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  • 学习spring笔记

    依赖

    <dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-webmvc</artifactId>
    <version>5.3.9</version>
    </dependency>

    AOP

    IOC理论推导 控制反转,主动权交给用户

    1.dao层是用来实现业务,和数据库打交道

    dao层 接口

    package com.tengxian.dao;
    
    public interface UserDao {
        void getUser();
    }

    dao接口的实现1,默认获取

    package com.tengxian.dao;
    
    public class UserDaoImpl implements UserDao{
        @Override
        public void getUser() {
            System.out.println("默认获取用户是数据");
        }
    }

    dao接口的实现类2,mysql获取

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

    service层,

    服务层接口

    package com.tengxian.service;
    
    public interface  UserService {
        void getUser();
    }

    服务处实现类

    package com.tengxian.service;
    
    import com.tengxian.dao.UserDao;
    import com.tengxian.dao.UserDaoImpl;
    
    public class UserServiceImpl implements UserService{
    
        //业务层调用Dao层
        private UserDao userDao;
    
        //利用set进行动态实现值的注入
        public void setUserDao(UserDao userDao) {
            this.userDao = userDao;
        }
    
        @Override
        public void getUser() {
            userDao.getUser();
        }
    }

    用户层:用户实际要用的是业务层,dao层他们不用接触

    import com.tengxian.dao.UserDaoImpl;
    import com.tengxian.dao.UserDaoMysqlImpl;
    import com.tengxian.service.UserServiceImpl;
    
    public class MyTest {
        public static void main(String[] args) {
            //用户实际要用的是业务层,dao层他们不用接触
            UserServiceImpl userService = new UserServiceImpl();
            userService.setUserDao(new UserDaoImpl());
    
            userService.getUser();
        }
    }
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  • 原文地址:https://www.cnblogs.com/trevain/p/15088276.html
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