spring结合mybatis多租户实现单库分表

实现单库分表-水平拆分

思路：student表数据量大，所以将其进行分表处理。一共有三个分表，分别是student0，student1，student2，在新增数据的时候，根据请求头中的meta-tenant参数决定数据存在哪张表。

数据库

1. 建立数据库study1

2. 在数据库中建表，分别为student，student0，student1，student2，四个表结构都一样，只是表名不一样

CREATE TABLE `student` (
  `id` int NOT NULL AUTO_INCREMENT,
  `name` varchar(50) DEFAULT NULL,
  `age` int DEFAULT NULL,
  `credit` varchar(14) DEFAULT NULL,
  `tenant_id` int DEFAULT NULL COMMENT '租户id',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci;

引入pom

<!-- https://mvnrepository.com/artifact/org.apache.shardingsphere/shardingsphere-jdbc-core-spring-boot-starter -->
<dependency>
    <groupId>org.apache.shardingsphere</groupId>
    <artifactId>shardingsphere-jdbc-core-spring-boot-starter</artifactId>
    <version>5.1.1</version>
</dependency>

配置文件application.yml

#单库分表
spring:
  main:
    allow-bean-definition-overriding: true
  shardingsphere:
    datasource:
      names: ds1
      ds1:
        type: com.alibaba.druid.pool.DruidDataSource
        driver-class-name: com.mysql.cj.jdbc.Driver
        url: jdbc:mysql://localhost:3306/study1?serverTimezone=UTC&useUnicode=true&characterEncoding=utf-8
        username: root
        password: root1234
    mode:
      type: Memory
      overwrite: true
    rules:
      sharding:
        tables:
          student:
            actual-data-nodes: ds1.student$->{0..2}
            key-generate-strategy:
              column: id
              key-generator-name: snowflake
        binding-tables:
          - student
        default-table-strategy:
          standard:
            sharding-algorithm-name: custom_inline
            sharding-column: tenant_id
        default-sharding-column: tenant_id
        sharding-algorithms:
          custom_inline:
            type: CLASS_BASED
            props:
              strategy: STANDARD
              algorithmClassName: com.cyy.config.TablePreciseShardingAlgorithm
    props:
      sql-show: true
tenant:
  enable: true #启用多租户
  column: tenant_id

实现标准分片算法接口

package com.cyy.config;

import org.apache.shardingsphere.sharding.api.sharding.standard.PreciseShardingValue;
import org.apache.shardingsphere.sharding.api.sharding.standard.RangeShardingValue;
import org.apache.shardingsphere.sharding.api.sharding.standard.StandardShardingAlgorithm;
import org.springframework.stereotype.Component;

import java.util.Collection;

/**
 * 标准分表算法
 */
@Component
public class TablePreciseShardingAlgorithm implements StandardShardingAlgorithm<Integer> {

    @Override
    public String doSharding(Collection<String> collection, PreciseShardingValue<Integer> preciseShardingValue) {
        String tableName = preciseShardingValue.getLogicTableName().toLowerCase() + (preciseShardingValue.getValue() %10);
        return tableName;
    }

    @Override
    public Collection<String> doSharding(Collection<String> collection, RangeShardingValue<Integer> rangeShardingValue) {
        return collection;
    }

    @Override
    public void init() {

    }

    @Override
    public String getType() {
        return null;
    }
}

配置租户上下文相关内容

用到的常量

package com.cyy.constant;


/**
 * 多租户相关的常量
 */
public class TenantConstant {
    public static final String META_TENANT_ID = "meta-tenant";
    public static final String META_TENANT_ID_PARAM = "tenantId";
    public static final Long TENANT_ID_DEFAULT = 1l;
}

定义租户上下文

package com.cyy.config;

/**
 * 定义租户上下文，通过上下文保存当前租户的信息
 */
public class TenantContextHolder {
    private static final ThreadLocal<Long> CONETXT_HOLDER = new ThreadLocal<>();

    public static void set(Long l){
        CONETXT_HOLDER.set(l);
    }

    public static Long getTenantId(){
        return CONETXT_HOLDER.get();
    }

    public static void remove(){
        CONETXT_HOLDER.remove();
    }
}

设置多租户的相关的属性

package com.cyy.config;

import lombok.Data;
import org.springframework.boot.context.properties.ConfigurationProperties;

import java.util.HashSet;
import java.util.Set;

@Data
/**
 * 将配置文件中的属性自动映射都Java对象的字段中
 * 指定配置文件中的配置项的前缀为tenant，简化@Vlue注解，不需要加很多的@Value
 */
@ConfigurationProperties(prefix = "tenant")
@Component
public class TenantProperties {

    //不需要加tenantid的mapper方法名
    public static Set<String> NOT_PROCEED = new HashSet<>();

