使用Spring Boot整合Mybatis-Plus实现数据库的增删查改

1、准备数据库中的表及表中的数据

/*
SQLyog Ultimate v12.09 (64 bit)
MySQL - 5.6.11 : Database - mp

*********************************************************************

*/


/*!40101 SET NAMES utf8 */;

/*!40101 SET SQL_MODE=''*/;

/*!40014 SET @OLD_UNIQUE_CHECKS=@@UNIQUE_CHECKS, UNIQUE_CHECKS=0 */;
/*!40014 SET @OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS, FOREIGN_KEY_CHECKS=0 */;
/*!40101 SET @OLD_SQL_MODE=@@SQL_MODE, SQL_MODE='NO_AUTO_VALUE_ON_ZERO' */;
/*!40111 SET @OLD_SQL_NOTES=@@SQL_NOTES, SQL_NOTES=0 */;
CREATE DATABASE /*!32312 IF NOT EXISTS*/`mp` /*!40100 DEFAULT CHARACTER SET utf8 */;

USE `mp`;

/*Table structure for table `tbl_employee` */

DROP TABLE IF EXISTS `tbl_employee`;

CREATE TABLE `tbl_employee` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `last_name` varchar(50) DEFAULT NULL,
  `email` varchar(50) DEFAULT NULL,
  `gender` char(1) DEFAULT NULL,
  `age` int(11) DEFAULT NULL,
  `version` int(11) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=24 DEFAULT CHARSET=utf8;

/*Data for the table `tbl_employee` */

insert  into `tbl_employee`(`id`,`last_name`,`email`,`gender`,`age`,`version`) values (1,'Tom','tom@zou.com','1',22,1),(2,'Jerry','jerry@zou.com','0',25,1),(3,'Black','black@zou.com','1',30,1),(4,'White','white@zou.com','0',35,1),(14,'小邹','com@hq.cn','0',19,1),(18,'jack','mp@zou.com','1',22,1),(22,'abc','123@qq.com','1',23,2);

/*!40101 SET SQL_MODE=@OLD_SQL_MODE */;
/*!40014 SET FOREIGN_KEY_CHECKS=@OLD_FOREIGN_KEY_CHECKS */;
/*!40014 SET UNIQUE_CHECKS=@OLD_UNIQUE_CHECKS */;
/*!40111 SET SQL_NOTES=@OLD_SQL_NOTES */;

2、初始化一个springboot项目

如何初始化一个springboot项目？
点击https://blog.csdn.net/Zou_05/article/details/115869941

注：勾选Lombok插件，简化开发

3、在pom.xml中加入mybatis-plus及mysql数据库的依赖

<!--mybatis-plus相关依赖-->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.4.2</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>6.0.5</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.1.10</version>
        </dependency>

4、将application.properties文件修改为application.yml，并添加mysql数据库的连接信息（mp为我的数据库名）

server:
  port: 8081
  servlet:
    context-path: /
spring:
  datasource:
    username: root
    password: 123456
    url: jdbc:mysql://localhost:3306/mp?useUnicode=true&characterEncoding=utf-8&useSSL=true&serverTimezone=UTC
    type: com.alibaba.druid.pool.DruidDataSource
    driver-class-name: com.mysql.cj.jdbc.Driver

5、编写实体类（使用lombok简化代码）

@TableName指定数据库的表名

@TableId(type = IdType.AUTO)指定id为自增

package com.zou.demo1.entity;

import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableName;
import com.baomidou.mybatisplus.annotation.Version;
import lombok.Data;

/**
 * @author: 邹祥发
 * @date: 2021/4/21 08:49
 */
@Data
@TableName("tbl_employee")
public class User {

 @TableId(type = IdType.AUTO)
 private Integer id;

 private String lastName;
 private String email;
 private Integer gender;
 private Integer age;

 @Version
 private Integer version;
}

6、编写Mapper类

package com.zou.demo1.mapper;

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.zou.demo1.entity.User;

/**
 * @author: 邹祥发
 * @date: 2021/4/21 08:55
 */
public interface UserMapper extends BaseMapper<User> {
}

7、因测试需要加入一些依赖，完整的pom.xml如下：

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.4.5</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.zou</groupId>
    <artifactId>demo1</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>demo1</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>1.8</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </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>

        <!--mybatis-plus相关依赖-->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.4.2</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>6.0.5</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.1.10</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-test</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-test</artifactId>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <excludes>
                        <exclude>
                            <groupId>org.projectlombok</groupId>
                            <artifactId>lombok</artifactId>
                        </exclude>
                    </excludes>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>

8、进行功能测试

注：@MapperScan("com.zou.demo1.mapper")指定扫描的mapper包

（1）查询测试：

package com.zou.demo1.test;

import com.zou.demo1.entity.User;
import com.zou.demo1.mapper.UserMapper;
import org.junit.Assert;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;

import java.util.List;

/**
 * @author: 邹祥发
 * @date: 2021/4/21 08:57
 */
@RunWith(SpringRunner.class)
@SpringBootTest
@MapperScan("com.zou.demo1.mapper")
public class SampleTest {

    @Autowired
    private UserMapper userMapper;

    @Test
    public void selectTest() {
        System.out.println(("----- selectAll method test ------"));
        List<User> userList = userMapper.selectList(null);
        Assert.assertEquals(7, userList.size());
        userList.forEach(System.out::println);
    }
}

测试结果：

（2）插入测试：

@Test
public void insertTest(){
    System.out.println(("----- insertOne method test ------"));
    User user = new User();
    user.setLastName("uzi");
    user.setEmail("uzi@qq.com");
    user.setGender(0);
    user.setAge(24);
    user.setVersion(1);
    int i = userMapper.insert(user);
    System.out.println(i);
}

测试结果：

（3）更新测试：

注：不能设置version的值（因为没有引入乐观锁的插件），否则会抛出mybatis-plus乐观锁异常

 <!--乐观锁插件-->
 <bean class="com.baomidou.mybatisplus.plugins.OptimisticLockerInterceptor"/>

具体配置请点击：
https://mp.baomidou.com/guide/interceptor-optimistic-locker.html#optimisticlockerinnerinterceptor

@Test
public void updateTest(){
    System.out.println(("----- updateOneById method test ------"));
    User user = new User();
    user.setId(24);
    user.setLastName("mlxg");
    user.setEmail("mlxg@qq.com");
    user.setGender(1);
    user.setAge(23);
    int i = userMapper.updateById(user);
    System.out.println(i);
}

测试结果：

（4）删除测试：

@Test
public void deleteTest(){
    System.out.println(("----- deleteOneById method test ------"));
    int i = userMapper.deleteById(24);
    System.out.println(i);
}

测试结果：