Java中SringBoot服务连接多个MySQL数据源案例实战

1.场景

A服务（供应商）有一套自己的数据库db1；B服务（二次开发）也有一套自己的数据库db2；从B服务查询db1中的一些数据，需要B服务同时链接2个数据库源。

2.取消默认的单数据源配置

修改启动类的@SpringBootApplication注解，（将org.example.db.**.mapper替换为自己项目的mapper文件目录）

@SpringBootApplication(exclude={DataSourceAutoConfiguration.class})
@MapperScan({"org.example.db1.**.mapper","org.example.db1.**.mapper"})
public class TestApplication{
	...
}

3.自定义多数据源配置文件

在application.properties 文件（或nacos配置文件）中配置以下数据库连接源：

spring:
  # 数据源配置
  datasource:
    db1:
      jdbc-url: xxxxxxxxxxxxxx
      username: xxxxxxxxxxxxxx
      password: xxxxxxxxxxxxxx
      type: com.alibaba.druid.pool.DruidDataSource
      driver-class-name: com.mysql.cj.jdbc.Driver
    db2:
      jdbc-url: xxxxxxxxxxxxxx
      username: xxxxxxxxxxxxxx
      password: xxxxxxxxxxxxxx
      type: com.alibaba.druid.pool.DruidDataSource
      driver-class-name: com.mysql.cj.jdbc.Driver

4.自定义多数据源配置类

1.DB1Config.java

将org.example.db1.**.mapper替换为自己项目的mapper文件目录

import com.baomidou.mybatisplus.annotation.DbType;
import com.baomidou.mybatisplus.annotation.FieldStrategy;
import com.baomidou.mybatisplus.core.MybatisConfiguration;
import com.baomidou.mybatisplus.core.config.GlobalConfig;
import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor;
import com.baomidou.mybatisplus.extension.plugins.inner.PaginationInnerInterceptor;
import com.baomidou.mybatisplus.extension.spring.MybatisSqlSessionFactoryBean;
import org.apache.ibatis.plugin.Interceptor;
import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionTemplate;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.jdbc.DataSourceBuilder;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;

import javax.sql.DataSource;

@Configuration
@MapperScan(basePackages = "org.example.db1.**.mapper",sqlSessionFactoryRef = "db1SqlSessionFactory")
public class DB1Config {
    
    @Primary
    @Bean(name = "db1DataSource")
    @ConfigurationProperties(prefix = "spring.datasource.db1")
    public DataSource initDataSource(){
        return DataSourceBuilder.create().build();
    }
    
    @Primary
    @Bean(name = "db1SqlSessionFactory")
    public SqlSessionFactory initSqlSessionFactory(@Qualifier("db1DataSource") DataSource dataSource) throws Exception {
        MybatisSqlSessionFactoryBean bean = new MybatisSqlSessionFactoryBean();
        bean.setDataSource(dataSource);
        GlobalConfig globalConfig = new GlobalConfig();
        globalConfig.setDbConfig(new GlobalConfig.DbConfig().setUpdateStrategy(FieldStrategy.IGNORED));
        bean.setGlobalConfig(globalConfig);
        MybatisConfiguration mybatisConfiguration = new MybatisConfiguration();
        mybatisConfiguration.setMapUnderscoreToCamelCase(false);
        bean.setConfiguration(mybatisConfiguration);
        bean.setPlugins(new Interceptor[]{mybatisPlusInterceptor()});
        SqlSessionFactory sessionFactory = bean.getObject();
        org.apache.ibatis.session.Configuration configuration = sessionFactory.getConfiguration();
        configuration.setMapUnderscoreToCamelCase(false);
        return sessionFactory;
    }

    @Primary
    @Bean(name = "db1mybatisPlusInterceptor")
    public Interceptor mybatisPlusInterceptor() {
        MybatisPlusInterceptor mybatisPlusInterceptor = new MybatisPlusInterceptor();
        mybatisPlusInterceptor.addInnerInterceptor(new PaginationInnerInterceptor(DbType.MYSQL));
        return mybatisPlusInterceptor;
    }
    
