Spring實現數據庫讀寫分離/spring事務配置解釋(Annotation/Spring AOP/Reflection)

項目開發中讀寫的頻率差距很大，所以實現讀寫分離：主庫(master)中非實時讀取的查詢交給負載均衡的從庫(slave)，查詢cpu的消耗和寫入的io延時，保證DB系統的健壯性。

最終問題，分佈式事務的線索。最後附源碼[springmvc+spring+mybatis+MySQL]：

注：註釋和部分代碼省略。
1：AbstractRoutingDataSource這個數據源路由類是spring2.0以後增加的，AbstractRoutingDataSource的定義：
 /* @since 2.0.1*/
public abstract class AbstractRoutingDataSource extends AbstractDataSource implements InitializingBean {……}
通過實現determineCurrentLookupKey()抽象方法可以實現讀寫數據源的切換。
2：AbstractRoutingDataSource繼承了AbstractDataSource，而AbstractDataSource是DataSource的子類。DataSource是javax.sql的數據源接口，定義：
public interface DataSource  extends CommonDataSource,Wrapper {
  Connection getConnection() throws SQLException;
  Connection getConnection(String username, String password) throws SQLException;
}
DataSource數據源接口定義了2個方法，都是獲取數據庫連接的。
3：AbstractRoutingDataSource這個數據源路由類對獲取連接的實現：
public abstract class AbstractRoutingDataSource extends AbstractDataSource implements InitializingBean {
	private Map<Object, DataSource> resolvedDataSources;
	private Object defaultTargetDataSource;
	private Map<Object, Object> targetDataSources;
	
	@Override
	public Connection getConnection() throws SQLException {
		return determineTargetDataSource().getConnection();
	}

	@Override
	public Connection getConnection(String username, String password) throws SQLException {
		return determineTargetDataSource().getConnection(username, password);
	}
	
	protected abstract Object determineCurrentLookupKey();
}
通過自己定義的determineTargetDataSource()方法獲取到數據連接connection。
4：determineTargetDataSource的定義：
	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;
	}
determineCurrentLookupKey方法返回lookupKey,resolvedDataSources方法就是根據lookupKey從Map中獲得數據源。從3看出resolvedDataSources集合屬性和determineCurrentLookupKey()抽象方法定義。
5：我們自己定義類繼承路由類AbstractRoutingDataSource去實現determineCurrentLookupKey()方法，然後自己來切換字符串告訴this.resolvedDataSources.get(lookupKey);方法這個lookupKey是誰？(也就是這個字符所對應的數據源的key(請看mybatis-context.xml配置40行注入defaultTargetDataSource和targetDataSources的值,通過‘lookupKey’字符串切換，spring注入的數據源對象.

1：通過註解在dao方法上註解，此方法開啓那個數據源：

package com.common.readwriteseparate;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface DataSource {
    String value();
}

2：自己定義類繼承路由類去實現determineCurrentLookupKey()方法：

package com.common.readwriteseparate;

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

public class DynamicDataSource extends AbstractRoutingDataSource{
	
    @Override
    protected Object determineCurrentLookupKey() {
    	String dataSouceKey = DynamicDataSourceHolder.getDataSouce();
    	return dataSouceKey;
    }
    
}

多線程輔助類：

package com.common.readwriteseparate;

public class DynamicDataSourceHolder {
    
	public static final ThreadLocal<String> holder = new ThreadLocal<String>();

    public static void putDataSource(String name) {
        holder.set(name);
    }

    public static String getDataSouce() {
        return holder.get();
    }
}

在DynamicDataSource的定義知道，返回的是DynamicDataSourceHolder.getDataSouce()值，我們需要在程序運行時調用DynamicDataSourceHolder.putDataSource()方法，對dataSouceKey數據源key賦值。

