MybatisPlus实现简单增删改查功能

实现步骤：

工具：IDEA
数据库版本：mysql5.7

一、环境搭建

1.创建springboot项目

pom.xml

2.pom.xml : spring web、lombok mysql

<dependencies>
  <dependency>
   <groupId>org.springframework.boot</groupId>
   <artifactId>spring-boot-starter-web</artifactId>
  </dependency>
  <dependency>
   <groupId>org.springframework.boot</groupId>
   <artifactId>spring-boot-devtools</artifactId>
   <scope>runtime</scope>
   <optional>true</optional>
  </dependency>
  <dependency>
   <groupId>mysql</groupId>
   <artifactId>mysql-connector-java</artifactId>
   <scope>runtime</scope>
  </dependency>
  <dependency>
   <groupId>org.projectlombok</groupId>
   <artifactId>lombok</artifactId>
   <optional>true</optional>
  </dependency>
  <dependency>
   <groupId>org.springframework.boot</groupId>
   <artifactId>spring-boot-starter-test</artifactId>
   <scope>test</scope>
  </dependency>
 </dependencies>

3.添加mybatisplus依赖

<dependency>
   <groupId>com.baomidou</groupId>
   <artifactId>mybatis-plus-boot-starter</artifactId>
   <version>3.3.1.tmp</version>
  </dependency>

application.properties

4.application.properties配置文件：用户名、密码、连接驱动、配置日志

注意：mysql8 需要增加时区的配置 serverTimezone=GMT%2B8 东八区

#mysql5 驱动不同
spring.datasource.username=root
spring.datasource.password=123456
spring.datasource.url=jdbc:mysql://localhost:3306/mybatisplus?useSSL=false&useUnicode=true&characterEncoding=utf-8
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

#配置日志
mybatis-plus.configuration.log-impl=org.apache.ibatis.logging.stdout.StdOutImpl

数据库数据

#建表
DROP TABLE IF EXISTS user;

CREATE TABLE user
(
	id BIGINT(20) NOT NULL COMMENT '主键ID',
	name VARCHAR(30) NULL DEFAULT NULL COMMENT '姓名',
	age INT(11) NULL DEFAULT NULL COMMENT '年龄',
	email VARCHAR(50) NULL DEFAULT NULL COMMENT '邮箱',
	PRIMARY KEY (id)
);

#插入数据
DELETE FROM user;

INSERT INTO user (id, name, age, email) VALUES
(1, 'Jone', 18, 'test1@baomidou.com'),
(2, 'Jack', 20, 'test2@baomidou.com'),
(3, 'Tom', 28, 'test3@baomidou.com'),
(4, 'Sandy', 21, 'test4@baomidou.com'),
(5, 'Billie', 24, 'test5@baomidou.com');

代码详解

1.新建实体类User
lombok注解详解：
@Data：自动生成get\set方法
@AllArgsConstructor ：有参方法
@NoArgsConstructor：无参方法
@TableId(value = “id”,type = IdType.AUTO) ：给实体设置自增

package com.sh.entity;

import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableId;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import org.springframework.context.annotation.Primary;

import java.util.Date;

@Data
@AllArgsConstructor
@NoArgsConstructor

public class User {
 @TableId(value = "id",type = IdType.AUTO)
 private Integer id;
 private String name;
 private Integer age;
 private String email;
 private Date createTime;
 private Date updateTime;
}

2. 新建mapper包
在mapper包里建UserMappe接口r 继承BaseMapper<实体类>

package com.sh.mapper;

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.sh.entity.User;
import org.springframework.stereotype.Repository;

@Repository
public interface UserMapper extends BaseMapper<User> {

}

3.创建控制层controller：
新建UserController类

package com.sh.controller;

import com.sh.entity.User;
import com.sh.mapper.UserMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

@RestController
public class UserController {
 @Autowired
 private UserMapper userMapper;
 //查询 查询所以 null 就是没有条件
 @GetMapping("/selectUser")
 public List<User> getAll(){
  List<User> user = userMapper.selectList(null);
  return user;
 }
 //根据id查询
 @GetMapping("/selectById")
 public User selectUserById(){
  User user = userMapper.selectById(1);
  return user;
 }
 //根据多个id查询 Arrays.asList集合
 @GetMapping("/selectByIds")
 public List<User> selectUserByIds(){
  List<User> user = userMapper.selectBatchIds(Arrays.asList(1,2,3));
  return user;
 }
 //添加
 @PostMapping("/insertUser")
 public Integer insertUsers(User user){
  Integer result = userMapper.insert(user);
  return result;
 }
 //修改 根据id
 @PutMapping("/updateUser")
 public Integer updateUsers(User user){
  Integer result = userMapper.updateById(user);
  return result;
 }
 //删除 根据id
 @DeleteMapping("/deleteUser")
 public Integer deleteUsers(Integer id){
  Integer result = userMapper.deleteById(id);
  return result;
 }
}

项目结构

注意：添加，修改操作需要数据库和实体设置自增

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