Spring boot 连接多数据源过程详解

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。

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