以下是用Annotation的配置方式来实现简单Spring IOC

 

<!--第一步 配置aplicationContext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.xsd
         http://www.springframework.org/schema/context
         http://www.springframework.org/schema/context/spring-context.xsd">

   <context:annotation-config/>
   <context:component-scan base-package="com.tz.spring.entity"/>

</beans>

package com.tz.spring.entity;

import org.springframework.stereotype.Component;

@Component//此标注声明将Cat放入容器中默认的id就是类名首字母小写，可以显示声明（value=” ”)
public class Cat {
    
    private int id=200;
    private String name="黑猫";
    
    public Cat(){
        id=100;
        name="白猫";
    }
    @Override
    public String toString() {
        return id+name;
    }

}

package com.tz.spring.entity;

import javax.annotation.Resource;

import org.springframework.stereotype.Component;

@Component
public class User {
    
    private int id;
    private String name;
    @Resource//此标签声明对cat的引用，在默认情况下，会先匹配依赖的id
             //然后找属于Cat类型的依赖，如果没找到则什么都不做
             //如果找到一个则直接赋值，如果找到多个则报错
    private Cat cat;
    
    public User(){
        
        id=110;
        name="小张";
        
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Cat getCat() {
        return cat;
    }

    public void setCat(Cat cat) {
        this.cat = cat;
    }
    
    @Override
    public String toString() {
        
        return id+name+cat;
    }
    
    

}

第三步测试：从容器中拿出User的一个实例；

public void testcat(){
        
      ApplicationContext ac = new ClassPathXmlApplicationContext("applicationContext.xml");
      User user = (User)ac.getBean("user");
      
      System.out.println(user);
        
    }