Spring——IOC（四）

九、Annotation——AutoWired和Qualifier

配置文件如下：

<?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:schemaLocation="http://www.springframework.org/schema/beans

           http://www.springframework.org/schema/beans/spring-beans-2.5.xsd

           http://www.springframework.org/schema/context

http://www.springframework.org/schema/context/spring-context-2.5.xsd">

<context:annotation-config></context:annotation-config>

  <bean id="u" class="com.zgy.impl.UserDAOImpl">

  </bean>

  <bean id="userService" class="com.zgy.service.UserService" >

  </bean>

</beans>

 

 

以下的这段配置配上了以后，其实就已经实例化了如下的4个bean，<context:annotation-config></context:annotation-config>

AutowiredAnnotationBeanPostProcessor, CommonAnnotationBeanPostProcessor,PersistenceAnnotationBeanPostProcessor,  RequiredAnnotationBeanPostProcessor

使用以上的配置之后，还需要在对应的setter方法上加入对应的Annotation

package com.zgy.service;

 

import org.springframework.beans.factory.annotation.Autowired;

 

import com.zgy.dao.UserDAO;

import com.zgy.model.User;

 

public class UserService {

private UserDAO userDAO;

public void init(){

System.out.println("init");

}

public void add(User u){

this.userDAO.save(u);

}

 

public UserDAO getUserDAO() {

return userDAO;

}

@Autowired

public void setUserDAO(UserDAO userDAO) {

this.userDAO = userDAO;

}

public void destory(){

System.out.println("destroy");

}

}

运行测试程序后，观察结果：

user saved

以上的Annotation配置与XML中的 autowire="byType"的配置作用相同。

如果想实现相当于XML中 autowire="byName"的效果，可以使用如下方法：

增加@Qualifier("u2")注解

实验：

（1）修改UserService

package com.zgy.service;

 

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.beans.factory.annotation.Qualifier;

 

import com.zgy.dao.UserDAO;

import com.zgy.model.User;

 

public class UserService {

private UserDAO userDAO;

public void init(){

System.out.println("init");

}

public void add(User u){

this.userDAO.save(u);

}

 

public UserDAO getUserDAO() {

return userDAO;

}

@Autowired

public void setUserDAO(@Qualifier("u2")UserDAO userDAO) {

this.userDAO = userDAO;

}

public void destory(){

System.out.println("destroy");

}

}

 

（2）在配置文件中增加一个bean

<?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:schemaLocation="http://www.springframework.org/schema/beans        http://www.springframework.org/schema/beans/spring-beans-2.5.xsd         http://www.springframework.org/schema/context          http://www.springframework.org/schema/context/spring-context-2.5.xsd">

<context:annotation-config></context:annotation-config>

  <bean id="u" class="com.zgy.impl.UserDAOImpl">

  </bean>

  <bean id="u2" class="com.zgy.impl.UserDAOImpl">

  </bean>

  <bean id="userService" class="com.zgy.service.UserService">

  </bean>

</beans>

（3）测试，观察结果：

user saved

十、Annotation——Resource

使用@Resource这个注解也可以实现注入。实现如下：

（1）在方法上加上@Resource

package com.zgy.service;

import javax.annotation.Resource;

import org.springframework.beans.factory.annotation.Qualifier;

import com.zgy.dao.UserDAO;

import com.zgy.model.User;

public class UserService {

private UserDAO userDAO;

public void init(){

System.out.println("init");

}

public void add(User u){

this.userDAO.save(u);

}

public UserDAO getUserDAO() {

return userDAO;

}

@Resource

public void setUserDAO(UserDAO userDAO) {

this.userDAO = userDAO;

}

public void destory(){

System.out.println("destroy");

}

}

（2）在配置文件中配置一个bean

<?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:schemaLocation="http://www.springframework.org/schema/beans

           http://www.springframework.org/schema/beans/spring-beans-2.5.xsd

           http://www.springframework.org/schema/context

           http://www.springframework.org/schema/context/spring-context-2.5.xsd">

<context:annotation-config></context:annotation-config>

  <bean id="u" class="com.zgy.impl.UserDAOImpl">

  </bean>

  <bean id="userService" class="com.zgy.service.UserService">

  </bean>

  </beans>

（3）测试

package com.bjsxt.service;

import org.junit.Test;

import org.springframework.context.ApplicationContext;

import org.springframework.context.support.ClassPathXmlApplicationContext;

import com.zgy.dao.UserDAO;

import com.zgy.model.User;

import com.zgy.service.UserService;

 

 

public class UserServiceTest {

 

@Test

public void testAdd() throws Exception {

ClassPathXmlApplicationContext applicationContext = new ClassPathXmlApplicationContext("beans.xml");

UserService userService= (UserService) applicationContext.getBean("userService");

userService.add(new User());

}

 

}

（4）结论：@Resource默认是按照类型来注入的。当存在两个相同类型的bean的时候，@Resource需要加上额外的name属性指明使用的是哪一个bean

（5）范例：

<?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:schemaLocation="http://www.springframework.org/schema/beans

           http://www.springframework.org/schema/beans/spring-beans-2.5.xsd

           http://www.springframework.org/schema/context

           http://www.springframework.org/schema/context/spring-context-2.5.xsd">

<context:annotation-config></context:annotation-config>

  <bean id="u" class="com.zgy.impl.UserDAOImpl">

  </bean>

  <bean id="u2" class="com.zgy.impl.UserDAOImpl">

  </bean>

  <bean id="userService" class="com.zgy.service.UserService">

  </bean>

  </beans>

（６）此时需要在@Resource(name="u")用来指定是用的是名字为u的这个bean

package com.zgy.service;

