Spring Boot 增删改查（mybatis-plus）

在GitHub上已经开源，有全部源码，有问题可以在GitHub上提问https://github.com/sky41/MySQL.git
1、创建(User) 实体类

package com.my.mysql.entity;  import lombok.*;  @Setter  
@Getter  
@Data  
@NoArgsConstructor  
//@AllArgsConstructor  
public class User {  private int id;  private String name;  private String passwd;  public User(int id, String name, String passwd) {  this.id = id;  this.name = name;  this.passwd = passwd;  }  public void updateUser(String name, String passwd) {  if (name != null) {  this.name = name;  }  if (passwd != null) {  this.passwd = passwd;  }  }  public static void main(String[] args) {  User user = new User(123, "Alice", "30");  System.out.println("Before update:");  System.out.println("Name: " + user.getName());  System.out.println("Passwd: " + user.getPasswd());  user.updateUser(null, "newPassword");  System.out.println("\nAfter update:");  System.out.println("Name: " + user.getName());  System.out.println("Passwd: " + user.getPasswd());  }  
}

2、创建(User) Mapper接口

package com.my.mysql.mapper;  import com.my.mysql.entity.User;  
import org.apache.ibatis.annotations.Mapper;  
import org.springframework.stereotype.Repository;  import java.util.List;  @Mapper  
@Repository  
public interface UserMapper {  List<User> queryUserList();  User queryUserById(int id);  void addUser(User user);  void deleteUserById(int id);  void updateUser(User user);  
//    void login(User user);  
//    void register(User user);  }

3、配置(User)Mapper.xml

<?xml version="1.0" encoding="UTF-8" ?>  
<!DOCTYPE mapper  PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"  "http://mybatis.org/dtd/mybatis-3-mapper.dtd">  <mapper namespace="com.my.mysql.mapper.UserMapper">  <select id="queryUserList" resultType="User">  select * from mysqluser.user  </select>  <select id="queryUserById" resultType="User" parameterType="int">  select * from mysqluser.user where id = #{id};  </select>  <insert id="addUser">  insert into mysqluser.user (id, name,passwd) VALUES (#{id},#{name},#{passwd})  </insert>  <delete id="deleteUserById">  delete from mysqluser.user where id=#{id}  </delete>  <update id="updateUser" parameterType="User">  UPDATE mysqluser.user  
#         UPDATE mysqluser.user user是使用的数据库里面数据表  SET  id = #{id},        name = #{name},        passwd = #{passwd}        WHERE id = #{id}    </update>  </mapper>

4、创建(User) service类
service接口可以分出来实现类单独编写

package com.my.mysql.service;  import com.my.mysql.entity.User;  import java.util.List;  public interface UserService {  List<User> queryUserList();  User queryUserById(int id);  String addUser(User user);  String deleteUserById(int id);  String updateUser(User user);  }

4.1创建（User）实现类

package com.my.mysql.service.Impl;  import com.my.mysql.controller.UserController;  
import com.my.mysql.entity.User;  
import com.my.mysql.mapper.UserMapper;  
import com.my.mysql.service.UserService;  
import org.springframework.beans.factory.annotation.Autowired;  
import org.springframework.stereotype.Service;  import java.util.List;  @Service  
public class UserServiceImpl implements UserService {  @Autowired  private UserMapper userMapper;  @Autowired  private UserController userController;  @Override  public List<User> queryUserList() {  return userMapper.queryUserList();  }  @Override  public User queryUserById(int id) {  return userMapper.queryUserById(id);  }  @Override  public String addUser(User user) {  userMapper.addUser(user);  return "新增成功";  }  @Override  public String deleteUserById(int id) {  userMapper.deleteUserById(id);  return "删除成功";  }  @Override  public String updateUser(User user) {  if (user != null) {  userMapper.updateUser(user);  return "更新成功";  } else {  return "用户信息为空，更新失败";  }  }  
//    @Override  
//    public User login(String name, String passwd) {  
//        // 根据用户名在数据库中查询用户信息  
//        userMapper.login();  
//  
//        if (user != null && user.getPasswd().equals(passwd)) {  
//            return user; // 返回用户信息表示登录成功  
//        } else {  
//            return null; // 返回null表示登录失败  
//        }  
//    }  
//    public String register(User newUser) {  
//        // 检查用户是否已经存在  
//        userMapper.register(newUser);  
//        if (userExists(newUser.getUsername())) {  
//            return "User already exists"; // 返回用户已存在的信息  
//        } else {  
//            // 在这里执行注册逻辑，向数据库中添加新用户  
//            addUser(newUser);  
//            return "Registration successful"; // 返回注册成功信息  
//        }  
//    }  
}

5、创建(User) Controller类

package com.my.mysql.controller;  import com.my.mysql.entity.User;  
import com.my.mysql.service.UserService;  
import org.springframework.beans.factory.annotation.Autowired;  
import org.springframework.web.bind.annotation.*;  import java.util.List;  @RestController  
public class UserController {  @Autowired  UserService userService;  @GetMapping("/queryUserList")  public List<User> queryUserList(){  return userService.queryUserList();  }  @GetMapping ("/queryUserById")  public User queryUserById(int id){  return userService.queryUserById(id);  }  @GetMapping("/addUser")  public String addUser(User user){  return userService.addUser(user);  }  @GetMapping("/deleteUserById")  public String deleteUserById(int id){  return userService.deleteUserById(id);  }  
//    @PutMapping("/updateUser")  
//    public String updateUser(@RequestBody User user) {  
//        userService.updateUser(user);  
//        System.out.println("更新成功");  
//        return "更新成功";  
//    }  @PutMapping("/updateUser")  public String updateUser(@RequestBody User user) {  return userService.updateUser(user);  
}  
//    @PostMapping("/login")  
//    public String login(@RequestBody User user) {  
//        return userService.login(String name,String passwd);  
//    }  
//    @PostMapping("/register")  
//    public String register(@RequestBody User user) {  
//        return userService.register(user);  
//    }  }