3：通過Spring AOP/Reflection獲取執行獲取註解的value然後DynamicDataSourceHolder.putDataSource(value)告訴要使用那個數據源：

package com.common.readwriteseparate;

import java.lang.reflect.Method;

import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.reflect.MethodSignature;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class DataSourceAspect {
    //log 
    private static final Logger LOG = LoggerFactory.getLogger(DataSourceAspect.class);

    public void before(JoinPoint point) {
        Object target = point.getTarget();
        String method = point.getSignature().getName();
        Class<?>[] classz = target.getClass().getInterfaces();
        Class<?>[] parameterTypes = ((MethodSignature) point.getSignature()).getMethod().getParameterTypes();
        try {
            Method methodRefRes = classz[0].getMethod(method, parameterTypes);
            if (methodRefRes != null && methodRefRes.isAnnotationPresent(DataSource.class)) {
                DataSource data = methodRefRes.getAnnotation(DataSource.class);
                DynamicDataSourceHolder.putDataSource(data.value());
                LOG.info("\n************************************************\n" + "\t~~~DB:: " + data.value() + "\n************************************************");
            }
        } catch (Exception e) {
        	LOG.error("數據源失敗切面獲取異常:" + e.getMessage(), e);
        }
    }
}

5：先看看配置：

①spring的配置(spring-context.xml)：

<?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:p="http://www.springframework.org/schema/p"  
    xmlns:context="http://www.springframework.org/schema/context"  
    xmlns:aop="http://www.springframework.org/schema/aop"
    xmlns:mvc="http://www.springframework.org/schema/mvc"  
    xsi:schemaLocation="http://www.springframework.org/schema/beans    
                        http://www.springframework.org/schema/beans/spring-beans-3.2.xsd    
                        http://www.springframework.org/schema/context    
                        http://www.springframework.org/schema/context/spring-context-3.2.xsd
                        http://www.springframework.org/schema/aop 
            			http://www.springframework.org/schema/aop/spring-aop-3.2.xsd    
                        http://www.springframework.org/schema/mvc    
                        http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd">  
                        
	<!-- 使用annotation 自動註冊bean,並檢查@Required,@Autowired的屬性已被注入 -->
	<context:component-scan base-package="com.user.service,com.user.dao,com.user.bean,com.user.xml" />
	
	<!-- 引入屬性配置文件 -->
 	<bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"> 
		<property name="location" value="classpath:database.properties" />        
	</bean>  
	
	<!--或 <context:property-placeholder location="classpath*:*.properties" /> -->
</beans>

②：mybatis-context.xml的配置：

<?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:mvc="http://www.springframework.org/schema/mvc" 
	xmlns:tx="http://www.springframework.org/schema/tx"
	xmlns:aop="http://www.springframework.org/schema/aop" 
	xsi:schemaLocation="http://www.springframework.org/schema/mvc 
	http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd
	http://www.springframework.org/schema/beans 
	http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
	http://www.springframework.org/schema/context 
	http://www.springframework.org/schema/context/spring-context-4.0.xsd
	http://www.springframework.org/schema/tx 
	http://www.springframework.org/schema/tx/spring-tx-4.0.xsd
	http://www.springframework.org/schema/aop 
	http://www.springframework.org/schema/aop/spring-aop-4.0.xsd" default-lazy-init="true">
	<description>MyBatis的數據庫持久層配置/配置主-從數據源</description>
	<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
		<property name="dataSource" ref="dataSource" />
		<!-- 自動掃描entity目錄, 省掉Configuration.xml裏的手工配置 -->
		<property name="mapperLocations" value="classpath*:com/user/xml/*.xml" />
		<property name="configLocation" value="classpath:mybatis-config.xml"></property>
	</bean>
	<!-- 掃描dao -->
	<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
		<property name="basePackage" value="com.user.dao" />
		<property name="sqlSessionFactoryBeanName" value="sqlSessionFactory" />
	</bean>
	<!-- 配置數據庫註解aop -->
	<aop:aspectj-autoproxy />
	<bean id="dataSourceAspect" class="com.common.readwriteseparate.DataSourceAspect" />
	<aop:config>
		<aop:aspect id="c" ref="dataSourceAspect">
			<aop:pointcut id="tx" expression="execution(* com.user.dao.*.*(..))" />
			<aop:before pointcut-ref="tx" method="before" />
		</aop:aspect>
	</aop:config>
	<!-- 主-從數據源路由 -->
	<bean id="dataSource" class="com.common.readwriteseparate.DynamicDataSource">
        <property name="targetDataSources">  
              <map key-type="java.lang.String">  
                  <!-- write -->
                 <entry key="master" value-ref="masterDataSource"/>  
                 <!-- read -->
                 <entry key="slave" value-ref="slaveDataSource"/>  
              </map>  
        </property>  
        <property name="defaultTargetDataSource" ref="masterDataSource"/>  
    </bean>
</beans>

