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11-Spring配置文件-依赖注入1(bean的嵌套调用)

发布时间：2024-12-18 20:24:54编辑：雪饮阅读（）

使用bean获取implement的实例还可以支持嵌套的形式，例如我有UserDaoImpl实现UserDao
package com.dao.impl;

import com.dao.UserDao;

public class UserDaoImpl implements UserDao {
    public UserDaoImpl(){
        System.out.println("-----UserDaoImpl被创建--------");
    }
    public void save() {
        System.out.println("-----UserDaoImpl save--------");
    }
    public void init(){
        System.out.println("执行了init方法");
    }
    public void destroy(){
        System.out.println("执行了destroy方法");
    }
}
 
然后我用UserServiceImpl实现UserService然后去调用UserDao的save方法
package com.service.impl;

import com.dao.UserDao;
import com.service.UserService;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class UserServiceImplement implements UserService {
    public void save() {
        ApplicationContext app=new ClassPathXmlApplicationContext("applicationContext.xml");
        UserDao userDao= (UserDao) app.getBean("userDao");
        userDao.save();
    }
}
然后最后假定我们的入口类去调用UserService的save方法
package com.web;
import com.service.UserService;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Index {
    public static void main(String[] args) {
        ApplicationContext app=new ClassPathXmlApplicationContext("applicationContext.xml");
        UserService userService= (UserService) app.getBean("userService");
        userService.save();
    }
}
那么我们的Spring Config配置文件则如：
<?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.xsd">

        <bean id="userDao" class="com.dao.impl.UserDaoImpl"></bean>
        <bean id="userService" class="com.service.impl.UserServiceImplement"></bean>
</beans>