Spring+MyBatis多数据源配置实现示例

最近用到了MyBatis配置多数据源，原以为简单配置下就行了，实际操作后发现还是要费些事的，这里记录下，以作备忘

不多废话，直接上代码，后面会有简单的实现介绍

jdbc和log4j的配置

#定义输出格式
ConversionPattern=%d %-5p [%t] %c - %m%n

log4j.rootLogger=DEBUG,Console
log4j.logger.com.cnblogs.lzrabbit=DEBUG
log4j.logger.org.springframework=ERROR
log4j.logger.org.mybatis=ERROR
log4j.logger.org.apache.ibatis=ERROR
log4j.logger.org.quartz=ERROR
log4j.logger.org.apache.axis2=ERROR
log4j.logger.org.apache.axiom=ERROR
log4j.logger.org.apache=ERROR
log4j.logger.httpclient=ERROR
#log4j.additivity.org.springframework=false
#Console 
log4j.appender.Console=org.apache.log4j.ConsoleAppender
log4j.appender.Console.Threshold=DEBUG 
log4j.appender.Console.Target=System.out 
log4j.appender.Console.layout=org.apache.log4j.PatternLayout 
log4j.appender.Console.layout.ConversionPattern=${ConversionPattern}
#log4j.appender.Console.encoding=UTF-8

#org.apache.log4j.DailyRollingFileAppender
log4j.appender.DailyFile=org.apache.log4j.DailyRollingFileAppender
log4j.appender.DailyFile.DatePattern='.'yyyy-MM-dd'.log'
log4j.appender.DailyFile.File=${myApp.root}/logs/daily.log
log4j.appender.DailyFile.Append=true
log4j.appender.DailyFile.Threshold=DEBUG
log4j.appender.DailyFile.layout=org.apache.log4j.PatternLayout
log4j.appender.DailyFile.layout.ConversionPattern=${ConversionPattern}
log4j.appender.DailyFile.encoding=UTF-8

# %c 输出日志信息所属的类的全名 
# %d 输出日志时间点的日期或时间，默认格式为ISO8601，也可以在其后指定格式，比如：%d{yyy-MM-dd HH:mm:ss}，输出类似：2002-10-18- 22：10：28
# %f 输出日志信息所属的类的类名 
# %l 输出日志事件的发生位置，即输出日志信息的语句处于它所在的类的第几行 
# %m 输出代码中指定的信息，如log(message)中的message 
# %n 输出一个回车换行符，Windows平台为“rn”，Unix平台为“n” 
# %p 输出优先级，即DEBUG，INFO，WARN，ERROR，FATAL。如果是调用debug()输出的，则为DEBUG，依此类推 
# %r 输出自应用启动到输出该日志信息所耗费的毫秒数 
# %t 输出产生该日志事件的线程名

#============================================================================
# MySQL
#============================================================================
jdbc.mysql.driver=com.mysql.jdbc.Driver
jdbc.mysql.url=jdbc:mysql://127.0.0.1:3306/test?useUnicode=true&characterEncoding=UTF-8&allowMultiQueries=true
jdbc.mysql.username=root
jdbc.mysql.password=root

#============================================================================
# MS SQL Server
#============================================================================
#jdbc.sqlserver.driver=com.microsoft.sqlserver.jdbc.SQLServerDriver
#jdbc.sqlserver.url=jdbc:sqlserver://127.0.0.1:1433;database=test;
#jdbc.sqlserver.username=sa
#jdbc.sqlserver.password=sa

#============================================================================
# MS SQL Server (JTDS)
#============================================================================
jdbc.sqlserver.driver=net.sourceforge.jtds.jdbc.Driver
jdbc.sqlserver.url=jdbc:jtds:sqlserver://127.0.0.1:1433/test
jdbc.sqlserver.username=sa
jdbc.sqlserver.password=sa


#============================================================================
# 通用配置
#============================================================================
jdbc.initialSize=5
jdbc.minIdle=5
jdbc.maxIdle=20
jdbc.maxActive=100
jdbc.maxWait=100000
jdbc.defaultAutoCommit=false
jdbc.removeAbandoned=true
jdbc.removeAbandonedTimeout=600
jdbc.testWhileIdle=true
jdbc.timeBetweenEvictionRunsMillis=60000
jdbc.numTestsPerEvictionRun=20
jdbc.minEvictableIdleTimeMillis=300000

