removed total control from the TextEditor and kept it somewhere else (i.e. XML configuration file) and the dependency (i.e. class SpellChecker) is being injected into the class TextEditor through a Class Constructor. Thus the flow of control has been "inverted" by Dependency Injection (DI) because you have effectively delegated dependances to some external system.
The second method of injecting dependency is through Setter Methods of the TextEditor class where we will create a SpellChecker instance. This instance will be used to call setter methods to initialize TextEditor's properties.
Thus, DI exists in two major variants and the following two sub-chapters will cover both of them with examples &
Dependency Injection Type & Description
Constructor-based DI is accomplished when the container invokes a class constructor with a number of arguments, each representing a dependency on the other class.
Setter-based DI is accomplished by the container calling setter methods on your beans after invoking a no-argument constructor or no-argument static factory method to instantiate your bean.
You can mix both, Constructor-based and Setter-based DI but it is a good rule of thumb to use constructor arguments for mandatory dependencies and setters for optional dependencies.
The code is cleaner with the DI principle and decoupling is more effective when objects are provided with their dependencies. The object does not look up its dependencies and does not know the location or class of the dependencies, rather everything is taken care by the Spring Framework.
Spring - Injecting Inner Beans
As you know Java inner classes are defined within the scope of other classes, similarly, inner beans are beans that are defined within the scope of another bean. Thus, a &bean/& element inside the &property/& or &constructor-arg/& elements is called inner bean and it is shown below.
&?xml version = "1.0" encoding = "UTF-8"?&
&beans xmlns = "http://www.springframework.org/schema/beans"
xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation = "http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd"&
&bean id = "outerBean" class = "..."&
&property name = "target"&
&bean id = "innerBean" class = "..."/&
&/property&
Let us have working Eclipse IDE in place and follow the following steps to create a Spring application &
Description
Create a project with a name SpringExample and create a package com.tutorialspoint under the src folder in the created project.
Add required Spring libraries using Add External JARs option as explained in the Spring Hello World Example chapter.
Create Java classes TextEditor, SpellChecker and MainApp under the com.tutorialspoint package.
Create Beans configuration file Beans.xml under the src folder.
The final step is to create the content of all the Java files and Bean Configuration file and run the application as explained below.
Here is the content of TextEditor.java file &
package com.
public class TextEditor {
private SpellChecker spellC
// a setter method to inject the dependency.
public void setSpellChecker(SpellChecker spellChecker) {
System.out.println("Inside setSpellChecker." );
this.spellChecker = spellC
// a getter method to return spellChecker
public SpellChecker getSpellChecker() {
return spellC
public void spellCheck() {
spellChecker.checkSpelling();
Following is the content of another dependent class file SpellChecker.java &
package com.
public class SpellChecker {
public SpellChecker(){
System.out.println("Inside SpellChecker constructor." );
public void checkSpelling(){
System.out.println("Inside checkSpelling." );
Following is the content of the MainApp.java file &
package com.
import org.springframework.context.ApplicationC
import org.springframework.context.support.ClassPathXmlApplicationC
public class MainApp {
public static void main(String[] args) {
ApplicationContext context = new ClassPathXmlApplicationContext("Beans.xml");
TextEditor te = (TextEditor) context.getBean("textEditor");
te.spellCheck();
Following is the configuration file Beans.xml which has configuration for the setter-based injection but using inner beans &
&?xml version = "1.0" encoding = "UTF-8"?&
&beans xmlns = "http://www.springframework.org/schema/beans"
xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation = "http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd"&
&!-- Definition for textEditor bean using inner bean --&
&bean id = "textEditor" class = "com.tutorialspoint.TextEditor"&
&property name = "spellChecker"&
&bean id = "spellChecker" class = "com.tutorialspoint.SpellChecker"/&
&/property&
Once you are done creating the source and bean configuration files, let us run the application. If everything is fine with your application, it will print the following message &
Inside SpellChecker constructor.
Inside setSpellChecker.
Inside checkSpelling.
Spring - Injecting Collection
You have seen how to configure primitive data type using value attribute and object references using ref attribute of the &property& tag in your Bean configuration file. Both the cases deal with passing singular value to a bean.
Now what if you want to pass plural values like Java Collection types such as List, Set, Map, and Properties. To handle the situation, Spring offers four types of collection configuration elements which are as follows &
Element & Description
This helps in wiring ie injecting a list of values, allowing duplicates.
