Spring boot 连接多数据源

1.application.yml中添加两个datasource

server:
  port: 8080
spring:
  application:
    name: king
  datasource:
    master:
      type: com.zaxxer.hikari.HikariDataSource
      jdbc-url: jdbc:mysql://localhost:3306/king?useUnicode=yes&characterEncoding=UTF-8&serverTimezone=UTC
      driver-class-name: com.mysql.cj.jdbc.Driver
      username: root
      password: 123456
      idle-timeout: 10000
      minimum-idle: 1
      maximum-pool-size: 10
      pool-name: master
      auto-commit: false
      connection-test-query: SELECT 1
    slave:
      type: com.zaxxer.hikari.HikariDataSource
      jdbc-url: jdbc:mysql://localhost:3306/king?useUnicode=yes&characterEncoding=UTF-8&serverTimezone=UTC
      driver-class-name: com.mysql.cj.jdbc.Driver
      username: root
      password: 123456
      idle-timeout: 10000
      minimum-idle: 1
      maximum-pool-size: 10
      pool-name: slave
      auto-commit: false
      connection-test-query: SELECT 1

2.手动初始化数据源masterDataSource

package cn.bj.king.config;

import com.zaxxer.hikari.HikariConfig;
import com.zaxxer.hikari.HikariDataSource;
import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionFactoryBean;
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 org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.jdbc.datasource.DataSourceTransactionManager;
import org.springframework.transaction.annotation.EnableTransactionManagement;

import javax.sql.DataSource;

/**
* @author ARongking
* @date 2019-03-28
*/
@Configuration
@EnableTransactionManagement
@MapperScan(basePackages = {"cn.bj.king.mapper.master"},
        sqlSessionFactoryRef = "masterSqlSessionFactory")
public class WriteDataSourceConfig {

    @Bean(name = "masterDataSource")
    @Primary
    @Qualifier("masterDataSource")
    public DataSource masterDataSource(@Qualifier("masterHikariConfig")HikariConfig hikariConfig) {
        System.out.println("实例化主库");
        HikariDataSource hikariDataSource=new HikariDataSource(hikariConfig);
        return hikariDataSource;
    }

    /**
    * 配置连接池信息
    * @return
    */
    @ConfigurationProperties(prefix = "spring.datasource.master")
    @Bean("masterHikariConfig")
    public HikariConfig masterHikariConfig(){
        HikariConfig hikariConfig=new HikariConfig();
        return hikariConfig;
    }

    /**
     * SqlSessionFactory配置
     *
     * @return
     * @throws Exception
     */
    @Bean(name = "masterSqlSessionFactory")
    @Primary
    public SqlSessionFactory masterSqlSessionFactory(@Qualifier("masterDataSource") DataSource dataSource) throws Exception {
        SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
        sqlSessionFactoryBean.setDataSource(dataSource);
        PathMatchingResourcePatternResolver resolver = new PathMatchingResourcePatternResolver();
        // 配置mapper文件位置
        sqlSessionFactoryBean.setMapperLocations(resolver.getResources("classpath:mapper/master/*.xml"));
        sqlSessionFactoryBean.setTypeAliasesPackage("cn.bj.king.entity");
        return sqlSessionFactoryBean.getObject();
    }

    /**
     * 配置事物管理器
     *
     * @return
     */
    @Bean(name = "masterTransactionManager")
    @Primary
    public DataSourceTransactionManager masterTransactionManager(@Qualifier("masterDataSource") DataSource dataSource) {
        DataSourceTransactionManager dataSourceTransactionManager = new DataSourceTransactionManager();
        dataSourceTransactionManager.setDataSource(dataSource);
        return dataSourceTransactionManager;
    }
}

3.手动初始化数据源ReadDataSource

package cn.bj.king.config;

import com.github.pagehelper.PageInterceptor;
import com.zaxxer.hikari.HikariConfig;
import com.zaxxer.hikari.HikariDataSource;
import org.apache.ibatis.plugin.Interceptor;
import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.beans.factory.annotation.Autowired;
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.core.env.Environment;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.jdbc.datasource.DataSourceTransactionManager;
import org.springframework.transaction.annotation.EnableTransactionManagement;

import javax.sql.DataSource;
import java.util.Properties;

@Configuration
@EnableTransactionManagement
@MapperScan(basePackages = {"cn.bj.king.mapper.slave"},
        sqlSessionFactoryRef = "slaveSqlSessionFactory")
public class ReadDataSourceConfig {

    @Autowired
    Environment environment;

    @Bean(name = "slaveDataSource")
    @Qualifier("slaveDataSource")
    public DataSource slaveDataSource(@Qualifier("slaveHikariConfig")HikariConfig hikariConfig) {
        System.out.println("实例化从库");
        HikariDataSource hikariDataSource=new HikariDataSource(hikariConfig);
        return hikariDataSource;
    }

    /**
     * 配置连接池信息
     * @return
     */
    @ConfigurationProperties(prefix = "spring.datasource.slave")
    @Bean("slaveHikariConfig")
    public HikariConfig slaveHikariConfig(){
        HikariConfig hikariConfig=new HikariConfig();
        return hikariConfig;
    }

    /**
     * SqlSessionFactory配置
     *
     * @return
     * @throws Exception
     */
    @Bean(name = "slaveSqlSessionFactory")
    public SqlSessionFactory slaveSqlSessionFactory(@Qualifier("slaveDataSource") DataSource dataSource) throws Exception {
        SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
        sqlSessionFactoryBean.setDataSource(dataSource);
        PathMatchingResourcePatternResolver resolver = new PathMatchingResourcePatternResolver();
        // 配置mapper文件位置
        sqlSessionFactoryBean.setMapperLocations(resolver.getResources("classpath:mapper/slave/*.xml"));
        sqlSessionFactoryBean.setTypeAliasesPackage("cn.bj.king.entity");
        return sqlSessionFactoryBean.getObject();
    }

    /**
     * 配置事物管理器
     *
     * @return
     */
    @Bean(name = "slaveTransactionManager")
    public DataSourceTransactionManager slaveTransactionManager(@Qualifier("slaveDataSource") DataSource dataSource) {
        DataSourceTransactionManager dataSourceTransactionManager = new DataSourceTransactionManager();
        dataSourceTransactionManager.setDataSource(dataSource);
        return dataSourceTransactionManager;
    }
}

4.测试启动是否正常初始化master和slave 两个数据源
5.这里需要注意几个地方：
    * 配置数据库连接池的时候，如果不是手动设置HikariConfig ，即通过Environment 去一个个获取数据库连接池在yml中的配置的话，数据库连接池的（idle-timeout，minimum-idle， maximum-pool-size，pool-name，auto-commit，connection-test-query）等，一定要与slave节点平级，不然 HikariConfig 是读取不到这些信息的。
    * 如果手动赋值HikariConfig 的话，那就没有什么限制了，写到哪里都行，只需要用Environment  去读取配置文件的值，手动设置到HikariConfig 就行了。