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%nlog4j.rootLogger=DEBUG,Consolelog4j.logger.com.cnblogs.lzrabbit=DEBUGlog4j.logger.org.springframework=ERRORlog4j.logger.org.mybatis=ERRORlog4j.logger.org.apache.ibatis=ERRORlog4j.logger.org.quartz=ERRORlog4j.logger.org.apache.axis2=ERRORlog4j.logger.org.apache.axiom=ERRORlog4j.logger.org.apache=ERRORlog4j.logger.httpclient=ERROR#log4j.additivity.org.springframework=false#Console log4j.appender.Console=org.apache.log4j.ConsoleAppenderlog4j.appender.Console.Threshold=DEBUG  log4j.appender.Console.Target=System.out  log4j.appender.Console.layout=org.apache.log4j.PatternLayout  log4j.appender.Console.layout.ConversionPattern=${ConversionPattern}#log4j.appender.Console.encoding=UTF-8#org.apache.log4j.DailyRollingFileAppenderlog4j.appender.DailyFile=org.apache.log4j.DailyRollingFileAppenderlog4j.appender.DailyFile.DatePattern='.'yyyy-MM-dd'.log'log4j.appender.DailyFile.File=${myApp.root}/logs/daily.loglog4j.appender.DailyFile.Append=truelog4j.appender.DailyFile.Threshold=DEBUGlog4j.appender.DailyFile.layout=org.apache.log4j.PatternLayoutlog4j.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.Driverjdbc.mysql.url=jdbc:mysql://127.0.0.1:3306/test?useUnicode=true&characterEncoding=UTF-8&allowMultiQueries=truejdbc.mysql.username=rootjdbc.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.Driverjdbc.sqlserver.url=jdbc:jtds:sqlserver://127.0.0.1:1433/testjdbc.sqlserver.username=sajdbc.sqlserver.password=sa#============================================================================# 通用配置#============================================================================jdbc.initialSize=5jdbc.minIdle=5jdbc.maxIdle=20jdbc.maxActive=100jdbc.maxWait=100000jdbc.defaultAutoCommit=falsejdbc.removeAbandoned=truejdbc.removeAbandonedTimeout=600jdbc.testWhileIdle=truejdbc.timeBetweenEvictionRunsMillis=60000jdbc.numTestsPerEvictionRun=20jdbc.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

按 Ctrl+C 复制代码

按 Ctrl+C 复制代码

MyBatis接口Mapper定义，直接使用注解方式实现

public interface MySqlMapper {    @Select("select * from MyTable")    List

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@Aspectpublic 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.cnblogs.lzrabbit.MySqlMapper.getList - ooo Using Connection [jdbc:mysql://127.0.0.1:3306/test?useUnicode=true&characterEncoding=UTF-8&allowMultiQueries=true, UserName=root@192.168.1.32, MySQL Connector Java]2014-05-25 20:02:04,333 DEBUG [main] com.cnblogs.lzrabbit.MySqlMapper.getList - ==>  Preparing: select * from MyTable 2014-05-25 20:02:04,371 DEBUG [main] com.cnblogs.lzrabbit.MySqlMapper.getList - ==> Parameters: 2014-05-25 20:02:04,396 DEBUG [main] com.cnblogs.lzrabbit.MySqlMapper.getList - <==      Total: 82014-05-25 20:02:04,620 DEBUG [main] com.cnblogs.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.cnblogs.lzrabbit.SqlServerMapper.getList - ==>  Preparing: select * from TmallCityMap 2014-05-25 20:02:04,621 DEBUG [main] com.cnblogs.lzrabbit.SqlServerMapper.getList - ==> Parameters: 2014-05-25 20:02:04,681 DEBUG [main] com.cnblogs.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
                  
             
        

 

 

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