Mybatis-plus（Quick start）

2024-01-11 23:11:10

数据库准备

CREATE DATABASE /*!32312 IF NOT EXISTS*/`mybatis_plus` /*!40100 DEFAULT CHARACTER SET utf8 */ /*!80016 DEFAULT ENCRYPTION=‘N‘ */;

USE `mybatis_plus`;

/*Table structure for table `user` */

CREATE TABLE `user` (
`id` bigint NOT NULL COMMENT ‘主键ID‘,
`name` varchar(30) DEFAULT NULL COMMENT ‘姓名‘,
`age` int DEFAULT NULL COMMENT ‘年龄‘,
`email` varchar(50) DEFAULT NULL COMMENT ‘邮箱‘,
`create_time` datetime DEFAULT NULL,
`update_time` datetime DEFAULT NULL,
`version` int DEFAULT NULL,
`deleted` tinyint(1) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

/*Data for the table `user` */

insert into `user`(`id`,`name`,`age`,`email`,`create_time`,`update_time`,`version`,`deleted`) values (1,‘Jone‘,18,‘test1@baomidou.com‘,NULL,NULL,NULL,NULL),(2,‘Jack‘,80,‘test2@baomidou.com‘,NULL,‘2021-07-07 17:21:34‘,NULL,NULL),(3,‘Tom‘,28,‘test3@baomidou.com‘,NULL,NULL,NULL,NULL),(4,‘Sandy‘,21,‘test4@baomidou.com‘,NULL,NULL,NULL,NULL),(5,‘Billie‘,24,‘test5@baomidou.com‘,NULL,NULL,NULL,NULL),(1412694920736972801,‘lucy‘,30,‘lucy@QQ.com‘,NULL,NULL,NULL,NULL),(1412703613004230658,‘lucy1‘,30,‘lucy@QQ.com‘,‘2021-07-07 17:22:43‘,‘2021-07-07 17:22:43‘,NULL,NULL),(1412729620788572161,‘功放不败‘,200,‘lucy@QQ.com‘,‘2021-07-07 19:06:04‘,‘2021-07-07 19:08:41‘,2,NULL),(1412743075298000898,‘erhuo‘,30,‘lucy@QQ.com‘,‘2021-07-07 19:59:31‘,‘2021-07-07 19:59:31‘,1,1),(1412746872967577602,‘我是Helen‘,18,‘helen@sina.com‘,‘2021-07-07 20:14:37‘,‘2021-07-07 20:14:37‘,1,0);

基本环境搭建

新建一个Springboot项目，导入pom依赖（版本：2.2.1.RELEASE）

       <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>
                <exclusions>
                    <exclusion>
                        <groupId>org.junit.vintage</groupId>
                        <artifactId>junit-vintage-engine</artifactId>
                    </exclusion>
                </exclusions>
            </dependency>

            <!--mybatis-plus-->
            <dependency>
                <groupId>com.baomidou</groupId>
                <artifactId>mybatis-plus-boot-starter</artifactId>
                <version>3.0.5</version>
            </dependency>

            <!--mysql-->
            <dependency>
                <groupId>mysql</groupId>
                <artifactId>mysql-connector-java</artifactId>
            </dependency>

            <!--lombok用来简化实体类-->
            <dependency>
                <groupId>org.projectlombok</groupId>
                <artifactId>lombok</artifactId>
            </dependency>
            <dependency>
                <groupId>junit</groupId>
                <artifactId>junit</artifactId>
                <scope>test</scope>
            </dependency>
        </dependencies>

建立基本结构和配置框架

application.properties

spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/mybatis_plus?serverTimezone=GMT%2B8
spring.datasource.username=root
spring.datasource.password=1234
#mybatis日志
mybatis-plus.configuration.log-impl=org.apache.ibatis.logging.stdout.StdOutImpl
mybatis-plus.global-config.db-config.logic-delete-value=1
mybatis-plus.global-config.db-config.logic-not-delete-value=0
spring.profiles.active=dev

实体类

user.java，这里使用了Lombok，会自动生成get、set方法和toString方法，以及有参无参构造器

import com.baomidou.mybatisplus.annotation.*;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

import java.util.Date;

@NoArgsConstructor
@AllArgsConstructor
@Data
public class User {
    //@TableId(type = IdType.ID_WORKER)//mp自带策略，生成19位数值，数字使用这个
    private Long id;
    //@TableId(type = IdType.ID_WORKER_STR)//字符串使用这个
    private String name;
    private Integer age;
    private String email;
    @TableField(fill = FieldFill.INSERT)
    private Date createTime;
    @TableField(fill = FieldFill.INSERT_UPDATE)
    private Date updateTime;
    @Version
    @TableField(fill = FieldFill.INSERT)
    private Integer version;
    @TableLogic
    @TableField(fill = FieldFill.INSERT)
    private Integer deleted;

}

mapper

UserMapper.java，这里实体类的mapper不需要去写接口方法，只需要去继承BaseMapper<User>这个类，就可以了，通过@Repository将实体类接口注册到Spring中。

import com.atguigu.entity.User;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import org.apache.ibatis.annotations.Mapper;
import org.springframework.stereotype.Repository;

@Repository
public interface UserMapper extends BaseMapper<User> {
}

测试

测试之前要讲实体类接口注入到测试方法中。

查询操作

　　查询所有user信息，通过UserMapper调用selectList方法，这个方法是Mybatis-plus提供的，这个方法是用来查询多个用户的，参数部分就是要填写的条件，因为要查询所有user，所以条件null，如果要填写条件需要实现wrapper的子类，一般会实现QueryWrapper这个子类，然后调用wrapper中的方法，将条件设置到wrapper中，然后将wrapper放到selectList中，这样就设置好了条件查询。

@Autowired
private UserMapper userMapper;
    @Test
    void contextLoads() {
        List<User> users = userMapper.selectList(null);
        for (User user : users) {
            System.out.println(user);
        }
    }

插入操作

  @Autowired
    private UserMapper userMapper;

    @Test
    public void testInsert(){

        User user = new User();
        user.setName("Helen");
        user.setAge(18);
        user.setEmail("55317332@qq.com");

        int result = userMapper.insert(user);
        System.out.println(result); //影响的行数
        System.out.println(user); //id自动回填
    }

更新操作

    @Test
    public void testUpdateById(){

        User user = new User();
        user.setId(1L);
        user.setAge(28);

        int result = userMapper.updateById(user);
        System.out.println(result);

    }

删除操作

@Test
public void testSelectById(){

    User user = userMapper.selectById(1L);
    System.out.println(user);
}

Mybatis-plus（Quick start）

码农公寓

数据库准备

基本环境搭建