SpringBoot+Mybatis+MySQL实现增删改查-蒲公英云

新建项目

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DemoApplication

添加：

@MapperScan("com.example.demo.mapper")

一定要在com.example.demo后面指明是mapper文件夹

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application.properties：

注意：等号后面不要加引号

server.port=8081
spring.datasource.url=jdbc:mysql://localhost:3306/test?characterEncoding=utf-8&allowMultiQueries=true&serverTimezone=GMT%2B8
#不要加引号！
spring.datasource.username=root
spring.datasource.password=root
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

controller/UserController:

package com.example.demo.controller;
import com.example.demo.entity.User;
import com.example.demo.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import java.util.List;
@RestController
@RequestMapping("/user")
public class UserController {
    @Autowired
   private UserService userService;
    @GetMapping
    public List<User> findAll(){
        return userService.findAll();
    }
}

entity/User:

导入lombok，用@Data注解后，类就不用添加get、set这些麻烦操作了

package com.example.demo.entity;
import lombok.Data;
@Data
public class User {
    private Integer id;
    private String username;
    private String password;
}

mapper/UserMapper:

package com.example.demo.mapper;
import com.example.demo.entity.User;
import org.apache.ibatis.annotations.Select;
import java.util.List;
public interface UserMapper {
    @Select("select * from user")
    List<User> findAll();
}

service/UserService:

package com.example.demo.service;
import com.example.demo.entity.User;
import java.util.List;
public interface UserService {
    List<User> findAll();
}

service/UserServiceImpl:

package com.example.demo.service;
import com.example.demo.entity.User;
import com.example.demo.mapper.UserMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import java.util.List;
@Service
public class UserServiceImpl implements UserService {
    @Autowired
   UserMapper userMapper;
    @Override
    public List<User> findAll() {
        return userMapper.findAll();
    }
}

mysql数据库文件：

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启动项目，访问：http://localhost:8081/user

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这样就实现了查询功能。

接下来实现其他功能

controller/UserController:

package com.example.demo.controller;
import com.example.demo.entity.User;
import com.example.demo.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
import java.util.List;
@RestController
@RequestMapping("/user")
public class UserController {
    @Autowired
   private UserService userService;
    @GetMapping
    public List<User> getUsers(){
        return userService.findAll();
    }
    @PostMapping
    public String  addUser(@RequestBody User user){
        userService.addUser(user);
        return "success";
    }
    @PutMapping
    public String updateUser(@RequestBody User user){
        userService.updateUserById( user);
        return "success";
    }
    @DeleteMapping("/{id}")
    public String deleteUser(@PathVariable Integer id){
        userService.deleteUserById(id);
        return "success";
    }
    @GetMapping("/{id}")
    public User getUserById(@PathVariable Integer id){
        return userService.getUserById(id);
    }
    @GetMapping("/find")
    public User getUserByUsername(@RequestParam String username){
        return userService.getUserByUsername(username);
    }
    @GetMapping("/hello")
    public String hello(@RequestParam String name){
        return "hello:"+name;
    }
}

mapper/UserMapper:

package com.example.demo.mapper;
import com.example.demo.entity.User;
import org.apache.ibatis.annotations.Delete;
import org.apache.ibatis.annotations.Select;
import org.apache.ibatis.annotations.Update;
import org.springframework.transaction.annotation.Transactional;
import java.util.List;
public interface UserMapper {
    @Select("select * from user")
    List<User> findAll();
    @Update("INSERT INTO `user`(`username`, `password`) VALUES (#{username}, #{password})")
    @Transactional
    void addUser(User user);
    @Update("update user set username=#{username},password=#{password} where id=#{id}")
    @Transactional
    void updateUserById(User user);
    @Delete("delete from user where id=#{id}")
    @Transactional
    void deleteUserById(Integer id);
    @Select("select * from user where id=#{id}")
    User getUserById(Integer id);
    @Select("select * from user where username=#{username}")
    User getUserByUsername(String username);
}

service/UserService:

package com.example.demo.service;
import com.example.demo.entity.User;
import java.util.List;
public interface UserService {
    List<User> findAll();
    void addUser(User user);
    void updateUserById(User user);
    void deleteUserById(Integer id);
    User getUserById(Integer id);
    User getUserByUsername(String username);
}

service/UserServiceImpl:

package com.example.demo.service;
import com.example.demo.entity.User;
import com.example.demo.mapper.UserMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import java.util.List;
@Service
public class UserServiceImpl implements UserService {
    @Autowired
   UserMapper userMapper;
    @Override
    public List<User> findAll() {
        return userMapper.findAll();
    }
    @Override
    public void addUser(User user) {
        userMapper.addUser(user);
    }
    @Override
    public void updateUserById(User user) {
        userMapper.updateUserById(user);
    }
    @Override
    public void deleteUserById(Integer id) {
        userMapper.deleteUserById(id);
    }
    @Override
    public User getUserById(Integer id) {
      return userMapper.getUserById(id);
    }
    @Override
    public User getUserByUsername(String username) {
        return userMapper.getUserByUsername(username);
    }
}