 

import javax.annotation.Resource;

import org.springframework.beans.factory.annotation.Qualifier;

 

import com.zgy.dao.UserDAO;

import com.zgy.model.User;

 

public class UserService {

private UserDAO userDAO;

public void init(){

System.out.println("init");

}

public void add(User u){

this.userDAO.save(u);

}

 

public UserDAO getUserDAO() {

return userDAO;

}

@Resource(name="u")

public void setUserDAO(UserDAO userDAO) {

this.userDAO = userDAO;

}

public void destory(){

System.out.println("destroy");

}

}

 

 

 

十一、Annotation——Component

在配置文件中可以不明确的写出需要注入的bean，而是通过<context:component-scan base-package="包路径" />的形式让Spring自动所有包下的符合注入条件的bean

实验：

（1）修改配置文件

<?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:schemaLocation="http://www.springframework.org/schema/beans

           http://www.springframework.org/schema/beans/spring-beans-2.5.xsd

           http://www.springframework.org/schema/context

           http://www.springframework.org/schema/context/spring-context-2.5.xsd">

<context:annotation-config></context:annotation-config>

<context:component-scan base-package="com.zgy" />

  <bean id="userService" class="com.zgy.service.UserService">

  </bean>

</beans>

（2）在UserDAOImpl中添加@Component注解

package com.zgy.impl;

import org.springframework.stereotype.Component;

import com.zgy.dao.UserDAO;

import com.zgy.model.User;

@Component

public class UserDAOImpl implements UserDAO{

@Override

public void save(User u) {

System.out.println("user saved");

}

}

 

（3）在UserService中添加@Resource

package com.zgy.service;

import javax.annotation.Resource;

import org.springframework.beans.factory.annotation.Qualifier;

 

import com.zgy.dao.UserDAO;

import com.zgy.model.User;

 

public class UserService {

private UserDAO userDAO;

public void init(){

System.out.println("init");

}

public void add(User u){

this.userDAO.save(u);

}

public UserDAO getUserDAO() {

return userDAO;

}

@Resource

public void setUserDAO(UserDAO userDAO) {

this.userDAO = userDAO;

}

public void destory(){

System.out.println("destroy");

}

}

 

（4）测试：

package com.bjsxt.service;

import org.junit.Test;

import org.springframework.context.ApplicationContext;

import org.springframework.context.support.ClassPathXmlApplicationContext;

import com.zgy.dao.UserDAO;

import com.zgy.model.User;

import com.zgy.service.UserService;

public class UserServiceTest {

@Test

public void testAdd() throws Exception {

ClassPathXmlApplicationContext applicationContext = new ClassPathXmlApplicationContext("beans.xml");

UserService userService= (UserService) applicationContext.getBean("userService");

userService.add(new User());

}

}

 

（5）结论：

userService这个bean中的属性UserDAO属性，由于配置文件中没有配置该属性，所以会根据<context:component-scan base-package="com.zgy" />在com.zgy的包名下进行搜索，当找到@Component时，即找到了适合的信息

（6）也可以通过@Component(value="u")和Resource(name="u")的形式指定名称。

 

 

 

十二、Annotation——@Scope，@PostConstruct，@PreDestroy

@Scope作用是限制bean的生存范围，常用的取值有singleton、prototype

 

@PostConstruct定义初始化方法

@PreDestory定义销毁方法

范例：

（1）UserService.java

package com.zgy.service;

 

import javax.annotation.PostConstruct;

import javax.annotation.PreDestroy;

import javax.annotation.Resource;

import org.springframework.beans.factory.annotation.Qualifier;

import org.springframework.context.annotation.Scope;

import org.springframework.stereotype.Component;

 

import com.zgy.dao.UserDAO;

import com.zgy.model.User;

@Component

@Scope("prototype")

public class UserService {

private UserDAO userDAO;

@PostConstruct

public void init(){

System.out.println("init");

}

public void add(User u){

this.userDAO.save(u);

}

 

public UserDAO getUserDAO() {

return userDAO;

}

@Resource(name="u")

public void setUserDAO(UserDAO userDAO) {

this.userDAO = userDAO;

}

@PreDestroy

public void destory(){

System.out.println("destroy");

}

}

 

（2）UserDAOImpl.java

package com.zgy.impl;

 

import org.springframework.context.annotation.Scope;

import org.springframework.stereotype.Component;

 

import com.zgy.dao.UserDAO;

import com.zgy.model.User;

@Component(value="u")

@Scope("prototype")

public class UserDAOImpl implements UserDAO{

 

 

@Override

public void save(User u) {

System.out.println("user saved");

}

}

 

（3）测试：

package com.bjsxt.service;

import org.junit.Test;

import org.springframework.context.ApplicationContext;

import org.springframework.context.support.ClassPathXmlApplicationContext;

import com.zgy.dao.UserDAO;

import com.zgy.model.User;

import com.zgy.service.UserService;

 

 

public class UserServiceTest {

 

@Test

public void testAdd() throws Exception {

ClassPathXmlApplicationContext applicationContext = new ClassPathXmlApplicationContext("beans.xml");

UserService userService= (UserService) applicationContext.getBean("userService");

UserService userService2= (UserService) applicationContext.getBean("userService");

System.out.println(userService == userService2);

userService.add(new User());

applicationContext.destroy();

}

}