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

第一步、导入依赖

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.tiger</groupId>
    <artifactId>DoubleDataSource</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <maven.compiler.source>17</maven.compiler.source>
        <maven.compiler.target>17</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <!--    声明springboot的版本号 -->
        <spring-boot.version>2.5.5</spring-boot.version>
    </properties>

    <!--  引入springboot官方提供的所有依赖的版本号定义，如果项目中使用相关依赖，可以不必写版本号了-->
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-dependencies</artifactId>
                <version>${spring-boot.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <dependencies>
        <!--    引入springboot的web项目的依赖        -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <!-- 基于 mybatis plus 的dao层的相关依赖 start-->

        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.5.2</version>
        </dependency>


        <!-- 德鲁伊启动器     -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid-spring-boot-starter</artifactId>
            <version>1.2.6</version>
        </dependency>

        <!--    数据库依赖-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.47</version>
        </dependency>

        <!-- 基于 mybatis plus 的dao层的相关依赖 end-->

        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>dynamic-datasource-spring-boot-starter</artifactId>
            <version>3.3.2</version>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>

        <!--  springboot测试依赖   -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>


    </dependencies>


</project>

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<Student> {
}

package com.tiger.DoubleDataSourceApp.service;

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

public interface FirstStudentService extends IService<Student> {
}

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<FirstStudentMapper, Student> 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<Student> {


    boolean saveList(List<Student> 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<FirstStudentMapper, Student> implements SecondStudentService {


    @Override
    public boolean saveList(List<Student> 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<FirstStudentMapper, Student> implements FirstStudentService {


    @Autowired
    private SecondStudentService secondStudentService;

    @Override
    public int syncDataBase() {
        List<Student> 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<Student> list = this.list();
        System.out.println(list);
        DynamicDataSourceContextHolder.push("slave_1");
        List<Student> list1 = this.list();
        System.out.println(list1);
        DynamicDataSourceContextHolder.poll();
        DynamicDataSourceContextHolder.push("slave_1");
        List<Student> list2 = this.list();
        System.out.println(list2);
        DynamicDataSourceContextHolder.poll();
        DynamicDataSourceContextHolder.push("master");
        List<Student> list3 = this.list();
        System.out.println(list3);
        DynamicDataSourceContextHolder.clear();
        List<Student> 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