③：mybatis-config.xml：

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd">  
<configuration>  
    <typeAliases>
  	   <package name="com.user.bean"/>
 	</typeAliases>
</configuration>

④：database.properties：

#mysql-Used to verify the effectiveness of the database connection 
validationQuery=SELECT 1
jdbc.initialSize=5
jdbc.maxActive=20
jdbc.maxWait=60000
jdbc.poolPreparedStatements=false
jdbc.poolMaximumIdleConnections=0
jdbc.driverClassName=org.gjt.mm.mysql.Driver
#1.tms business.  2.The db level optimization,data concurrency,desirable.
master.jdbc.url=jdbc:mysql://your ip:3306/master?useUnicode=true&characterEncoding=UTF-8&zeroDateTimeBehavior=convertToNull
slave.jdbc.url=jdbc:mysql://your ip:3306/slave?useUnicode=true&characterEncoding=UTF-8&zeroDateTimeBehavior=convertToNull
jdbc.username=username
jdbc.password=password

⑤：數據源配置：datasource-context.xml：

<?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:mvc="http://www.springframework.org/schema/mvc" xmlns:tx="http://www.springframework.org/schema/tx"
	xmlns:aop="http://www.springframework.org/schema/aop"
	xsi:schemaLocation="http://www.springframework.org/schema/mvc 
	http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd
	http://www.springframework.org/schema/beans 
	http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
	http://www.springframework.org/schema/context 
	http://www.springframework.org/schema/context/spring-context-4.0.xsd
	http://www.springframework.org/schema/tx 
	http://www.springframework.org/schema/tx/spring-tx-4.0.xsd
	http://www.springframework.org/schema/aop 
	http://www.springframework.org/schema/aop/spring-aop-4.0.xsd" default-lazy-init="true">
	<description>配置主-從數據源</description>
	<!-- 配置數據源-Master -->
	<bean name="masterDataSource" class="com.alibaba.druid.pool.DruidDataSource" init-method="init" destroy-method="close">
		<property name="driverClassName" value="${jdbc.driverClassName}" />
		<property name="url" value="${master.jdbc.url}" />
		<property name="username" value="${jdbc.username}" />
		<property name="password" value="${jdbc.password}" />
		<!-- 初始化連接大小 -->
		<property name="initialSize" value="0" />
		<!-- 連接池最大使用連接數量 -->
		<property name="maxActive" value="20" />
		<!-- 連接池最大空閒 error:maxIdle is deprecated -->
		<!-- <property name="maxIdle" value="20" /> -->
		<!-- 連接池最小空閒 -->
		<property name="minIdle" value="0" />
		<!-- 獲取連接最大等待時間 -->
		<property name="maxWait" value="60000" />
		<!-- <property name="poolPreparedStatements" value="true" /> <property name="maxPoolPreparedStatementPerConnectionSize" value="33" /> -->
