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。
文章目录
- [SpringBoot第28讲：SpringBoot集成MySQL - MyBatis-Plus方式](#SpringBoot第28讲：SpringBoot集成MySQL - MyBatis-Plus方式)
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。
- 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）；
- 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；
- 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；
- 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；
- 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？)
- 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
sql
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','1172814226@qq.com',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
xml
<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
yaml
spring:
datasource:
url: jdbc:mysql://localhost:3306/db_user?useSSL=false&autoReconnect=true&characterEncoding=utf8
driver-class-name: com.mysql.cj.jdbc.Driver
username: root
password: qwj930828
mybatis-plus:
configuration:
# 是否开启二级缓存
cache-enabled: true
use-generated-keys: true
default-executor-type: REUSE
use-actual-param-name: true2.2、定义dao
RoleDao
java
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
java
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
<?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_time
from tb_user u
left join tb_user_role ur on u.id=ur.user_id
inner 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
java
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
java
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 {
@Override
public List<User> findList(UserQueryBean userQueryBean) {
return baseMapper.findList(userQueryBean);
}
}Role Service 接口
java
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
java
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 {
@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();
}
}2.4、controller
User Controller
java
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 {
@Autowired
private 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
java
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 {
@Autowired
private 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。
java
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
*/
@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;
}
}3、进一步理解
MyBatis-plus学习梳理
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
java
public interface IRoleDao extends BaseMapper<Role> {
}2、Service层：继承ServiceImpl并实现对应接口
java
public class RoleDoServiceImpl extends ServiceImpl<IRoleDao, Role> implements IRoleService {
}3、Lambda函数式查询
java
@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
java
/**
* 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
<?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_time
from tb_user u
left join tb_user_role ur on u.id=ur.user_id
inner 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