相关内容请参考 Mybatis-Plus文档 项目实例

依赖

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-test</artifactId>
    <scope>test</scope>
</dependency>
<dependency>
    <groupId>com.baomidou</groupId>
    <artifactId>mybatis-plus-boot-starter</artifactId>
    <version>3.5.1</version>
</dependency>
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <scope>runtime</scope>
</dependency>

application.properties配置

spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://127.0.0.1:3306/mybatisplus?useUnicode=true&characterEncoding=utf8&serverTimezone=Asia/Shanghai&useSSL=false&allowPublicKeyRetrieval=true
spring.datasource.username=root
spring.datasource.password=root

启动类添加扫描mapper

@MapperScan("com.it.mybatisplus.Mapper")

image

实体类

@TableName(“实体对应的数据表名”)

@TableId(“主键ID”)

package com.it.mybatisplus.entity;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableName;
/**
 * @Author: 羡羡
 * @Date: 2022/05/25/09:03
 */
@TableName("user")
public class User {
    @TableId
    public int id;
    public String name;
    public int age;
    public String email;
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    public String getEmail() {
        return email;
    }
    public void setEmail(String email) {
        this.email = email;
    }
    public User() {
    }
    public User(String name, int age, String email) {
        this.name = name;
        this.age = age;
        this.email = email;
    }
    public User(int id, String name, int age, String email) {
        this.id = id;
        this.name = name;
        this.age = age;
        this.email = email;
    }
    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", age=" + age +
                ", email='" + email + '\'' +
                '}';
    }
}

Mapper

package com.it.mybatisplus.Mapper;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.it.mybatisplus.entity.User;
import org.apache.ibatis.annotations.Mapper;
/**
 * @Author: 羡羡
 * @Date: 2022/05/25/09:05
 */
@Mapper
public interface UserMapper extends BaseMapper<User>{
//泛型是对应的实体
}

service

package com.it.mybatisplus.service;
import com.it.mybatisplus.entity.User;
import com.it.mybatisplus.tools.JsonResult;
/**
 * @Author: 羡羡
 * @Date: 2022/05/25/09:38
 */
public interface UserService {
    /**
     * 查询所有的数据
     * @return
     */
    public JsonResult seall();
    /**
     * 查询指定ID的数据
     * @param id
     * @return
     */
    public JsonResult seonuser(int id);
    /**
     * 添加一条记录
     * @param usr
     * @return
     */
    public JsonResult addone(User usr);
    /**
     * 删除一条
     * @param id
     * @return
     */
    public JsonResult delone(int id);

    /**
     * 修改数据
     * @param usr
     * @return
     */
    public JsonResult upone(User usr);
    /**
     * 统计所有
     * @return
     */
    public JsonResult counnumber();
    /**
     * like查询
     * @param name
     * @return
     */
    public JsonResult likelist(String name);
}

serviceimpl

package com.it.mybatisplus.service;
import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.it.mybatisplus.Mapper.UserMapper;
import com.it.mybatisplus.entity.User;
import com.it.mybatisplus.tools.JsonResult;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import java.util.List;
/**
 * @Author: 羡羡
 * @Date: 2022/05/25/09:40
 */
@Service
public class UserServiceImpl implements UserService{
    @Autowired
    UserMapper us;
    /**
     * 查询所有的数据
     * @return
     */
    @Override
    public JsonResult seall() {
        List<User> lis=us.selectList(null);
        return new JsonResult(200,"获取成功！",lis);
    }
    /**
     * 查询指定ID的数据
     * @param id
     * @return
     */
    @Override
    public JsonResult seonuser(int id) {
        User usenti=us.selectById(id);
        return new JsonResult(200,"获取成功！",usenti);
    }
    /**
     * 添加一条记录
     * @param usr
     * @return
     */
    @Override
    public JsonResult addone(User usr) {
        int adsu=us.insert(usr);
        if(adsu>0){
            return new JsonResult(200,"添加成功！");
        }else{
            return new JsonResult(500,"添加失败！");
        }
    }
    /**
     * 删除一条
     * @param id
     * @return
     */
    @Override
    public JsonResult delone(int id) {
        int desu=us.deleteById(id);
        if(desu>0){
            return new JsonResult(200,"删除成功！");
        }else{
            return new JsonResult(500,"删除失败！");
        }
    }
    /**
     * 修改数据
     * @param usr
     * @return
     */
    @Override
    public JsonResult upone(User usr) {
        int upsu=us.update(usr,null);
        if(upsu>0){
            return new JsonResult(200,"更新成功！");
        }else{
            return new JsonResult(500,"更新失败！");
        }
    }
    /**
     * 统计数量
     * @return
     */
    @Override
    public JsonResult counnumber() {
        int coun= Math.toIntExact(us.selectCount(null));
        return new JsonResult(200,"获取成功！",coun);
    }
    /**
     * like查询
     * @param name
     * @return
     */
    @Override
    public JsonResult likelist(String name) {
        QueryWrapper<User> qu=new QueryWrapper<>();
        qu.like("name",name);
        List<User> lis=us.selectList(qu);
        return new JsonResult(200,"查询成功！",lis);
    }
}

控制器

package com.it.mybatisplus.controller;
import com.it.mybatisplus.entity.User;
import com.it.mybatisplus.service.UserService;
import com.it.mybatisplus.tools.JsonResult;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;
/**
 * @Author: 羡羡
 * @Date: 2022/05/25/09:43
 */
@RestController
public class TestController {
    @Autowired
    UserService user;
    /**
     * 返回所有的数据
     * @return
     */
    @RequestMapping(path = "/index",method = RequestMethod.GET)
    public JsonResult test(){
        return  user.seall();
    }
    /**
     * 通过ID查询指定数据
     * @param id ID
     * @return
     */
    @RequestMapping(path = "/user/{id}",method = RequestMethod.GET)
    public JsonResult test2(@PathVariable("id") Integer id){
        return user.seonuser(id);
    }
    /**
     * 添加一条记录
     * @param usrn
     * @return
     */
    @RequestMapping(path = "/adduser",method = RequestMethod.POST)
    public JsonResult test3(User usrn){
        return user.addone(usrn);
    }

    /**
     * 删除一条记录
     * @param id
     * @return
     */
    @RequestMapping(path = "/del/{id}",method = RequestMethod.GET)
    public JsonResult test4(@PathVariable("id") Integer id){
        return  user.delone(id);
    }
    /**
     * 更新数据
     * @param usen
     * @return
     */
    @RequestMapping(path = "/upuser",method = RequestMethod.PUT)
    public JsonResult test5(User usen){
        return user.upone(usen);
    }
    /**
     * 统计数量
     * @return
     */
    @RequestMapping(path = "/coun",method = RequestMethod.GET)
    public JsonResult test6(){
        return  user.counnumber();
    }
    /**
     * 模糊查询like
     * @param name
     * @return
     */
    @RequestMapping(path = "/like/{name}",method = RequestMethod.GET)
    public JsonResult test7(@PathVariable("name") String name){
        return user.likelist(name);
    }
}