		<property name="validationQuery" value="${validationQuery}" />
		<property name="testOnBorrow" value="false" />
		<property name="testOnReturn" value="false" />
		<property name="testWhileIdle" value="true" />
		<!-- 配置間隔多久才進行一次檢測，檢測需要關閉的空閒連接，單位是毫秒 -->
		<property name="timeBetweenEvictionRunsMillis" value="60000" />
		<!-- 配置一個連接在池中最小生存的時間，單位是毫秒 -->
		<property name="minEvictableIdleTimeMillis" value="25200000" />
		<!-- 打開removeAbandoned功能 -->
		<property name="removeAbandoned" value="true" />
		<!-- 1800秒，也就是30分鐘 -->
		<property name="removeAbandonedTimeout" value="1800" />
		<!-- 關閉abanded連接時輸出錯誤日誌 -->
		<property name="logAbandoned" value="true" />
		<!-- 監控數據庫 -->
		<!-- <property name="filters" value="stat" /> -->
		<property name="filters" value="mergeStat" />
	</bean>
	<!-- 配置數據源-Slave -->
	<bean name="slaveDataSource" class="com.alibaba.druid.pool.DruidDataSource" init-method="init" destroy-method="close">
		<property name="driverClassName" value="${jdbc.driverClassName}" />
		<property name="url" value="${slave.jdbc.url}" />
		<property name="username" value="${jdbc.username}" />
		<property name="password" value="${jdbc.password}" />
		<!-- 初始化連接大小 -->
		<property name="initialSize" value="0" />
		<!-- 連接池最大使用連接數量 -->
		<property name="maxActive" value="20" />
		<!-- 連接池最大空閒 error:maxIdle is deprecated -->
		<!-- <property name="maxIdle" value="20" /> -->
		<!-- 連接池最小空閒 -->
		<property name="minIdle" value="0" />
		<!-- 獲取連接最大等待時間 -->
		<property name="maxWait" value="60000" />
		<!-- <property name="poolPreparedStatements" value="true" /> <property name="maxPoolPreparedStatementPerConnectionSize" value="33" /> -->
		<property name="validationQuery" value="${validationQuery}" />
		<property name="testOnBorrow" value="false" />
		<property name="testOnReturn" value="false" />
		<property name="testWhileIdle" value="true" />
		<!-- 配置間隔多久才進行一次檢測，檢測需要關閉的空閒連接，單位是毫秒 -->
		<property name="timeBetweenEvictionRunsMillis" value="60000" />
		<!-- 配置一個連接在池中最小生存的時間，單位是毫秒 -->
		<property name="minEvictableIdleTimeMillis" value="25200000" />
		<!-- 打開removeAbandoned功能 -->
		<property name="removeAbandoned" value="true" />
		<!-- 1800秒，也就是30分鐘 -->
		<property name="removeAbandonedTimeout" value="1800" />
		<!-- 關閉abanded連接時輸出錯誤日誌 -->
		<property name="logAbandoned" value="true" />
		<!-- 監控數據庫 -->
		<!-- <property name="filters" value="stat" /> -->
		<property name="filters" value="mergeStat" />
	</bean>
</beans>