    //不需要加tenentid的表名
    public static Set<String> NOT_TABLES = new HashSet<>();

    //是否开启多租户，读取的是配置文件中的tenant.enable的值，等价于@Value(${tenant.enable})
    private boolean enable = false;

    //多租户字段
    private String column = "tenant_id";
}

配置租户上下文拦截器

package com.cyy.interceptor;

import com.cyy.config.TenantContextHolder;
import com.cyy.config.TenantProperties;
import com.cyy.constant.TenantConstant;
import lombok.extern.slf4j.Slf4j;
import org.apache.commons.lang.StringUtils;
import org.springframework.stereotype.Component;
import org.springframework.web.servlet.HandlerInterceptor;

import javax.annotation.Resource;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * HandlerInterceptor是在handler处理请求之前或者之后执行的拦截器，可以对请求做预处理或者对响应结果做统一处理，实现日志记录或者权限认证等功能
 * HandlerInterceptor可以拦截所有的请求，也可以只拦截特定的亲故
 */
@Slf4j
@Component
public class TenantContextHandlerInterceptor implements HandlerInterceptor {

    @Resource
    private TenantProperties tenantProperties;

    public TenantContextHandlerInterceptor(){
    }

    /**
     * 在请求处理前设置租户上下文
     * @param request current HTTP request
     * @param response current HTTP response
     * @param handler chosen handler to execute, for type and/or instance evaluation
     * @return
     * @throws Exception
     */
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        log.info("=====对请求进行统一拦截=====");
        if (tenantProperties.isEnable()){
            //从请求头中获取tenantId
            String tenantId = request.getHeader(TenantConstant.META_TENANT_ID);
            if (StringUtils.isNotBlank(tenantId)){
                TenantContextHolder.set(Long.parseLong(tenantId));
            } else {
                TenantContextHolder.set(TenantConstant.TENANT_ID_DEFAULT);
            }
            log.info("获取到的租户id为：【{}】",TenantContextHolder.getTenantId());
        }
        return true;
    }

    /**
     * 请求处理完成之后的回调
     * @param request current HTTP request
     * @param response current HTTP response
     * @param handler handler (or {@link HandlerMethod}) that started asynchronous
     * execution, for type and/or instance examination
     * @param ex exception thrown on handler execution, if any
     * @throws Exception
     */
    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        TenantContextHolder.remove();
    }
}

将租户上下文拦截器添加到springmvc配置中

对服务器的所有请求进行拦截，从请求头的meta-tenant参数中获取tenant_id值，并设置租户id

package com.cyy.config;

import com.cyy.interceptor.TenantContextHandlerInterceptor;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

import javax.annotation.Resource;
import java.util.List;

/**
 * 通过实现WebMvcConfigurer接口，可以自定义springmvc的配置，例如添加拦截器
 */
@Configuration
public class CustomeConfig implements WebMvcConfigurer {

    @Resource
    private MappingJackson2HttpMessageConverter mappingJackson2HttpMessageConverter;

    /**
     * TenantContextHandlerInterceptor类本身就是一个Bean，在这块再次声明一个相同Bean的时候，会报错
     * 可以在配置文件中添加配置allow-bean-definition-overriding: true，允许bean定义覆盖
     * @return
     */
    @Bean("tenantContextHandlerInterceptor")
    public HandlerInterceptor customerInterceptor(){
        return new TenantContextHandlerInterceptor();
    }

    /**
     * 添加拦截器
     * @param registry
     */
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(customerInterceptor());
    }

    @Override
    public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
        converters.add(0,mappingJackson2HttpMessageConverter);
    }
}

配置mybatis的插件

继承多租户拦截器TenantLineInnerInterceptor

package com.cyy.interceptor;

import com.baomidou.mybatisplus.extension.plugins.handler.TenantLineHandler;
import com.baomidou.mybatisplus.extension.plugins.inner.TenantLineInnerInterceptor;
import com.cyy.config.TenantContextHolder;
import com.cyy.config.TenantProperties;
import org.apache.ibatis.executor.Executor;
import org.apache.ibatis.mapping.BoundSql;
import org.apache.ibatis.mapping.MappedStatement;
import org.apache.ibatis.session.ResultHandler;
import org.apache.ibatis.session.RowBounds;

import java.sql.SQLException;
import java.util.Objects;

/**
 * 继承多租户拦截器
 */
public class CustomTenantLineInnerInterceptor extends TenantLineInnerInterceptor {
    private TenantProperties tenantProperties;
    public TenantProperties getTenantProperties(){
        return tenantProperties;
    }
    public void setTenantProperties(TenantProperties tenantProperties){
        this.tenantProperties = tenantProperties;
    }

