SpringBoot第28讲：SpringBoot集成MySQL - MyBatis-Plus方式

SpringBoot第28讲：SpringBoot集成MySQL - MyBatis-Plus方式

本文是SpringBoot第28讲，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。MyBatis-Plus在国内也有很多的用户，本文主要介绍MyBatis-Plus和SpringBoot的集成。

1、知识准备

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。

1.1、为什么会诞生MyBatis-Plus？

正如前文所述（SpringBoot第24讲：SpringBoot集成MySQL - MyBatis XML方式），为了更高的效率，出现了MyBatis-Plus这类工具，对MyBatis进行增强。

1. 考虑到MyBatis是半自动化ORM，MyBatis-Plus 启动即会自动注入基本 CURD，性能基本无损耗，直接面向对象操作; 并且内置通用 Mapper、通用 Service，仅仅通过少量配置即可实现单表大部分 CRUD 操作，更有强大的条件构造器，满足各类使用需求；总体上让其支持全自动化的使用方式（本质上借鉴了Hibernate思路）；
2. 考虑到Java8 Lambda（函数式编程）开始流行，MyBatis-Plus支持 Lambda 表达式，方便的编写各类查询条件，无需再担心字段写错；
3. 考虑到MyBatis还需要独立引入PageHelper分页插件，MyBatis-Plus支持了内置分页插件，同PageHelper一样基于 MyBatis 物理分页，开发者无需关心具体操作，配置好插件之后，写分页等同于普通 List 查询；
4. 考虑到自动化代码生成方式，MyBatis-Plus也支持了内置代码生成器，采用代码或者 Maven 插件可快速生成 Mapper、Model、 Service、Controller 层代码，支持模板引擎，更有超多自定义配置等您来使用；
5. 考虑到SQL性能优化等问题，MyBatis-Plus内置性能分析插件, 可输出 SQL 语句以及其执行时间，建议开发测试时启用该功能，能快速揪出慢查询；(能对慢查询做到聚类吗？)
6. 其它还有解决一些常见开发问题，比如支持主键自动生成，支持4 种主键策略（内含分布式唯一 ID 生成器 - Sequence），可自由配置，完美解决主键问题；以及内置全局拦截插件，提供全表 delete 、 update 操作智能分析阻断，也可自定义拦截规则，预防误操作

1.2、支持数据库

任何能使用 MyBatis 进行 CRUD, 并且支持标准 SQL 的数据库，具体支持情况如下：

• MySQL，Oracle，DB2，H2，HSQL，SQLite，PostgreSQL，SQLServer，Phoenix，Gauss ，ClickHouse，Sybase，OceanBase，Firebird，Cubrid，Goldilocks，csiidb
• 达梦数据库，虚谷数据库，人大金仓数据库，南大通用(华库)数据库，南大通用数据库，神通数据库，瀚高数据库

1.3、整体架构

• 

2、简单示例

这里沿用上一篇文章的数据库, 向你展示SpringBoot + MyBatis-Plus的使用等。

2.1、准备DB和依赖配置

创建MySQL的schema test_db, 导入SQL 文件如下

DROP TABLE IF EXISTS `tb_role`;
/*!40101 SET @saved_cs_client     = @@character_set_client */;
/*!40101 SET character_set_client = utf8 */;
CREATE TABLE `tb_role` (`id` int(11) NOT NULL AUTO_INCREMENT,`name` varchar(255) NOT NULL,`role_key` varchar(255) NOT NULL,`description` varchar(255) DEFAULT NULL,`create_time` datetime DEFAULT NULL,`update_time` datetime DEFAULT NULL,PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8;
/*!40101 SET character_set_client = @saved_cs_client */;--
-- Dumping data for table `tb_role`
--LOCK TABLES `tb_role` WRITE;
/*!40000 ALTER TABLE `tb_role` DISABLE KEYS */;
INSERT INTO `tb_role` VALUES (1,'admin','admin','admin','2021-09-08 17:09:15','2021-09-08 17:09:15');
/*!40000 ALTER TABLE `tb_role` ENABLE KEYS */;
UNLOCK TABLES;--
-- Table structure for table `tb_user`
--DROP TABLE IF EXISTS `tb_user`;
/*!40101 SET @saved_cs_client     = @@character_set_client */;
/*!40101 SET character_set_client = utf8 */;
CREATE TABLE `tb_user` (`id` int(11) NOT NULL AUTO_INCREMENT,`user_name` varchar(45) NOT NULL,`password` varchar(45) NOT NULL,`email` varchar(45) DEFAULT NULL,`phone_number` int(11) DEFAULT NULL,`description` varchar(255) DEFAULT NULL,`create_time` datetime DEFAULT NULL,`update_time` datetime DEFAULT NULL,PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8;
/*!40101 SET character_set_client = @saved_cs_client */;--
-- Dumping data for table `tb_user`
--LOCK TABLES `tb_user` WRITE;
/*!40000 ALTER TABLE `tb_user` DISABLE KEYS */;
INSERT INTO `tb_user` VALUES (1,'qiwenjie','123456','[e-mail]',1212121213,'afsdfsaf','2021-09-08 17:09:15','2021-09-08 17:09:15');
/*!40000 ALTER TABLE `tb_user` ENABLE KEYS */;
UNLOCK TABLES;--
-- Table structure for table `tb_user_role`
--DROP TABLE IF EXISTS `tb_user_role`;
/*!40101 SET @saved_cs_client     = @@character_set_client */;
/*!40101 SET character_set_client = utf8 */;
CREATE TABLE `tb_user_role` (`user_id` int(11) NOT NULL,`role_id` int(11) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
/*!40101 SET character_set_client = @saved_cs_client */;--
-- Dumping data for table `tb_user_role`
--LOCK TABLES `tb_user_role` WRITE;
/*!40000 ALTER TABLE `tb_user_role` DISABLE KEYS */;
INSERT INTO `tb_user_role` VALUES (1,1);
/*!40000 ALTER TABLE `tb_user_role` ENABLE KEYS */;
UNLOCK TABLES;

