目前线上很多SAAS系统，但是SAAS系统必须支持多租户，对于多租户有多种实现方式，当然不同的实现方式的成本也是不同的。这里我介绍一种最节省成本的实现方式，通过数据记录增加租户标识字段tenant_id的方式。但是每次对数据库操作都要带上租户标识tenant_id是非常不方便，很容易出错。一旦出错就是破坏了SAAS的数据隔离，出现非常严重的事故。本次介绍的Spring boot 2.x 集成Mybatis-plus 通过自动拦截SQL语句并自动填充租户标识tenant_id，

一、创建maven项目zircloud-tenant, pom文件如下：

<?xml version="1.0" encoding="UTF-8"?><project xmlns=";	xmlns:xsi=";	xsi:schemaLocation=" ;>	<modelVersion>4.0.0</modelVersion>	<parent>		<groupId>org.springframework.boot</groupId>		<artifactId>spring-boot-starter-parent</artifactId>		<version>2.6.2</version>		<relativePath /> <!-- lookup parent from repository -->	</parent>	<groupId>com.zircloud.tenant</groupId>	<artifactId>zircloud-tenant</artifactId>	<version>0.0.1-SNAPSHOT</version>	<name>zircloud-tenant</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.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>		<dependency>			<groupId>mysql</groupId>			<artifactId>mysql-connector-java</artifactId>			<scope>runtime</scope>		</dependency>		<dependency>			<groupId>com.baomidou</groupId>			<artifactId>mybatis-plus-boot-starter</artifactId>			<version>3.5.0</version>		</dependency>		<!-- alibaba的druid数据库连接池 -->		<dependency>			<groupId>com.alibaba</groupId>			<artifactId>druid-spring-boot-starter</artifactId>			<version>1.1.10</version>		</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>

项目结构如下：

二、创建Mybatis-plus 配置类 MybatisPlusConfig.java

Mybaits-plus 配置用于自动填充租户标识tenant_id, 忽略不需要填充租户标识tenant_id的数据库表

        package com.zircloud.tenant.config;import org.mybatis.spring.annotation.MapperScan;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Configuration;import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor;import com.baomidou.mybatisplus.extension.plugins.handler.TenantLineHandler;import com.baomidou.mybatisplus.extension.plugins.inner.TenantLineInnerInterceptor;import net.sf.jsqlparser.expression.Expression;import net.sf.jsqlparser.expression.LongValue;/** * @author test * @since 2022年1月10日 */@Configuration@MapperScan("com.zircloud.**.mapper.**")  //要扫描的mapper目录public class MybatisPlusConfig {	@Bean	public MybatisPlusInterceptor mybatisPlusInterceptor() {		MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();		interceptor.addInnerInterceptor(new TenantLineInnerInterceptor(new TenantLineHandler() {			@Override			public Expression getTenantId() {				Long tenantId = 1L; //租户标识，可以从服务上下文中获取，				return new LongValue(tenantId);			}			@Override			public boolean ignoreTable(String tableName) {				return !"user_info".equalsIgnoreCase(tableName); //配置要忽略多租户的数据库表			}		}));		return interceptor;	}}

三、创建的Service、Controller类，

创建的Service、Controller就不用手动填充租户标识tenant_id了

package com.zircloud.tenant.service.impl;import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;import com.zircloud.tenant.dto.UserInfoDto;import com.zircloud.tenant.entity.UserInfo;import com.zircloud.tenant.mapper.UserInfoMapper;import com.zircloud.tenant.service.UserInfoService;import org.springframework.beans.BeanUtils;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.stereotype.Service;/** * <p> * 服务实现类 * </p> * * @author test * @since 2022-01-06 */@Servicepublic class UserInfoServiceImpl extends ServiceImpl<UserInfoMapper, UserInfo> implements UserInfoService {			@Autowired	private UserInfoMapper mapper;	@Override	public UserInfoDto getUserByid(Integer id) {		UserInfo user = mapper.selectById(id);		if(user!=null) {			UserInfoDto dto = new UserInfoDto();			BeanUtils.copyProperties(user, dto);			return dto;		}		return null;	}	@Override	public UserInfoDto getUserByname(String name) {		QueryWrapper<UserInfo> queryWrapper = new QueryWrapper<UserInfo>();		queryWrapper.eq("name",name);				UserInfo user = mapper.selectOne(queryWrapper);		if(user!=null) {			UserInfoDto dto = new UserInfoDto();			BeanUtils.copyProperties(user, dto);			return dto;		}		return null;	}	@Override	public boolean creaate(UserInfoDto dto) {		if(dto!=null) {			UserInfo user = new UserInfo();			BeanUtils.copyProperties(dto, user);			return mapper.insert(user)>0;		}		return false;	}}

Controller

package com.zircloud.tenant.web;import javax.annotation.Resource;import org.springframework.web.bind.annotation.GetMapping;import org.springframework.web.bind.annotation.PathVariable;import org.springframework.web.bind.annotation.PostMapping;import org.springframework.web.bind.annotation.RequestBody;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RestController;import com.zircloud.tenant.dto.UserInfoDto;import com.zircloud.tenant.service.UserInfoService;/** * 用户管理 * @author test * */@RestController@RequestMapping("/v1/users")public class UserInfoController {		@Resource	private UserInfoService userInfoService;		/**	 * 根据ID查询用户	 * @param id	 * @return	 */	@GetMapping("/details/{id}")	public UserInfoDto getUserbyId(@PathVariable("id") Integer id) {		return userInfoService.getUserByid(id);	}		/**	 * 根据ID查询用户	 * @param id	 * @return	 */	@GetMapping("/query/{name}")	public UserInfoDto getUserbyname(@PathVariable("name") String name) {		return userInfoService.getUserByname(name);	}		/**	 * 创建用户	 * @param dto	 * @return	 */	@PostMapping("/create")	public boolean create(@RequestBody UserInfoDto dto) {		return userInfoService.creaate(dto);	}}

通过以上步骤就实现Mybatis-plus对多租户的支持。以后就不再需要手动填充租户标识了。

zircloud-tentant: 本项目是采用spring boot 2.x 集成 myabatis-plus 实现多租户