⑥transaction-context.xml事務配置：

<?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:mvc="http://www.springframework.org/schema/mvc" xmlns:tx="http://www.springframework.org/schema/tx"
	xmlns:aop="http://www.springframework.org/schema/aop"
	xsi:schemaLocation="http://www.springframework.org/schema/mvc 
	http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd
	http://www.springframework.org/schema/beans 
	http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
	http://www.springframework.org/schema/context 
	http://www.springframework.org/schema/context/spring-context-4.0.xsd
	http://www.springframework.org/schema/tx 
	http://www.springframework.org/schema/tx/spring-tx-4.0.xsd
	http://www.springframework.org/schema/aop 
	http://www.springframework.org/schema/aop/spring-aop-4.0.xsd" default-lazy-init="true">
	<description>配置事物</description>
	<!-- 註解方式配置事物 -->
	<tx:annotation-driven transaction-manager="transactionManager" />
	<!-- 配置事務管理器 -->
	<bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
		<property name="dataSource" ref="dataSource" />
	</bean>
	<aop:config>
		<aop:pointcut expression="(execution(* com.user.service.*.* (..)))" id="pointcut" />
		<aop:advisor advice-ref="txAdvice" pointcut-ref="pointcut" />
	</aop:config>
	<!-- 事務控制 -->
	<tx:advice id="txAdvice" transaction-manager="transactionManager">
		<tx:attributes>
			<tx:method name="load*" read-only="true" />
			<tx:method name="get*" read-only="true" />
			<tx:method name="create*" propagation="REQUIRED" rollback-for="java.lang.Exception" />
			<tx:method name="save*" propagation="REQUIRED" rollback-for="java.lang.Exception" />
			<tx:method name="update*" propagation="REQUIRED" rollback-for="java.lang.Exception" />
			<tx:method name="insert*" propagation="REQUIRED" rollback-for="java.lang.Exception" />
			<tx:method name="delete*" propagation="REQUIRED" rollback-for="java.lang.Exception" />
			<tx:method name="schedule*" propagation="REQUIRED" rollback-for="java.lang.Exception" />
			<tx:method name="do*" propagation="REQUIRED" rollback-for="java.lang.Exception" />
			
			<!-- 一個事務涉及一個數據源不能在事務內部去切換數據源成功，所以對多數據源的方法暫不開啓事務~分佈式事務 -->
			<!-- <tx:method name="crud*" propagation="REQUIRED" rollback-for="java.lang.Exception" /> -->
			<!-- <tx:method name="*" /> -->
		</tx:attributes>
	</tx:advice>
</beans>

⑦：log4j.properties日誌配置:

# Set root category priority to INFO and its only appender to CONSOLE.
log4j.rootLogger=info, STDOUT, FILEOUT
# CONSOLE is set to be a ConsoleAppender using a PatternLayout.
log4j.appender.STDOUT=org.apache.log4j.ConsoleAppender
log4j.appender.STDOUT.encoding=UTF-8
log4j.appender.STDOUT.layout=org.apache.log4j.PatternLayout
log4j.appender.STDOUT.layout.ConversionPattern=%-d{yyyy-MM-dd HH:mm:ss}  [ %t:%r ] - [ %p ]  %m %n

# FILEOUT is set to be a File appender using a PatternLayout.
log4j.appender.FILEOUT=org.apache.log4j.RollingFileAppender
#tomcat1
#log4j.appender.FILEOUT.File=/home/logs/timespacexstar1/timespacexstar.log
#tomcat2
log4j.appender.FILEOUT.File=/home/logs/mydemoweb/mydemoweb.log
log4j.appender.FILEOUT.MaxFileSize=5MB
log4j.appender.FILEOUT.MaxBackupIndex=10
log4j.appender.FILEOUT.encoding=UTF-8
log4j.appender.FILEOUT.layout=org.apache.log4j.PatternLayout
log4j.appender.FILEOUT.layout.ConversionPattern=%-d{yyyy-MM-dd HH:mm:ss}  [ %t:%r ] - [ %p ]  %m %n
# SQL
log4j.logger.java.sql.ResultSet=debug
log4j.logger.org.apache=debug
log4j.logger.java.sql.Connection=debug
log4j.logger.java.sql.Statement=debug
log4j.logger.java.sql.PreparedStatement=debug

6：代碼實現：

①：dao層：

package com.user.dao;

import com.common.readwriteseparate.DataSource;
import com.user.bean.Member;

public interface MemberMapper {
	
	@DataSource("master")
    int deleteByPrimaryKey(Integer id);
	@DataSource("master")
    int insert(Member record);
	@DataSource("master")
    int insertSelective(Member record);
    @DataSource("master")
    int updateByPrimaryKeySelective(Member record);
    @DataSource("master")
    int updateByPrimaryKey(Member record);