引入maven依赖

<dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>8.0.28</version>
</dependency>
<dependency><groupId>com.baomidou</groupId><artifactId>mybatis-plus-boot-starter</artifactId><version>3.5.1</version>
</dependency>

增加yml配置

spring:datasource:url: jdbc:mysql://localhost:3306/db_user?useSSL=false&autoReconnect=true&characterEncoding=utf8driver-class-name: com.mysql.cj.jdbc.Driverusername: rootpassword: qwj930828mybatis-plus:configuration:# 是否开启二级缓存cache-enabled: trueuse-generated-keys: truedefault-executor-type: REUSEuse-actual-param-name: true

2.2、定义dao

RoleDao

package springboot.mysql.mybatisplus.anno.dao;import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import springboot.mysql.mybatisplus.anno.entity.Role;/*** @author qiwenjie*/
public interface IRoleDao extends BaseMapper<Role> {
}

UserDao

package springboot.mysql.mybatisplus.anno.dao;import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import springboot.mysql.mybatisplus.anno.entity.User;
import springboot.mysql.mybatisplus.anno.entity.query.UserQueryBean;import java.util.List;/*** @author qiwenjie*/
public interface IUserDao extends BaseMapper<User> {List<User> findList(UserQueryBean userQueryBean);
}

这里你也同时可以支持 BaseMapper 方式和自己定义的xml的方法（比较适用于关联查询），比如 findList 是自定义xml配置

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="springboot.mysql.mybatisplus.anno.dao.IUserDao"><resultMap type="springboot.mysql.mybatisplus.anno.entity.User" id="UserResult"><id     property="id"       	column="id"      		/><result property="userName"     column="user_name"    	/><result property="password"     column="password"    	/><result property="email"        column="email"        	/><result property="phoneNumber"  column="phone_number"  	/><result property="description"  column="description"  	/><result property="createTime"   column="create_time"  	/><result property="updateTime"   column="update_time"  	/><collection property="roles" ofType="springboot.mysql.mybatisplus.anno.entity.Role"><result property="id" column="id"  /><result property="name" column="name"  /><result property="roleKey" column="role_key"  /><result property="description" column="description"  /><result property="createTime"   column="create_time"  	/><result property="updateTime"   column="update_time"  	/></collection></resultMap><sql id="selectUserSql">select u.id, u.password, u.user_name, u.email, u.phone_number, u.description, u.create_time, u.update_time, r.name, r.role_key, r.description, r.create_time, r.update_timefrom tb_user uleft join tb_user_role ur on u.id=ur.user_idinner join tb_role r on ur.role_id=r.id</sql><select id="findList" parameterType="springboot.mysql.mybatisplus.anno.entity.query.UserQueryBean" resultMap="UserResult"><include refid="selectUserSql"/>where u.id != 0<if test="userName != null and userName != ''">AND u.user_name like concat('%', #{user_name}, '%')</if><if test="description != null and description != ''">AND u.description like concat('%', #{description}, '%')</if><if test="phoneNumber != null and phoneNumber != ''">AND u.phone_number like concat('%', #{phoneNumber}, '%')</if><if test="email != null and email != ''">AND u.email like concat('%', #{email}, '%')</if></select>
</mapper> 