This helps in wiring a set of values but without any duplicates.
This can be used to inject a collection of name-value pairs where name and value can be of any type.
This can be used to inject a collection of name-value pairs where the name and value are both Strings.
You can use either &list& or &set& to wire any implementation of java.util.Collection or an array.
You will come across two situations (a) Passing direct values of the collection and (b) Passing a reference of a bean as one of the collection elements.
Let us have a working Eclipse IDE in place and take the following steps to create a Spring application &
Description
Create a project with a name SpringExample and create a package com.tutorialspoint under the src folder in the created project.
Add required Spring libraries using Add External JARs option as explained in the Spring Hello World Example chapter.
Create Java classes JavaCollection, and MainApp under the com.tutorialspoint package.
Create Beans configuration file Beans.xml under the src folder.
The final step is to create the content of all the Java files and Bean Configuration file and run the application as explained below.
Here is the content of JavaCollection.java file &
package com.
import java.util.*;
public class JavaCollection {
List addressL
Properties addressP
// a setter method to set List
public void setAddressList(List addressList) {
this.addressList = addressL
// prints and returns all the elements of the list.
public List getAddressList() {
System.out.println("List Elements :"
+ addressList);
return addressL
// a setter method to set Set
public void setAddressSet(Set addressSet) {
this.addressSet = addressS
// prints and returns all the elements of the Set.
public Set getAddressSet() {
System.out.println("Set Elements :"
+ addressSet);
return addressS
// a setter method to set Map
public void setAddressMap(Map addressMap) {
this.addressMap = addressM
// prints and returns all the elements of the Map.
public Map getAddressMap() {
System.out.println("Map Elements :"
+ addressMap);
return addressM
// a setter method to set Property
public void setAddressProp(Properties addressProp) {
this.addressProp = addressP
// prints and returns all the elements of the Property.
public Properties getAddressProp() {
System.out.println("Property Elements :"
+ addressProp);
return addressP
Following is the content of the MainApp.java file &
package com.
import org.springframework.context.ApplicationC
import org.springframework.context.support.ClassPathXmlApplicationC
public class MainApp {
public static void main(String[] args) {
ApplicationContext context = new ClassPathXmlApplicationContext("Beans.xml");
JavaCollection jc=(JavaCollection)context.getBean("javaCollection");
jc.getAddressList();
jc.getAddressSet();
jc.getAddressMap();
jc.getAddressProp();
Following is the configuration file Beans.xml which has configuration for all the type of collections &
&?xml version = "1.0" encoding = "UTF-8"?&
&beans xmlns = "http://www.springframework.org/schema/beans"
xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation = "http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd"&
&!-- Definition for javaCollection --&
&bean id = "javaCollection" class = "com.tutorialspoint.JavaCollection"&
&!-- results in a setAddressList(java.util.List) call --&
&property name = "addressList"&
&value&INDIA&/value&
&value&Pakistan&/value&
&value&USA&/value&
&value&USA&/value&
&/property&
&!-- results in a setAddressSet(java.util.Set) call --&
&property name = "addressSet"&
&value&INDIA&/value&
&value&Pakistan&/value&
&value&USA&/value&
&value&USA&/value&
&/property&
&!-- results in a setAddressMap(java.util.Map) call --&
&property name = "addressMap"&
&entry key = "1" value = "INDIA"/&
&entry key = "2" value = "Pakistan"/&
&entry key = "3" value = "USA"/&
&entry key = "4" value = "USA"/&
&/property&
&!-- results in a setAddressProp(java.util.Properties) call --&
&property name = "addressProp"&
&prop key = "one"&INDIA&/prop&
&prop key = "one"&INDIA&/prop&
&prop key = "two"&Pakistan&/prop&
&prop key = "three"&USA&/prop&
&prop key = "four"&USA&/prop&
&/property&
Once you are done creating the source and bean configuration files, let us run the application. If everything is fine with your application, it will print the following message &
List Elements :[INDIA, Pakistan, USA, USA]
Set Elements :[INDIA, Pakistan, USA]
ap Elements :{1 = INDIA, 2 = Pakistan, 3 = USA, 4 = USA}
Property Elements :{two = Pakistan, one = INDIA, three = USA, four = USA}
Injecting Bean References
The following Bean definition will help you understand how to inject bean references as one of the collection's element. Even you can mix references and values all together as shown in the following code snippet &
&?xml version = "1.0" encoding = "UTF-8"?&
&beans xmlns = "http://www.springframework.org/schema/beans"
xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation = "http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd"&
&!-- Bean Definition to handle references and values --&
&bean id = "..." class = "..."&
&!-- Passing bean reference
for java.util.List --&
&property name = "addressList"&
&ref bean = "address1"/&
&ref bean = "address2"/&
&value&Pakistan&/value&
&/property&
&!-- Passing bean reference
for java.util.Set --&
&property name = "addressSet"&
&ref bean = "address1"/&
&ref bean = "address2"/&
&value&Pakistan&/value&
&/property&
&!-- Passing bean reference
for java.util.Map --&
&property name = "addressMap"&
&entry key = "one" value = "INDIA"/&
&entry key = "two" value-ref = "address1"/&
&entry key = "three" value-ref = "address2"/&
&/property&
To use the above bean definition, you need to define your setter methods in such a way that they should be able to handle references as well.