    @DataSource("slave")
    Member selectByPrimaryKey(Integer id);
}

②：業務層代碼：

package com.user.service;

import com.user.bean.Member;


public interface MemberService {

	Member crudMember(Member member);
}

實現：

package com.user.service.impl;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.interceptor.TransactionAspectSupport;

import com.user.bean.Member;
import com.user.dao.MemberMapper;
import com.user.service.MemberService;


@Service("memberService")
public class MemberServiceImpl implements MemberService {
	
	//log 
    private static final Logger LOG = LoggerFactory.getLogger(MemberServiceImpl.class);
    
    @Autowired
    private MemberMapper memeberDao;
		@Override
	public Member crudMember(Member member) {
		Member resMember = null;
		try {
			resMember = memeberDao.selectByPrimaryKey(member.getId());
			LOG.info(member.getId() + "查詢成功~");
			memeberDao.insert(member);
			LOG.info(member.getUsername() + "註冊成功~");
		} catch (Exception e) {
			LOG.error("用戶id："+member.getId()+"保存和查詢失敗~~~" + e.getMessage(), e);
			TransactionAspectSupport.currentTransactionStatus().setRollbackOnly();
		}
		return resMember;
	}

}

③：master數據庫沒有id爲2的member註冊，但slave中有一個用戶，先查詢從庫用戶，再插入主庫這個member，不涉及業務僅對分庫測試：

junit測試代碼：

package com.user.test;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

import com.common.definition.DictionaryDefinition;
import com.user.bean.Member;
import com.user.service.MemberService;

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = {"classpath:spring-context.xml","classpath:datasource-context.xml",
		"classpath:mybatis-context.xml","classpath:transaction-context.xml"})
public class UserTest {
	  //log 
    private static final Logger LOG = LoggerFactory.getLogger(UserTest.class);
    
    @Autowired
    private MemberService memberService;

    /**
     * 主從分離測試，非支持事務
     * */
    @Test
    public void crudTraM(){
	    Member member = new Member();
	    member.setId(2);
	    member.setUsername("Tony5");
	    member.setPassword("12345678");
	    member.setStatus(DictionaryDefinition.LOGIN_NORMAL);
	  
	    Member member1 = memberService.crudMember(member);
	    if(member1 != null){
		  LOG.info("結果~~：" + member1.getUsername());
	    }else{
	    	 LOG.info("主從事物回滾測試失敗數據爲空");
	    }
    }
}

效果：master插入前：

後：

slave前後不變：

junit代碼測試結果log：

2016-04-11 18:48:32  [ main:2195 ] - [ INFO ]  
************************************************
	~~~DB:: slave
************************************************ 
2016-04-11 18:48:32  [ main:2879 ] - [ INFO ]  2查詢成功~ 
2016-04-11 18:48:32  [ main:2880 ] - [ INFO ]  
************************************************
	~~~DB:: master
************************************************ 
2016-04-11 18:48:32  [ main:2977 ] - [ INFO ]  Tony5註冊成功~ 
2016-04-11 18:48:32  [ main:2977 ] - [ INFO ]  結果~~：kekeai

上邊完成了在service層同一方法中數據源的切換，但這個方法必須不支持事務，不然切換失敗！！！

A:spring事務的默然配置：

<tx:method name="*" />

默認意義：

①：事務傳播設置是 REQUIRED
②：隔離級別是數據庫 DEFAULT
③：事務是支持讀/寫
④：事務超時默認是依賴於事務系統的，或者事務超時沒有被支持。
⑤：任何 RuntimeException 將觸發事務回滾，但是任何 checked Exception 將不觸發事務回滾

<tx:method/> 有關事務自定義的設置：

源代碼：Spring實現數據庫讀寫分離

數據庫sql：db_rw_separate.sql

附錄：

web.xml:

