Spring依赖注入/控制反转原理实例

骑猪看日落 2022-07-12 04:20 314阅读 0赞

代码：

1.配置文件

applicationContext.xml

<?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:p="http://www.springframework.org/schema/p"
    	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd">
    	
    	
    	<bean id="userDAO" class="com.springtest1.dao.UserDAOImpl">	 
    	</bean>
    	
    	<bean id="userBiz" class="com.springtest1.biz.UserBizImpl">
    	  
    	  <property name="userDAO" ref="userDAO" />
    	</bean>	
    	
    </beans>

源代码：

UserDAO.java

package com.springtest1.dao;
    
    public interface UserDAO {
       public boolean login(String username,String password);
    }

UserDAOImpl.java

package com.springtest1.dao;
    
    public class UserDAOImpl implements UserDAO {
    
    	@Override
    	public boolean login(String username, String password) {
    		// TODO Auto-generated method stub
    		if(username.equals("admin") && password.equals("123")){
    			return true;
    		}
    		return false;
    	}
    
    }

UserBiz.java

package com.springtest1.biz;
    
    public interface UserBiz {
       public boolean login(String username,String password);
    }

UserBizImpl.java

package com.springtest1.biz;
    
    import com.springtest1.dao.UserDAO;
    import com.springtest1.dao.UserDAOImpl;
    public class UserBizImpl implements UserBiz {
    
    	//使用UserDAO接口声明了一个对象
    	//并为其添加set方法，用于依赖注入
    	UserDAO userDAO;
    	public void setUserDAO(UserDAO userDAO){
    		this.userDAO=userDAO;
    	}
    	public boolean login(String username, String password) {
    		// TODO Auto-generated method stub
    		return userDAO.login(username, password);
    	}
    
    }

3.测试函数

TestSpring.java

package com.springtest1;
    
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.support.ClassPathXmlApplicationContext;
    
    import com.springtest1.biz.UserBiz;
    
    public class TestSpring {
    
    	public static void main(String[] args) {
    	   //加载applicationContext.xml配置
    		ApplicationContext context=new ClassPathXmlApplicationContext("applicationContext.xml");
    		//获取配置中的UserBizImpl 实例
    		UserBiz userBiz=(UserBiz) context.getBean("userBiz");//调用方法
    		boolean flag=userBiz.login("admin", "123");
    		if(flag){
    			System.out.println("登录成功");
    		}else{
    			System.out.println("登录失败");
    		}
    	}
    
    }

4.截图

![Center][]

[Center]: /images/20220711/6c83420d61fe4fa3a2ce9dfc72f68779.png