Injecting null and empty string values
If you need to pass an empty string as a value, then you can pass it as follows &
&bean id = "..." class = "exampleBean"&
&property name = "email" value = ""/&
The preceding example is equivalent to the Java code: exampleBean.setEmail("")
If you need to pass a NULL value, then you can pass it as follows &
&bean id = "..." class = "exampleBean"&
&property name = "email"&&null/&&/property&
The preceding example is equivalent to the Java code: exampleBean.setEmail(null)
Spring - Beans Auto-Wiring
You have learnt how to declare beans using the &bean& element and inject &bean& using &constructor-arg& and &property& elements in XML configuration file.
The Spring container can autowirerelationships between collaborating beans without using &constructor-arg& and &property& elements, which helps cut down on the amount of XML configuration you write for a big Spring-based application.
Autowiring Modes
Following are the autowiring modes, which can be used to instruct the Spring container to use autowiring for dependency injection. You use the autowire attribute of the &bean/& element to specify autowire mode for a bean definition.
Mode & Description
This is default setting which means no autowiring and you should use explicit bean reference for wiring. You have nothing to do special for this wiring. This is what you already have seen in Dependency Injection chapter.
Autowiring by property name. Spring container looks at the properties of the beans on which autowire attribute is set to byName in the XML configuration file. It then tries to match
and wire its properties with the beans defined by the same names in the configuration file.
Autowiring by property datatype. Spring container looks at the properties of the beans on which autowire attribute is set to byType in the XML configuration file. It then tries to match
and wire a property if its type matches with exactly one of the beans name in configuration file. If more than one such beans exists, a fatal exception is thrown.
Similar to byType, but type applies to constructor arguments. If there is not exactly one bean of the constructor argument type in the container, a fatal error is raised.
autodetect
Spring first tries to wire using autowire by constructor, if it does not work, Spring tries to autowire by byType.
You can use byType or constructor autowiring mode to wire arrays and other typed-collections.
Limitations with autowiring
Autowiring works best when it is used consistently across a project. If autowiring is not used in general, it might be confusing for developers to use it to wire only one or two bean definitions. Though, autowiring can significantly reduce the need to specify properties or constructor arguments but you should consider the limitations and disadvantages of autowiring before using them.
Limitations & Description
Overriding possibility
You can still specify dependencies using &constructor-arg& and &property& settings which will always override autowiring.
Primitive data types
You cannot autowire so-called simple properties such as primitives, Strings, and Classes.
Confusing nature
Autowiring is less exact than explicit wiring, so if possible prefer using explict wiring.
Spring - Annotation Based Configuration
Starting from Spring 2.5 it became possible to configure the dependency injection using annotations. So instead of using XML to describe a bean wiring, you can move the bean configuration into the component class itself by using annotations on the relevant class, method, or field declaration.
Annotation injection is performed before XML injection. Thus, the latter configuration will override the former for properties wired through both approaches.
Annotation wiring is not turned on in the Spring container by default. So, before we can use annotation-based wiring, we will need to enable it in our Spring configuration file. So consider the following configuration file in case you want to use any annotation in your Spring application.
&?xml version = "1.0" encoding = "UTF-8"?&
&beans xmlns = "http://www.springframework.org/schema/beans"
xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance"
xmlns:context = "http://www.springframework.org/schema/context"
xsi:}