Springboot整合多数据源，Mybatis-plus,druid 的实现

第一步、导入依赖

    4.0.0

    com.tiger
    DoubleDataSource
    1.0-SNAPSHOT

    
        17
        17
        UTF-8
        
        2.5.5
    

    
    
        
            
                org.springframework.boot
                spring-boot-dependencies
                ${spring-boot.version}
                pom
                import
            
        
    

    
        
        
            org.springframework.boot
            spring-boot-starter-web
        

        

        
            com.baomidou
            mybatis-plus-boot-starter
            3.5.2
        


        
        
            com.alibaba
            druid-spring-boot-starter
            1.2.6
        

        
        
            mysql
            mysql-connector-java
            5.1.47
        

        

        
            com.baomidou
            dynamic-datasource-spring-boot-starter
            3.3.2
        
        
            org.projectlombok
            lombok
        

        
        
            org.springframework.boot
            spring-boot-starter-test
            test
        


    

第二步、yml文件

spring:
  autoconfigure:
    exclude: com.alibaba.druid.spring.boot.autoconfigure.DruidDataSourceAutoConfigure
  datasource:
    dynamic:
      primary: master #设置默认的数据源或者数据源组,默认值即为master
      datasource:
        master:
          username: root
          password: root
          driver-class-name: com.mysql.jdbc.Driver
          url: jdbc:mysql://192.168.52.130:3306/firstDB?useSSL=false&useUnicode=true&characterEncoding=utf8
          type: com.alibaba.druid.pool.DruidDataSource
        slave_1:
          username: root
          password: root
          driver-class-name: com.mysql.jdbc.Driver
          url: jdbc:mysql://192.168.52.130:3306/secondDB?useSSL=false&useUnicode=true&characterEncoding=utf8
          type: com.alibaba.druid.pool.DruidDataSource

        #......省略
        #以上会配置一个默认库master，一个组slave下有两个子库slave_1,slave_2

第三步、mapper service serviceImpl

package com.tiger.DoubleDataSourceApp.mapper;


import com.baomidou.dynamic.datasource.annotation.DS;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.tiger.DoubleDataSourceApp.pojo.Student;

public interface FirstStudentMapper extends BaseMapper {
}

package com.tiger.DoubleDataSourceApp.service;

import com.baomidou.mybatisplus.extension.service.IService;
import com.tiger.DoubleDataSourceApp.pojo.Student;

public interface FirstStudentService extends IService {
}

package com.tiger.DoubleDataSourceApp.service.impl;

import com.baomidou.dynamic.datasource.annotation.DS;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.tiger.DoubleDataSourceApp.mapper.FirstStudentMapper;
import com.tiger.DoubleDataSourceApp.pojo.Student;
import com.tiger.DoubleDataSourceApp.service.FirstStudentService;
import org.springframework.stereotype.Service;

@Service
@DS("master")
public class FirstStudentServiceImpl extends ServiceImpl implements FirstStudentService {
}

package com.tiger.DoubleDataSourceApp;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
@MapperScan(basePackages = "com.tiger.DoubleDataSourceApp.mapper")
public class DDSApplication {
    public static void main(String[] args) {
        SpringApplication.run(DDSApplication.class,args);
    }
}

如何在同一个方法中切换数据源？

DynamicDataSourceContextHolder.push("slave");//slave即数据源名称
//中间执行你的业务sql
DynamicDataSourceContextHolder.clear();

第四步、整合事务测试

package com.tiger.DoubleDataSourceApp.service;

import com.baomidou.mybatisplus.extension.service.IService;
import com.tiger.DoubleDataSourceApp.pojo.Student;

import java.util.List;

public interface SecondStudentService extends IService {


    boolean saveList(List list);
}

package com.tiger.DoubleDataSourceApp.service.impl;

import com.baomidou.dynamic.datasource.annotation.DS;
import com.baomidou.dynamic.datasource.toolkit.DynamicDataSourceContextHolder;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.tiger.DoubleDataSourceApp.mapper.FirstStudentMapper;
import com.tiger.DoubleDataSourceApp.pojo.Student;
import com.tiger.DoubleDataSourceApp.service.FirstStudentService;
import com.tiger.DoubleDataSourceApp.service.SecondStudentService;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import java.util.List;

@Service
@DS("slave_1")
@Transactional(rollbackFor = Exception.class)
public class SecondStudentServiceImpl extends ServiceImpl implements SecondStudentService {


    @Override
    public boolean saveList(List list) {
        boolean b = this.saveBatch(list);
        int i=1/0;
        return b;
    }
}

package com.tiger.DoubleDataSourceApp.service.impl;

import com.baomidou.dynamic.datasource.annotation.DS;
import com.baomidou.dynamic.datasource.toolkit.DynamicDataSourceContextHolder;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.tiger.DoubleDataSourceApp.mapper.FirstStudentMapper;
import com.tiger.DoubleDataSourceApp.pojo.Student;
import com.tiger.DoubleDataSourceApp.service.FirstStudentService;
import com.tiger.DoubleDataSourceApp.service.SecondStudentService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import java.util.List;

@Service
@DS("master")
public class FirstStudentServiceImpl extends ServiceImpl implements FirstStudentService {


    @Autowired
    private SecondStudentService secondStudentService;

    @Override
    public int syncDataBase() {
        List list = this.list();


        secondStudentService.saveList(list);


        return 0;
    }
}

package com.tiger.DoubleDataSourceApp.mapper;

import com.tiger.DoubleDataSourceApp.pojo.Student;
import com.tiger.DoubleDataSourceApp.service.FirstStudentService;
import lombok.AllArgsConstructor;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

import java.util.List;

import static org.junit.jupiter.api.Assertions.*;
@SpringBootTest
class SencondStudentMapperTest {


    @Autowired
    private FirstStudentMapper firstStudentMapper;
    @Autowired
    private FirstStudentService firstStudentService;

    @Test
    void name() {
       firstStudentService.syncDataBase();

    }

    @Test
    void test1() {
        firstStudentMapper.insert(new Student(null,"张三",3));
    }
}

经过测试能够回滚.

mapper上也能加,加了代理的对象,就是对应的数据源,但是最好是在serviceImpl方法上加,可以做事务处理

需要注意的是,不能再两个不同数据源里加事务,事务只能对应一个数据源.

   @Override
    @Transactional(rollbackFor = Exception.class)
    public int syncDataBase() {
        List list = this.list();
        System.out.println(list);
        DynamicDataSourceContextHolder.push("slave_1");
        List list1 = this.list();
        System.out.println(list1);
        DynamicDataSourceContextHolder.poll();
        DynamicDataSourceContextHolder.push("slave_1");
        List list2 = this.list();
        System.out.println(list2);
        DynamicDataSourceContextHolder.poll();
        DynamicDataSourceContextHolder.push("master");
        List list3 = this.list();
        System.out.println(list3);
        DynamicDataSourceContextHolder.clear();
        List list4 = this.list();
        System.out.println(list4);
        return 0;
    }

这样的结果,就是让这里面所有的都变成一个数据源

DynamicDataSourceContextHolder.poll();

DynamicDataSourceContextHolder.clear();

的区别

前者只是弹出当前数据源,然后使用标记的DS数据源

clear强制清楚本地数据源,直接用 master 数据源