    
    @Primary
    @Bean(name = "db1DataSourceTransactionManager")
    public DataSourceTransactionManager initDataSourceTransactionManager(@Qualifier("db1DataSource") DataSource dataSource){
        return new DataSourceTransactionManager(dataSource);
    }

    @Primary
    @Bean(name = "db1SqlSessionTemplate")
    public SqlSessionTemplate initSqlSessionTemplate(@Qualifier("db1SqlSessionFactory")SqlSessionFactory sqlSessionFactory){
        return new SqlSessionTemplate(sqlSessionFactory);
    }
    
}

2.DB2Config.java

数据库 db2 的配置类要将 @Primary 注解去掉

import com.baomidou.mybatisplus.annotation.DbType;
import com.baomidou.mybatisplus.annotation.FieldStrategy;
import com.baomidou.mybatisplus.core.MybatisConfiguration;
import com.baomidou.mybatisplus.core.config.GlobalConfig;
import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor;
import com.baomidou.mybatisplus.extension.plugins.inner.PaginationInnerInterceptor;
import com.baomidou.mybatisplus.extension.spring.MybatisSqlSessionFactoryBean;
import org.apache.ibatis.plugin.Interceptor;
import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionTemplate;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.jdbc.DataSourceBuilder;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import javax.sql.DataSource;
@Configuration
@MapperScan(basePackages = "org.example.db2.**.mapper",sqlSessionFactoryRef = "db2SqlSessionFactory")
public class DB2Config {

    @Bean(name = "db2DataSource")
    @ConfigurationProperties(prefix = "spring.datasource.db2")
    public DataSource initDataSource(){
        return DataSourceBuilder.create().build();
    }
    
    @Bean(name = "db2SqlSessionFactory")
    public SqlSessionFactory initSqlSessionFactory(@Qualifier("db2DataSource") DataSource dataSource) throws Exception {
        MybatisSqlSessionFactoryBean bean = new MybatisSqlSessionFactoryBean();
        bean.setDataSource(dataSource);
        GlobalConfig globalConfig = new GlobalConfig();
        globalConfig.setDbConfig(new GlobalConfig.DbConfig().setUpdateStrategy(FieldStrategy.IGNORED));
        bean.setGlobalConfig(globalConfig);
        MybatisConfiguration mybatisConfiguration = new MybatisConfiguration();
        mybatisConfiguration.setMapUnderscoreToCamelCase(false);
        bean.setConfiguration(mybatisConfiguration);
        bean.setPlugins(new Interceptor[]{mybatisPlusInterceptor()});
        SqlSessionFactory sessionFactory = bean.getObject();
        org.apache.ibatis.session.Configuration configuration = sessionFactory.getConfiguration();
        configuration.setMapUnderscoreToCamelCase(false);
        return sessionFactory;
    }

  
    @Bean(name = "db2mybatisPlusInterceptor")
    public Interceptor mybatisPlusInterceptor() {
        MybatisPlusInterceptor mybatisPlusInterceptor = new MybatisPlusInterceptor();
        mybatisPlusInterceptor.addInnerInterceptor(new PaginationInnerInterceptor(DbType.MYSQL));
        return mybatisPlusInterceptor;
    }



    @Bean(name = "db2DataSourceTransactionManager")
    public DataSourceTransactionManager initDataSourceTransactionManager(@Qualifier("db2DataSource") DataSource dataSource){
        return new DataSourceTransactionManager(dataSource);
    }
    
    @Bean(name = "db2SqlSessionTemplate")
    public SqlSessionTemplate initSqlSessionTemplate(@Qualifier("db2SqlSessionFactory")SqlSessionFactory sqlSessionFactory){
        return new SqlSessionTemplate(sqlSessionFactory);
    }
}

5.启动项目，测试操作多数据源

项目启动后，控制台中看到以下内容即为配置成功

HikariPool-1 - Starting…
HikariPool-1 - Start completed.
HikariPool-2 - Starting…
HikariPool-2 - Start completed.