单数据源时的Spring配置文件

多数据源时Spring配置文件

MultipleDataSource实现

package com.cnblogs.lzrabbit;

import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;

/**
 * Created by rabbit on 14-5-25.
 */
public class MultipleDataSource extends AbstractRoutingDataSource {
 private static final ThreadLocal dataSourceKey = new InheritableThreadLocal();

 public static void setDataSourceKey(String dataSource) {
  dataSourceKey.set(dataSource);
 }

 @Override
 protected Object determineCurrentLookupKey() {
  return dataSourceKey.get();
 }
}

MyBatis接口Mapper定义，直接使用注解方式实现

public interface MySqlMapper {
 @Select("select * from MyTable")
 List> getList();
}

public interface SqlServerMapper {
  @Select("select * from MyTable")
  List> getList();
}

手动数据源切换调用

package com.cnblogs.lzrabbit;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

/**
 * Created by rabbit on 14-5-25.
 */
public class Main {
 public static void main(String[] args) {
  //初始化ApplicationContext
  ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");

  MySqlMapper mySqlMapper = applicationContext.getBean(MySqlMapper.class);

  SqlServerMapper sqlServerMapper = applicationContext.getBean(SqlServerMapper.class);
  
  //设置数据源为MySql,使用了AOP测试时请将下面这行注释
  MultipleDataSource.setDataSourceKey("mySqlDataSource");
  mySqlMapper.getList();
  //设置数据源为SqlServer,使用AOP测试时请将下面这行注释
  MultipleDataSource.setDataSourceKey("sqlServerDataSource");
  sqlServerMapper.getList();
 }
}

使用SpringAOP方式实现自动切换

package com.cnblogs.lzrabbit;

import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.springframework.stereotype.Component;

@Component
@Aspect
public class MultipleDataSourceAspectAdvice {

 @Around("execution(* com.cnblogs.lzrabbit.*.*(..))")
 public Object doAround(ProceedingJoinPoint jp) throws Throwable {
  if (jp.getTarget() instanceof MySqlMapper) {
   MultipleDataSource.setDataSourceKey("mySqlDataSource");
  } else if (jp.getTarget() instanceof SqlServerMapper) {
   MultipleDataSource.setDataSourceKey("sqlServerDataSource");
  }
  return jp.proceed();
 }
}

调用日志

2014-05-25 20:02:04,319 DEBUG [main] com.jb51.lzrabbit.MySqlMapper.getList - ooo Using Connection [jdbc:mysql://127.0.0.1:3306/test?useUnicode=true&characterEncoding=UTF-8&allowMultiQueries=true, [email protected], MySQL Connector Java]
2014-05-25 20:02:04,333 DEBUG [main] com.jb51.lzrabbit.MySqlMapper.getList - ==> Preparing: select * from MyTable 
2014-05-25 20:02:04,371 DEBUG [main] com.jb51.lzrabbit.MySqlMapper.getList - ==> Parameters: 
2014-05-25 20:02:04,396 DEBUG [main] com.jb51.lzrabbit.MySqlMapper.getList - <==  Total: 8
2014-05-25 20:02:04,620 DEBUG [main] com.jb51.lzrabbit.SqlServerMapper.getList - ooo Using Connection [jdbc:jtds:sqlserver://127.0.0.1:1433/test, UserName=sa, jTDS Type 4 JDBC Driver for MS SQL Server and Sybase]
2014-05-25 20:02:04,620 DEBUG [main] com.jb51.lzrabbit.SqlServerMapper.getList - ==> Preparing: select * from TmallCityMap 
2014-05-25 20:02:04,621 DEBUG [main] com.jb51.lzrabbit.SqlServerMapper.getList - ==> Parameters: 
2014-05-25 20:02:04,681 DEBUG [main] com.jb51.lzrabbit.SqlServerMapper.getList - <==  Total: 397

这里就上面的实现做个简单解释，在我们配置单数据源时可以看到数据源类型使用了org.apache.commons.dbcp.BasicDataSource，而这个代码实现了javax.sql.DataSource接口

配置sqlSessionFactory时org.mybatis.spring.SqlSessionFactoryBean注入参数dataSource类型就是javax.sql.DataSource