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns="http://java.sun.com/xml/ns/javaee"
	xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
	version="3.0">
	<display-name>Archetype Created Web Application</display-name>
	<!-- Spring監聽器 -->
	<listener>
		<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
	</listener>
	<context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>classpath*:*-context.xml</param-value>
    </context-param>
	<!-- 編碼utf-8 -->
	<filter>
		<filter-name>charFilter</filter-name>
		<filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
		<init-param>
			<param-name>encoding</param-name>
			<param-value>UTF-8</param-value>
		</init-param>
	</filter>
	<filter-mapping>
		<filter-name>charFilter</filter-name>
		<url-pattern>/*</url-pattern>
	</filter-mapping>
	<servlet>
		<servlet-name>springMvc</servlet-name>
		<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
		<init-param>
			<param-name>contextConfigLocation</param-name>
			<param-value>classpath:spring-mvc.xml</param-value>
		</init-param>
	</servlet>
	<servlet-mapping>
		<servlet-name>springMvc</servlet-name>
		<url-pattern>/</url-pattern>
	</servlet-mapping>
	
	<welcome-file-list>
		<welcome-file>/index.jsp</welcome-file>
	</welcome-file-list>
	<!-- 配置SESSION超時，單位是分鐘 -->
	<session-config>
		<session-timeout>45</session-timeout>
	</session-config>

</web-app>

spring-mvc.xml:

<?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:p="http://www.springframework.org/schema/p"  
    xmlns:context="http://www.springframework.org/schema/context"  
    xmlns:mvc="http://www.springframework.org/schema/mvc"  
    xsi:schemaLocation="http://www.springframework.org/schema/beans    
                        http://www.springframework.org/schema/beans/spring-beans-3.1.xsd    
                        http://www.springframework.org/schema/context    
                        http://www.springframework.org/schema/context/spring-context-3.1.xsd    
                        http://www.springframework.org/schema/mvc    
                        http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd">  
    <!-- 自動掃描該包，使SpringMVC認爲包下用了@controller註解的類是控制器 -->  
    <context:component-scan base-package="com.ourtimes.controller" />  
    <!--避免IE執行AJAX時，返回JSON出現下載文件 -->  
    <bean id="mappingJacksonHttpMessageConverter"  
        class="org.springframework.http.converter.json.MappingJacksonHttpMessageConverter">  
        <property name="supportedMediaTypes">  
            <list>  
                <value>text/html;charset=UTF-8</value>  
            </list>  
        </property>  
    </bean>  
    <!-- 啓動SpringMVC的註解功能，完成請求和註解POJO的映射 -->  
    <bean  
        class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter">  
        <property name="messageConverters">  
            <list>  
                <ref bean="mappingJacksonHttpMessageConverter" /> <!-- JSON轉換器 -->  
            </list>  
        </property>  
    </bean>  
    <!-- 定義跳轉的文件的前後綴 ，視圖模式配置-->  
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">  
        <!-- 這裏的配置我的理解是自動給後面action的方法return的字符串加上前綴和後綴，變成一個 可用的url地址 -->  
        <property name="prefix" value="/WEB-INF/views/" />  
        <property name="suffix" value=".jsp" />  
    </bean>  
      
    <!-- 配置文件上傳，如果沒有使用文件上傳可以不用配置，當然如果不配，那麼配置文件中也不必引入上傳組件包 -->  
    <bean id="multipartResolver"    
        class="org.springframework.web.multipart.commons.CommonsMultipartResolver">    
        <!-- 默認編碼 -->  
        <property name="defaultEncoding" value="utf-8" />    
        <!-- 文件大小最大值 -->  
        <property name="maxUploadSize" value="10485760000" />    
        <!-- 內存中的最大值 -->  
        <property name="maxInMemorySize" value="40960" />    
    </bean>   
  
</beans>

TS_A1

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