简单的IOC控制反转实现

1。编写接口

package com.yyf.dao;

public interface UserDao {
    void getUser();
}

2.编写多个实现类

package com.yyf.dao;

public class UserDaoImpl implements UserDao{
    @Override
    public void getUser() {
        System.out.println ("UserDao获取数据");
    }
}

package com.yyf.dao;

public class UserDaoMysqlImpl implements UserDao{
    @Override
    public void getUser() {
        System.out.println ("Mysql获取数据");
    }
}

package com.yyf.dao;

public class UserDaoOracleImpl implements UserDao{
    @Override
    public void getUser() {
        System.out.println ("oracle获取数据");
    }
}

3.利用set方法进行动态实现值的注入，这是ioc的重点体现

package com.yyf.service;

import com.yyf.dao.UserDao;
import com.yyf.dao.UserDaoImpl;

public class UserServiceImpl implements UserService{
    private UserDao userDao;

    //利用 set进行动态实现值的注入      IOC的重点体现
    public void setUserDao(UserDao userDao) {
        this.userDao = userDao;
    }

    @Override
    public void getUser() {
         userDao.getUser ();
    }
}

4.在spring配置文件中，对UserServiceImpl实现类的userdao变量进行引用

5.测试   通过改变配置文件的ref 的引用，来实现不同的注入

import com.yyf.dao.UserDaoMysqlImpl;
import com.yyf.service.UserService;
import com.yyf.service.UserServiceImpl;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class MyTest {
    public static void main(String[] args) {

                ApplicationContext context = new ClassPathXmlApplicationContext ("beans.xml");
             UserServiceImpl serviceImpl = (UserServiceImpl) context.getBean ("serviceImpl");
                      serviceImpl.getUser ();
    }
}