实现多数据源的方法就是我们自定义了一个MultipleDataSource，这个类继承自AbstractRoutingDataSource，而AbstractRoutingDataSource继承自AbstractDataSource ，AbstractDataSource 实现了javax.sql.DataSource接口，所以我们的MultipleDataSource也实现了javax.sql.DataSource接口，可以赋值给sqlSessionFactory的dataSource属性

public abstract class AbstractRoutingDataSource extends AbstractDataSource implements InitializingBean {}

public abstract class AbstractDataSource implements DataSource {}

再来说下MultipleDataSource的实现原理，MultipleDataSource实现AbstractRoutingDataSource抽象类，然后实现了determineCurrentLookupKey方法，这个方法用于选择具体使用targetDataSources中的哪一个数据源

可以看到Spring配置中multipleDataSource设置了两个属性defaultTargetDataSource和targetDataSources，这两个属性定义在AbstractRoutingDataSource，当MyBatis执行查询时会先选择数据源，选择顺序时现根据determineCurrentLookupKey方法返回的值到targetDataSources中去找，若能找到怎返回对应的数据源，若找不到返回默认的数据源defaultTargetDataSource，具体参考AbstractRoutingDataSource的源码

public abstract class AbstractRoutingDataSource extends AbstractDataSource implements InitializingBean {

 private Map targetDataSources;

 private Object defaultTargetDataSource;

 
 /**
  * Retrieve the current target DataSource. Determines the
  * {@link #determineCurrentLookupKey() current lookup key}, performs
  * a lookup in the {@link #setTargetDataSources targetDataSources} map,
  * falls back to the specified
  * {@link #setDefaultTargetDataSource default target DataSource} if necessary.
  * @see #determineCurrentLookupKey()
  */
 protected DataSource determineTargetDataSource() {
  Assert.notNull(this.resolvedDataSources, "DataSource router not initialized");
  Object lookupKey = determineCurrentLookupKey();
  DataSource dataSource = this.resolvedDataSources.get(lookupKey);
  if (dataSource == null && (this.lenientFallback || lookupKey == null)) {
   dataSource = this.resolvedDefaultDataSource;
  }
  if (dataSource == null) {
   throw new IllegalStateException("Cannot determine target DataSource for lookup key [" + lookupKey + "]");
  }
  return dataSource;
 }

 /**
  * Determine the current lookup key. This will typically be
  * implemented to check a thread-bound transaction context.
  * 
Allows for arbitrary keys. The returned key needs
  * to match the stored lookup key type, as resolved by the
  * {@link #resolveSpecifiedLookupKey} method.
  */
 protected abstract Object determineCurrentLookupKey();
　　
　　.............

}

在动态切换数据源方法时选择了AOP方式实现，这里实现的简单粗暴，具体应用时根据实际需要灵活变通吧 

题外话，这里提下SqlServer驱动选择的问题，目前SqlServer的驱动主要有微软的官方驱动和JTDS驱动两种，关于这两个驱动我做过测试，批量更新，在小数据量(100以下)时，JTDS相对微软驱动性能稍微高一点点，在数据量增大时几万到上百万时，微软驱动有着明显优势，所以若对性能比较敏感，建议使用微软驱动，否则随意

微软驱动在Maven库找不到，这点比较郁闷，若使用maven的话还得先安装到本地，这点很不爽

JTDS使用比较方便Maven直接引用即可

相关jar maven引用

  UTF-8
  3.2.7.RELEASE
 

 
  
   org.aspectj
   aspectjweaver
   1.7.2
  
  
   commons-dbcp
   commons-dbcp
   1.4
  
  
   commons-logging
   commons-logging
   1.1.3
  
  
   log4j
   log4j
   1.2.17
  
  
   org.springframework
   spring-core
   ${org.springframework.version}
  
  
   org.springframework
   spring-beans
   ${org.springframework.version}
  
  
   org.springframework
   spring-aop
   ${org.springframework.version}
  
  
   org.springframework
   spring-context
   ${org.springframework.version}
  
  
   org.springframework
   spring-jdbc
   ${org.springframework.version}
  
  
   org.springframework
   spring-context-support
   ${org.springframework.version}
  
  
   org.springframework
   spring-web
   ${org.springframework.version}
  
  
   org.springframework
   spring-webmvc
   ${org.springframework.version}
  
  
   org.springframework
   spring-tx
   ${org.springframework.version}
  
  
   org.mybatis
   mybatis
   3.2.4
  
  
   org.mybatis
   mybatis-spring
   1.2.2
  
  
   org.slf4j
   slf4j-log4j12
   1.7.6
  
  
   net.sourceforge.jtds
   jtds
   1.2.8
  
  
   mysql
   mysql-connector-java
   5.1.29
  
 

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持脚本之家。