MyBatis-Plus （简称 MP）是一个 MyBatis 的增强工具，在 MyBatis 的基础上只做增强不做改变，为简化开发、提高效率而生。
文档
目录
一、引入坐标
<dependency> <groupId>com.baomidou</groupId> <artifactId>mybatis-plus-boot-starter</artifactId> <version>3.5.2</version> </dependency> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <scope>runtime</scope> </dependency>
其他版本 https://mvnrepository.com/artifact/com.baomidou/mybatis-plus-boot-starter
完整配置 pom.xml
<?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>2.7.7</version> <relativePath/> <!-- lookup parent from repository --> </parent> <groupId>com.example</groupId> <artifactId>demo</artifactId> <version>0.0.1-SNAPSHOT</version> <name>demo</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-web</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-devtools</artifactId> <scope>runtime</scope> <optional>true</optional> </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> <!-- https://mvnrepository.com/artifact/com.baomidou/mybatis-plus-boot-starter --> <dependency> <groupId>com.baomidou</groupId> <artifactId>mybatis-plus-boot-starter</artifactId> <version>3.5.2</version> </dependency> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <scope>runtime</scope> </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>
二、配置
1、数据源配置
application.yml
# DataSource Config spring: datasource: driver-class-name: com.mysql.cj.jdbc.Driver url: jdbc:mysql://127.0.0.1:3306/data?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone=Asia/Shanghai username: root password: 123456 mybatis-plus: configuration: # 开启SQL语句打印 log-impl: org.apache.ibatis.logging.stdout.StdOutImpl global-config: db-config: # 自增主键策略 id-type: AUTO
2、分页配置
package com.example.demo.config; import com.baomidou.mybatisplus.annotation.DbType; import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor; import com.baomidou.mybatisplus.extension.plugins.inner.PaginationInnerInterceptor; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; /** * mp的分页拦截器 */ @Configuration public class MybatisPlusConfig { /** * 新版mp **/ @Bean public MybatisPlusInterceptor mybatisPlusInterceptor() { MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor(); interceptor.addInnerInterceptor(new PaginationInnerInterceptor(DbType.MYSQL)); return interceptor; } }
3、创建数据表
在data数据库下创建表tb_user
CREATE TABLE `tb_user` ( `id` int NOT NULL AUTO_INCREMENT COMMENT '主键id', `name` varchar(20) COMMENT '主键id', `age` int DEFAULT NULL COMMENT '姓名', PRIMARY KEY (`id`) );
三、CURD测试
实体类
package com.example.demo.entity.domain; import com.baomidou.mybatisplus.annotation.TableName; import com.fasterxml.jackson.annotation.JsonProperty; import lombok.Data; /** * 数据库实体映射 */ @Data @TableName("tb_user") public class User { private Long id; private String name; private Integer age; }
Mapper
package com.example.demo.mapper; import com.baomidou.mybatisplus.core.mapper.BaseMapper; import com.example.demo.entity.domain.User; import org.apache.ibatis.annotations.Mapper; @Mapper public interface UserMapper extends BaseMapper<User> { }
IService
package com.example.demo.service; import com.baomidou.mybatisplus.extension.service.IService; import com.example.demo.entity.domain.User; public interface UserService extends IService<User> { }
ServiceImpl
package com.example.demo.service.impl; import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl; import com.example.demo.entity.domain.User; import com.example.demo.mapper.UserMapper; import com.example.demo.service.UserService; import org.springframework.stereotype.Service; @Service public class UserServiceImpl extends ServiceImpl<UserMapper, User> implements UserService { }
测试
package com.example.demo.service; import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper; import com.baomidou.mybatisplus.core.conditions.update.LambdaUpdateWrapper; import com.baomidou.mybatisplus.extension.plugins.pagination.Page; import com.example.demo.entity.domain.User; import org.junit.jupiter.api.Test; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.boot.test.context.SpringBootTest; import java.util.List; @SpringBootTest public class UserServiceTest { @Autowired private UserService userService; /** * 插入数据 */ @Test void testSave() { User user = new User(); user.setName("Tom"); user.setAge(20); userService.save(user); // INSERT INTO tb_user ( name, age ) VALUES ( ?, ? ) } /** * 字段更新 */ @Test void testUpdateById() { User user = new User(); user.setId(1L); user.setAge(22); // 仅更新非空的属性 userService.updateById(user); // UPDATE tb_user SET age=? WHERE id=? } /** * 部分字段更新 */ @Test void testUpdateFieldById() { LambdaUpdateWrapper<User> updateWrapper = new LambdaUpdateWrapper<>(); updateWrapper.eq(User::getId, 1); updateWrapper.set(User::getAge, 30); userService.update(updateWrapper); // UPDATE tb_user SET age=? WHERE (id = ?) } /** * 查询单条数据 */ @Test void testGetById() { User user = userService.getById(1L); // SELECT id,name,age FROM tb_user WHERE id=? System.out.println(user); // User(id=1, name=Tom, age=22) } /** * 查询多条数据 */ @Test void testSelect() { LambdaQueryWrapper<User> queryWrapper = new LambdaQueryWrapper<>(); queryWrapper.gt(User::getAge, 20); // 2次SQL，一次查总记录数，一次查具体数据 // public Page(long current, long size, boolean searchCount) Page<User> page = new Page<>(1, 10); userService.page(page, queryWrapper); // SELECT COUNT(*) AS total FROM tb_user WHERE (age > ?) // SELECT id,name,age FROM tb_user WHERE (age > ?) LIMIT ? long total = page.getTotal(); List<User> records = page.getRecords(); System.out.println(total); // 1 System.out.println(records); // [User(id=1, name=Tom, age=22)] } }
四、API数据接口
通过对象转换和字段转换，我们能很容易控制输入和输出
Controller
package com.example.demo.controller; import com.example.demo.entity.domain.User; import com.example.demo.entity.dto.UserDto; import com.example.demo.entity.vo.UserVo; import com.example.demo.service.UserService; import org.springframework.beans.BeanUtils; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.web.bind.annotation.*; @RestController public class UserController { @Autowired private UserService userService; @PostMapping("/api/user/getUserById") public UserVo getUserById(@RequestBody UserDto userDto) { System.out.println(userDto); User user = userService.getById(userDto.getId()); UserVo userVo = new UserVo(); BeanUtils.copyProperties(user, userVo); return userVo; } }
DTO
package com.example.demo.entity.dto; import com.fasterxml.jackson.annotation.JsonProperty; import lombok.Data; /** * 接收前端提交的数据 */ @Data public class UserDto { @JsonProperty("user_id") private Long id; }
VO
package com.example.demo.entity.vo; import com.fasterxml.jackson.annotation.JsonProperty; import lombok.Data; /** * 返回前端的数据 */ @Data public class UserVo { @JsonProperty("user_id") private Long id; private String name; @JsonProperty("name_label") private String nameLabel; public String getNameLabel() { return "[" + name + ']'; } private void setNameLabel() { } }
接口请求
POST http://localhost:8080/api/user/getUserById Content-Type: application/json { "user_id": 1 }
返回数据
{ "name": "Tom", "user_id": 1, "name_label": "[Tom]" }
完整代码: https://mouday.github.io/spring-boot-demo/
参考
