IT忍者神龟之Spring+MyBatis多数据源配置实现 / 憋错料

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

log4j.properties

#============================================================================

# 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

jdbc.properties

单数据源时的Spring配置文件

<?xml
version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xmlns:context="http://www.springframework.org/schema/context"

xmlns:aop="http://www.springframework.org/schema/aop"

xsi:schemaLocation="http://www.springframework.org/schema/beans

http://www.springframework.org/schema/beans/spring-beans-3.0.xsd

http://www.springframework.org/schema/context

http://www.springframework.org/schema/context/spring-context-3.0.xsd

http://www.springframework.org/schema/aop

http://www.springframework.org/schema/aop/spring-aop-3.0.xsd">

</bean>

</bean>

</bean>

</bean>

<context:component-scan base-package="com.cnblogs.lzrabbit"/>

<aop:aspectj-autoproxy/>

</beans>

多数据源时Spring配置文件

<?xml
version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xmlns:context="http://www.springframework.org/schema/context"

xmlns:aop="http://www.springframework.org/schema/aop"

xsi:schemaLocation="http://www.springframework.org/schema/beans

http://www.springframework.org/schema/beans/spring-beans-3.0.xsd

http://www.springframework.org/schema/context

http://www.springframework.org/schema/context/spring-context-3.0.xsd

http://www.springframework.org/schema/aop

http://www.springframework.org/schema/aop/spring-aop-3.0.xsd">

</bean>

</bean>

</bean>

<map>

</map>

</property>

</bean>

</bean>

</bean>

<context:component-scan base-package="com.cnblogs.lzrabbit"/>

<aop:aspectj-autoproxy/>

</beans>

applicationContext.xml

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<String> dataSourceKey = new InheritableThreadLocal<String>();

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<Map<String,Object>> getList();

}

public interface SqlServerMapper {

@Select("select * from MyTable")

List<Map<String,Object>> getList();

}

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();

}

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();
    }
}

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, [email protected], 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: 8
2014-05-25 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

<bean id="multipleDataSource" class="com.cnblogs.lzrabbit.MultipleDataSource">
        <property name="defaultTargetDataSource" ref="mySqlDataSource"/>
        <property name="targetDataSources">
            <map>
                <entry key="mySqlDataSource" value-ref="mySqlDataSource"/>
                <entry key="sqlServerDataSource" value-ref="sqlServerDataSource"/>
            </map>
        </property>
    </bean>

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<Object, Object> 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.
     * <p>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

IT忍者神龟之Spring+MyBatis多数据源配置实现

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