2.3、定义Service接口和实现类

UserService接口

package springboot.mysql.mybatisplus.anno.service;import com.baomidou.mybatisplus.extension.service.IService;
import springboot.mysql.mybatisplus.anno.entity.User;
import springboot.mysql.mybatisplus.anno.entity.query.UserQueryBean;
import java.util.List;/*** @author qiwenjie*/
public interface IUserService extends IService<User> {List<User> findList(UserQueryBean userQueryBean);
}

User Service的实现类

package springboot.mysql.mybatisplus.anno.service.impl;import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import org.springframework.stereotype.Service;
import springboot.mysql.mybatisplus.anno.dao.IUserDao;
import springboot.mysql.mybatisplus.anno.entity.User;
import springboot.mysql.mybatisplus.anno.entity.query.UserQueryBean;
import springboot.mysql.mybatisplus.anno.service.IUserService;import java.util.List;@Service
public class UserDoServiceImpl extends ServiceImpl<IUserDao, User> implements IUserService {@Overridepublic List<User> findList(UserQueryBean userQueryBean) {return baseMapper.findList(userQueryBean);}
}

Role Service 接口

package springboot.mysql.mybatisplus.anno.service;import com.baomidou.mybatisplus.extension.service.IService;
import springboot.mysql.mybatisplus.anno.entity.Role;
import springboot.mysql.mybatisplus.anno.entity.query.RoleQueryBean;import java.util.List;public interface IRoleService extends IService<Role> {List<Role> findList(RoleQueryBean roleQueryBean);
}

Role Service 实现类

package springboot.mysql.mybatisplus.anno.service.impl;import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import org.apache.commons.lang3.StringUtils;
import org.springframework.stereotype.Service;
import springboot.mysql.mybatisplus.anno.dao.IRoleDao;
import springboot.mysql.mybatisplus.anno.entity.Role;
import springboot.mysql.mybatisplus.anno.entity.query.RoleQueryBean;
import springboot.mysql.mybatisplus.anno.service.IRoleService;
import java.util.List;@Service
public class RoleDoServiceImpl extends ServiceImpl<IRoleDao, Role> implements IRoleService {@Overridepublic List<Role> findList(RoleQueryBean roleQueryBean) {return lambdaQuery().like(StringUtils.isNotEmpty(roleQueryBean.getName()), Role::getName, roleQueryBean.getName()).like(StringUtils.isNotEmpty(roleQueryBean.getDescription()), Role::getDescription, roleQueryBean.getDescription()).like(StringUtils.isNotEmpty(roleQueryBean.getRoleKey()), Role::getRoleKey, roleQueryBean.getRoleKey()).list();}
}

2.4、controller

User Controller

package springboot.mysql.mybatisplus.anno.controller;import io.swagger.annotations.ApiOperation;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
import springboot.mysql.mybatisplus.anno.entity.User;
import springboot.mysql.mybatisplus.anno.entity.query.UserQueryBean;
import springboot.mysql.mybatisplus.anno.entity.response.ResponseResult;
import springboot.mysql.mybatisplus.anno.service.IUserService;
import java.time.LocalDateTime;
import java.util.List;/*** @author qiwenjie*/
@RestController
@RequestMapping("/user")
public class UserController {@Autowiredprivate IUserService userService;/*** @param user user param* @return user*/@ApiOperation("Add/Edit User")@PostMapping("add")public ResponseResult<User> add(User user) {if (user.getId() == null) {user.setCreateTime(LocalDateTime.now());}user.setUpdateTime(LocalDateTime.now());userService.save(user);return ResponseResult.success(userService.getById(user.getId()));}/*** @return user list*/@ApiOperation("Query User One")@GetMapping("edit/{userId}")public ResponseResult<User> edit(@PathVariable("userId") Long userId) {return ResponseResult.success(userService.getById(userId));}/*** @return user list*/@ApiOperation("Query User List")@GetMapping("list")public ResponseResult<List<User>> list(UserQueryBean userQueryBean) {return ResponseResult.success(userService.findList(userQueryBean));}
}

Role Controller

package springboot.mysql.mybatisplus.anno.controller;import io.swagger.annotations.ApiOperation;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import springboot.mysql.mybatisplus.anno.entity.Role;
import springboot.mysql.mybatisplus.anno.entity.query.RoleQueryBean;
import springboot.mysql.mybatisplus.anno.entity.response.ResponseResult;
import springboot.mysql.mybatisplus.anno.service.IRoleService;
import java.util.List;/*** @author qiwenjie*/
@RestController
@RequestMapping("/role")
public class RoleController {@Autowiredprivate IRoleService roleService;/*** @return role list*/@ApiOperation("Query Role List")@GetMapping("list")public ResponseResult<List<Role>> list(RoleQueryBean roleQueryBean) {return ResponseResult.success(roleService.findList(roleQueryBean));}
}