    @Override
    public void beforeQuery(Executor executor, MappedStatement ms, Object parameter, RowBounds rowBounds, ResultHandler resultHandler, BoundSql boundSql) throws SQLException {
        if (TenantProperties.NOT_PROCEED.stream().anyMatch(s -> s.equalsIgnoreCase(ms.getId()))){
            return;
        }
        if (Objects.isNull(TenantContextHolder.getTenantId())){
            return;
        }
        super.beforeQuery(executor, ms, parameter, rowBounds, resultHandler, boundSql);
    }

    public CustomTenantLineInnerInterceptor(final TenantProperties tenantProperties, final TenantLineHandler tenantLineHandler){
        super(tenantLineHandler);
        this.setTenantProperties(tenantProperties);
        this.setTenantLineHandler(tenantLineHandler);
    }
}

添加多租户拦截器到mybatisplus拦截器中

将多租户拦截器CustomTenantLineInnerInterceptor添加到MybatisPlusInterceptor的拦截器中

package com.cyy.config;

import com.baomidou.mybatisplus.annotation.DbType;
import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor;
import com.baomidou.mybatisplus.extension.plugins.handler.TenantLineHandler;
import com.baomidou.mybatisplus.extension.plugins.inner.BlockAttackInnerInterceptor;
import com.baomidou.mybatisplus.extension.plugins.inner.OptimisticLockerInnerInterceptor;
import com.baomidou.mybatisplus.extension.plugins.inner.PaginationInnerInterceptor;
import com.baomidou.mybatisplus.extension.plugins.inner.TenantLineInnerInterceptor;
import com.cyy.interceptor.CustomTenantLineInnerInterceptor;
import net.sf.jsqlparser.expression.Expression;
import net.sf.jsqlparser.expression.LongValue;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import javax.annotation.Resource;
import java.util.Objects;

@Configuration
@MapperScan("com.cyy.mapper")
public class MybatisPlusConfig {
    @Resource
    private TenantProperties tenantProperties;

    @Bean
    public MybatisPlusInterceptor mybatisPlusInterceptor(){
        MybatisPlusInterceptor mybatisPlusInterceptor = new MybatisPlusInterceptor();
        //添加多租户拦截器
        if (tenantProperties.isEnable()){
            mybatisPlusInterceptor.addInnerInterceptor(tenantLineInnerInterceptor());
        }

        //分页插件
        mybatisPlusInterceptor.addInnerInterceptor(new PaginationInnerInterceptor(DbType.MYSQL));
        //防止全表更新与删除插件
        mybatisPlusInterceptor.addInnerInterceptor(new BlockAttackInnerInterceptor());
        //乐观锁插件
        mybatisPlusInterceptor.addInnerInterceptor(new OptimisticLockerInnerInterceptor());
        return mybatisPlusInterceptor;

    }

    public TenantLineInnerInterceptor tenantLineInnerInterceptor(){
        return new CustomTenantLineInnerInterceptor(tenantProperties, new TenantLineHandler() {
            /**
             * 获取租户id
             * @return
             */
            @Override
            public Expression getTenantId() {
                Long tenantId = TenantContextHolder.getTenantId();
                if (Objects.nonNull(tenantId)){
                    return new LongValue(tenantId);
                }

                return null;
            }

            /**
             * 获取多租户的字段名
             * @return
             */
            @Override
            public String getTenantIdColumn() {
                return tenantProperties.getColumn();
            }

            /**
             * 根据表名判断是否忽略拼接多租户条件
             * @param tableName 表名
             * @return
             */
            @Override
            public boolean ignoreTable(String tableName) {
                return tenantProperties.NOT_TABLES.stream().anyMatch((t) -> t.equalsIgnoreCase(tableName));
            }
        });
    }
}

测试代码

测试数据插入的controller

package com.cyy.controller;

import com.cyy.domain.Student;
import com.cyy.service.StudentService;
import com.cyy.util.RoundRobinUtil;
import com.cyy.config.TenantContextHolder;
import org.springframework.http.ResponseEntity;
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 javax.annotation.Resource;

/**
 * 学生类控制器
 */
@RestController
@RequestMapping("/student")
public class StudentController {
    @Resource
    private StudentService studentService;

    /**
     * 多租户测试-插入一个用户
     */
    @PostMapping("/insert")
    public ResponseEntity insert(@RequestBody Student student){
        student.setTenantId(TenantContextHolder.getTenantId().intValue());
        int i = studentService.insert(student);
        if (i > 0){
            return ResponseEntity.ok("插入成功");
        }
        return ResponseEntity.ok("插入失败");
    }
}

请求参数

{
    "id": 3,
    "name": "孙三",
    "age": 3,
    "credit": "3"
}