2 Mybatis-Plus快速入门

2.1 准备环境

  • JDK 8+
  • Maven 3.5.4
  • IDEA 2020.3
  • MySQL5.7

2.2 创建数据库以及表

创建数据库并设置字符集为utf-8：

CREATE DATABASE `mp` CHARACTER SET 'utf8' COLLATE 'utf8_general_ci';

创建表和测试数据：

-- 创建测试表
CREATE TABLE `tb_user` (
`id` bigint(20) NOT NULL AUTO_INCREMENT COMMENT '主键ID',
`user_name` varchar(20) NOT NULL COMMENT '用户名',
`password` varchar(20) NOT NULL COMMENT '密码',
`name` varchar(30) DEFAULT NULL COMMENT '姓名',
`age` int(11) DEFAULT NULL COMMENT '年龄',
`email` varchar(50) DEFAULT NULL COMMENT '邮箱',
`birthday` datetime DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;
-- 插入测试数据
INSERT INTO `tb_user`(`id`,`user_name`,`password`,`name`,`age`,`email`,`birthday`) VALUES
(1,'zhangsan','123456','张三',18,'test1@yh.cn','2019-09-26 11:42:01'),
(2,'lisi','123456','李四',20,'test2@yh.cn','2019-10-01 11:42:08'),
(3,'wangwu','123456','王五',28,'test3@yh.cn','2019-10-02 11:42:14'),
(4,'zhaoliu','123456','赵六',21,'test4@yh.cn','2019-10-05 11:42:18'),
(5,'sunqi','123456','孙七',24,'test5@yh.cn','2019-10-14 11:42:23');

2.3 工程搭建

2.3.1 创建工程

创建maven工程，分别填写GroupId ArtifactId和Version，如下：

<groupId>yh.mp</groupId>
<artifactId>yh-mp-springboot</artifactId>
<version>1.0-SNAPSHOT</version>

2.3.2 导入依赖

导入maven依赖，由于本例采用Spring boot技术，使用mybatis-plus-boot-starter能与其便捷集成：

版本规划：

Spring boot： 2.2.10.RELEASE

mybatis-plus： 3.1.0

<?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 http://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>2.1.3.RELEASE</version>
    </parent>

    <groupId>com.glls.mp</groupId>
    <artifactId>glls-mp-sb</artifactId>
    <version>1.0-SNAPSHOT</version>

    <dependencies>
        <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>
        <!--简化代码的工具包-->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <!--mybatis‐plus的springboot支持-->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.1.0</version>
        </dependency>
        <!--mysql驱动-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.49</version>
        </dependency>
    </dependencies>
</project>

2.3.3 编写application.yaml

spring:
  application:
    name: laojun-mp-sb
  datasource:
    password: 123456
    username: root
    driver-class-name: com.mysql.jdbc.Driver
    url: jdbc:mysql://127.0.0.1:3306/mp?useUnicode=true&characterEncoding=UTF8&serverTimezone=Asia/Shanghai&useSSL=false
logging:
  level:
    root: debug

2.3.4 编写pojo

package com.glls.mp.pojo;

import com.baomidou.mybatisplus.annotation.TableField;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableName;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

import java.time.LocalDateTime;

/**
 * @ClassName : User
 * @Author : glls
 * @Date: 2021/2/19 14:42
 * @Description : 实体类
 */
@Data
@NoArgsConstructor
@AllArgsConstructor
@TableName("tb_user")
public class User {
    @TableId("ID")
    private Long id;
    @TableField("USER_NAME")
    private String userName; //驼峰命名,则无需注解
    @TableField("PASSWORD")
    private String password;
    @TableField("NAME")
    private String name;
    @TableField("AGE")
    private Integer age;
    @TableField("EMAIL")
    private String email;
    @TableField("BIRTHDAY")
    private LocalDateTime birthday;
}

@Data：lombok的注解，使用它可以省略getter/setter方法。

@NoArgsConstructor： 生成无参构造 方法

@AllArgsConstructor：生成所有参数构造 方法，参数顺序与属性定义顺序一致。

@TableName：指定表名

@TableId：指定主键名

@TableField：指定列名

2.3.5 编写mapper

package com.glls.mp.mapper;

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.glls.mp.pojo.User;

public interface UserMapper extends BaseMapper<User> {
}

2.3.6 编写启动类

package com.glls.mp;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
@MapperScan("com.glls.mp.mapper")
public class MyApplication {
    public static void main(String[] args) {
        SpringApplication.run(MyApplication.class,args);
    }
}

2.3.7 编写测试用例

编写UserMapper的测试用例 ，使用UserMapper查询用户列表。在test下创建测试类，包名为 cn.yh.mp。

package com.glls.mp.testmp;

import com.glls.mp.mapper.UserMapper;
import com.glls.mp.pojo.User;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

import javax.annotation.Resource;
import java.util.List;

@SpringBootTest
@RunWith(SpringRunner.class)
public class UserMapperTest {

    @Resource
    private UserMapper userMapper;

    @Test
    public void testSelect() {
        List<User> userList = userMapper.selectList(null);
        for (User user : userList) {
            System.out.println(user);
        }
    }
}

测试结果：

2021-02-19 14:50:15.339 DEBUG 1360 --- [           main] c.glls.mp.mapper.UserMapper.selectList   : ==>  Preparing: SELECT ID,USER_NAME,PASSWORD,NAME,AGE,EMAIL,BIRTHDAY FROM tb_user 
2021-02-19 14:50:15.374 DEBUG 1360 --- [           main] c.glls.mp.mapper.UserMapper.selectList   : ==> Parameters: 
2021-02-19 14:50:15.412 DEBUG 1360 --- [           main] c.glls.mp.mapper.UserMapper.selectList   : <==      Total: 5
2021-02-19 14:50:15.413 DEBUG 1360 --- [           main] org.mybatis.spring.SqlSessionUtils       : Closing non transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@7afb1741]
User(id=1, userName=zhangsan, password=123456, name=张三, age=18, email=test1@yh.cn, birthday=2019-09-26T11:42:01)
User(id=2, userName=lisi, password=123456, name=李四, age=20, email=test2@yh.cn, birthday=2019-10-01T11:42:08)
User(id=3, userName=wangwu, password=123456, name=王五, age=28, email=test3@yh.cn, birthday=2019-10-02T11:42:14)
User(id=4, userName=zhaoliu, password=123456, name=赵六, age=21, email=test4@yh.cn, birthday=2019-10-05T11:42:18)
User(id=5, userName=sunqi, password=123456, name=孙七, age=24, email=test5@yh.cn, birthday=2019-10-14T11:42:23)

3 常见配置