2.5、分页配置

通过配置内置的MybatisPlusInterceptor拦截器。

package springboot.mysql.mybatisplus.anno.config;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;/*** MyBatis-plus configuration, add pagination interceptor.** @author qiwenjie*/
@Configuration
public class MyBatisConfig {/*** inject pagination interceptor.** @return pagination*/@Beanpublic PaginationInnerInterceptor paginationInnerInterceptor() {return new PaginationInnerInterceptor();}/*** add pagination interceptor.** @return MybatisPlusInterceptor*/@Beanpublic MybatisPlusInterceptor mybatisPlusInterceptor() {MybatisPlusInterceptor mybatisPlusInterceptor = new MybatisPlusInterceptor();mybatisPlusInterceptor.addInnerInterceptor(paginationInnerInterceptor());return mybatisPlusInterceptor;}
}

3、进一步理解

MyBatis-plus学习梳理

• 官方文档
• 官方案例
• 官方源码仓库
• Awesome Mybatis-Plus

3.1、比较好的实践

总结下开发的过程中比较好的实践

1、Mapper层：继承BaseMapper

public interface IRoleDao extends BaseMapper<Role> {
}

2、Service层：继承ServiceImpl并实现对应接口

public class RoleDoServiceImpl extends ServiceImpl<IRoleDao, Role> implements IRoleService {}

3、Lambda函数式查询

@Override
public List<Role> findList(RoleQueryBean roleQueryBean) {return lambdaQuery().like(StringUtils.isNotEmpty(roleQueryBean.getName()), Role::getName, roleQueryBean.getName()).like(StringUtils.isNotEmpty(roleQueryBean.getDescription()), Role::getDescription, roleQueryBean.getDescription()).like(StringUtils.isNotEmpty(roleQueryBean.getRoleKey()), Role::getRoleKey, roleQueryBean.getRoleKey()).list();
}

4、分页采用内置MybatisPlusInterceptor

/*** inject pagination interceptor.* @return pagination*/
@Bean
public PaginationInnerInterceptor paginationInnerInterceptor() {return new PaginationInnerInterceptor();
}/*** add pagination interceptor.* @return MybatisPlusInterceptor*/
@Bean
public MybatisPlusInterceptor mybatisPlusInterceptor() {MybatisPlusInterceptor mybatisPlusInterceptor = new MybatisPlusInterceptor();mybatisPlusInterceptor.addInnerInterceptor(paginationInnerInterceptor());return mybatisPlusInterceptor;
}

5、对于复杂的关联查询

可以配置原生xml方式, 在其中自定义ResultMap

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="springboot.mysql.mybatisplus.anno.dao.IUserDao"><resultMap type="springboot.mysql.mybatisplus.anno.entity.User" id="UserResult"><id     property="id"       	column="id"      		/><result property="userName"     column="user_name"    	/><result property="password"     column="password"    	/><result property="email"        column="email"        	/><result property="phoneNumber"  column="phone_number"  	/><result property="description"  column="description"  	/><result property="createTime"   column="create_time"  	/><result property="updateTime"   column="update_time"  	/><collection property="roles" ofType="springboot.mysql.mybatisplus.anno.entity.Role"><result property="id" column="id"  /><result property="name" column="name"  /><result property="roleKey" column="role_key"  /><result property="description" column="description"  /><result property="createTime"   column="create_time"  	/><result property="updateTime"   column="update_time"  	/></collection></resultMap><sql id="selectUserSql">select u.id, u.password, u.user_name, u.email, u.phone_number, u.description, u.create_time, u.update_time, r.name, r.role_key, r.description, r.create_time, r.update_timefrom tb_user uleft join tb_user_role ur on u.id=ur.user_idinner join tb_role r on ur.role_id=r.id</sql><select id="findList" parameterType="springboot.mysql.mybatisplus.anno.entity.query.UserQueryBean" resultMap="UserResult"><include refid="selectUserSql"/>where u.id != 0<if test="userName != null and userName != ''">AND u.user_name like concat('%', #{user_name}, '%')</if><if test="description != null and description != ''">AND u.description like concat('%', #{description}, '%')</if><if test="phoneNumber != null and phoneNumber != ''">AND u.phone_number like concat('%', #{phoneNumber}, '%')</if><if test="email != null and email != ''">AND u.email like concat('%', #{email}, '%')</if></select>
</mapper> 

3.2、除了分页插件之外还提供了哪些插件？

插件都是基于拦截器实现的，MyBatis-Plus提供了如下插件：

• 自动分页: PaginationInnerInterceptor
• 多租户: TenantLineInnerInterceptor
• 动态表名: DynamicTableNameInnerInterceptor
• 乐观锁: OptimisticLockerInnerInterceptor
• sql 性能规范: IllegalSQLInnerInterceptor
• 防止全表更新与删除: BlockAttackInnerInterceptor

4、示例源码

todo