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使用Spring解決ibatis多數據源的苦惱

←手機掃碼閱讀     火星人 @ 2014-03-09 , reply:0

iBatis多數據源的苦惱

在僅使用ibatis時,多數據源簡直就是夢魘,每多一個數據源就需要多一份sql-map-config配置文件.

採用spring的AbstractRoutingDataSource就可以簡單的解決這個問題.

AbstractRoutingDataSource實現了javax.sql.DataSource介面,因此可以理解為一個虛擬的動態DataSource,在需要的時候根據上下文Context動態決定使用哪個數據源.

Spring iBatis多數據源的配置

下面是一個完整的配置:

< beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:aop="http://www.springframework.org/schema/aop"
xmlns:tx="http://www.springframework.org/schema/tx"
xmlns:jee="http://www.springframework.org/schema/jee"
xsi:schemaLocation="
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.5.xsd
http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.5.xsd
http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-2.5.xsd">


< !-- ========================= GENERAL DEFINITIONS ========================= -->
< jee:jndi-lookup id="ds0" jndi-name="jdbc/ds0"/>
< jee:jndi-lookup id="ds1" jndi-name="jdbc/ds1"/>
< jee:jndi-lookup id="ds2" jndi-name="jdbc/ds2"/>

< bean id="dataSource" class="com.xxx.xxx.util.DynamicDataSource">
< property name="targetDataSources">
< map key-type="java.lang.String">
< entry key="0" value-ref="ds0"/>
< entry key="1" value-ref="ds1"/>
< entry key="2" value-ref="ds2"/>
< /map>
< /property>
< property name="defaultTargetDataSource" ref="1"/>
< /bean>
< !-- SqlMap setup for iBATIS Database Layer -->
< bean id="sqlMapClient" class="org.springframework.orm.ibatis.SqlMapClientFactoryBean">
< property name="dataSource" ref="dataSource"/>
< property name="configLocation" value="classpath:com/xxx/xxx/dao/sqlmap/sql-map-config.xml"/>
< /bean>
< bean id="testDAO" class="com.xxx.xxx.dao.impl.TestDAO">
< property name="sqlMapClient" ref="sqlMapClient"/>
< /bean>
< bean id="testService" class="com.xxx.xxx.service.impl.TestService">
< property name="testDAO" ref="testDAO"/>
< /bean>
< /beans>

其核心是DynamicDataSource,代碼如下

package com.xxx.xxx.util;

import org.apache.log4j.Logger;
import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;

public class DynamicDataSource extends AbstractRoutingDataSource {

static Logger log = Logger.getLogger("DynamicDataSource");
@Override
protected Object determineCurrentLookupKey() {
// TODO Auto-generated method stub
return DbContextHolder.getDbType();
}

}

上下文DbContextHolder為一線程安全的ThreadLocal,如下

package com.xxx.xxx.util;

public class DbContextHolder {
private static final ThreadLocal contextHolder = new ThreadLocal();

public static void setDbType(String dbType) {
contextHolder.set(dbType);
}

public static String getDbType() {
return (String) contextHolder.get();
}

public static void clearDbType() {
contextHolder.remove();
}
}

sql-map-config.xml如下

< ?xml version="1.0" encoding="UTF-8" standalone="no"?>
< !DOCTYPE sqlMapConfig PUBLIC "-//iBATIS.com//DTD SQL Map Config 2.0//EN"
"http://www.ibatis.com/dtd/sql-map-config-2.dtd">

< sqlMapConfig>

< sqlMap resource="com/xxx/xxx/dao/sqlmap/Object.xml"/>

< /sqlMapConfig>

這樣在調用service之前只需要設置一下上下文即可調用相應的數據源,如下:

DbContextHolder.setDbType("2");
//execute services
//.........

dao如下

package com.xxx.xxx.dao.impl;

import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.apache.log4j.Logger;
import org.springframework.orm.ibatis.support.SqlMapClientDaoSupport;

import com.xxx.xxx.vo.TestObj;

public class TestDAO extends SqlMapClientDaoSupport implements ITestDAO {

static Logger log = Logger.getLogger(TestDAO.class);

public TestObj getTestObj(String objID) throws Exception {
return (TestObj) getSqlMapClientTemplate().queryForObject("getTestObj", objID);
}
}

以上就介紹了Spring iBatis多數據源的配置方案.本文來自eddysheng的博客:《基於spring和ibatis的多數據源切換方案》.


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