spring的beans.xml的配置

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <beans xmlns="http://www.springframework.org/schema/beans"
 3        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 4        xsi:schemaLocation="http://www.springframework.org/schema/beans
 5            http://www.springframework.org/schema/beans/spring-beans-2.5.xsd">
 6            
 7   <!--接口注入,UserDAOImpl是实现UserDAO的接口类，主要就是实现数据库的操作，根据不同的数据库类型实现不同的类操作。-->
 8   <bean id="u" class="com.bjsxt.dao.impl.UserDAOImpl"> 
 9   </bean>
10     
11   <bean id="userService" class="com.bjsxt.service.UserService">
12       <!--1、set方法注入，主要用这种方法。-->
13       <property name="userDAO" ref="u" /> 
14     <!--2、构造方法注入-->
15     <!--
16        <constructor-arg> 
17            <ref bean="u"/>
18        </constructor-arg>
19      -->
20   </bean>
21 </beans>

UserDAO.java如下：

1 package com.bjsxt.dao;
2 import com.bjsxt.model.User;
3 
4 
5 public interface UserDAO {
6     public void save(User user);
7 }

UserDAOImpl.java如下：

 1 package com.bjsxt.dao.impl;
 2 import com.bjsxt.dao.UserDAO;
 3 import com.bjsxt.model.User;
 4 
 5 public class UserDAOImpl implements UserDAO {
 6     public void save(User user) {
 7         //Hibernate
 8         //JDBC
 9         //XML
10         //NetWork
11         System.out.println("user saved!");
12     }
13 }

User.java如下：

package com.bjsxt.model;

public class User {
    private String username;
    private String password;
    public String getUsername() {
        return username;
    }
    public void setUsername(String username) {
        this.username = username;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }
}

UserService.java如下：

 1 package com.bjsxt.service;
 2 import com.bjsxt.dao.UserDAO;
 3 import com.bjsxt.model.User;
 4 
 5 public class UserService {
 6     private UserDAO userDAO;  
 7     /*用于beans.xml中构造方法的注入使用的；
 8     public UserService(UserDAO userDAO){
 9         this.userDAO=userDAO;
10     }
11     */
12     public void add(User user) {
13         userDAO.save(user);
14     }
15     public UserDAO getUserDAO() {
16         return userDAO;
17     }
18     public void setUserDAO(UserDAO userDAO) {
19         this.userDAO = userDAO;
20     }
21 }

那么如何来使用呢？如下代码是写在测试单元中的：
UserServiceTest.java：

 1 package com.bjsxt.service;
 2 import org.junit.Test;
 3 import org.springframework.context.ApplicationContext;
 4 import org.springframework.context.support.ClassPathXmlApplicationContext;
 5 import com.bjsxt.model.User;
 6 
 7 //Dependency Injection
 8 //Inverse of Control
 9 public class UserServiceTest {
10 
11     @Test
12     public void testAdd() throws Exception {
13         /*读取beans.xml文件ClassPathXmlApplicationContext会把读取的内容放入到bean容器中；*/
14         ApplicationContext ctx = new ClassPathXmlApplicationContext("beans.xml");
15         /*读取注入*/
16         UserService service = (UserService)ctx.getBean("userService");    
17         User u = new User();
18         u.setUsername("zhangsan");
19         u.setPassword("zhangsan");
20         service.add(u);
21     }
22 }