使用AOP 实现多数据源 切换

多数据源的实现，这里就来个实例吧

1、在 spring 的配置文件中数据源信息

<?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:util="http://www.springframework.org/schema/util"
	xmlns:tx="http://www.springframework.org/schema/tx" xmlns:aop="http://www.springframework.org/schema/aop"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.1.xsd
        http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-4.1.xsd
        http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-4.1.xsd
        http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.1.xsd 
        http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.1.xsd">

	<!-- 加载配置属性文件 -->
	<context:property-placeholder
		ignore-unresolvable="true" location="classpath:conf.properties" />
	<!-- C3P0连接池配置 -->
	<bean id="dataSource_zh_CN" class="com.mchange.v2.c3p0.ComboPooledDataSource">
		<property name="driverClass" value="${db1.jdbc.driver}" />
		<property name="jdbcUrl" value="${db1.jdbc.url}" />
		<property name="user" value="${db1.jdbc.username}" />
		<property name="password" value="${db1.jdbc.password}" />

		<!-- 配置初始化大小、最小、最大 -->
		<property name="initialPoolSize" value="${jdbc.pool.init}" />
		<property name="minPoolSize" value="${jdbc.pool.minIdle}" />
		<property name="maxPoolSize" value="${jdbc.pool.maxActive}" />
		<property name="maxIdleTime" value="60000" />
	</bean>

	<!-- C3P0连接池配置 -->
	<bean id="dataSource_en_US" class="com.mchange.v2.c3p0.ComboPooledDataSource">
		<property name="driverClass" value="${db2.jdbc.driver}" />
		<property name="jdbcUrl" value="${db2.jdbc.url}" />
		<property name="user" value="${db2.jdbc.username}" />
		<property name="password" value="${db2.jdbc.password}" />

		<!-- 配置初始化大小、最小、最大 -->
		<property name="initialPoolSize" value="${jdbc.pool.init}" />
		<property name="minPoolSize" value="${jdbc.pool.minIdle}" />
		<property name="maxPoolSize" value="${jdbc.pool.maxActive}" />
		<property name="maxIdleTime" value="60000" />
	</bean>

	<bean id="dataSource" class="com.bkc.bpmp.core.datasource.DynamicDataSource">
		<property name="targetDataSources">
			<map key-type="java.lang.String">
				<entry key="dataSource_zh_CN" value-ref="dataSource_zh_CN" />
				<entry key="dataSource_en_US" value-ref="dataSource_en_US" />
			</map>
		</property>
		<property name="defaultTargetDataSource" ref="dataSource_zh_CN" />
	</bean>

</beans>

　　

2、在 Spring 配置文件中配置 AOP 切面信息，当访问 包 com.bkc.bpmp 及下面的子包中的类的方法时

<!-- 开启aop注解方式 -->
	<aop:aspectj-autoproxy proxy-target-class="false"/>

<bean id="dataSourceInterceptor" class="com.bkc.bpmp.core.aspectj.DataSourceInterceptor" />
	
	<aop:config>
		<aop:aspect id="dataSourceAspect" ref="dataSourceInterceptor">
			<aop:pointcut id="setDs" expression="execution(* com.bkc.bpmp..*.*(..))" />
			<aop:before method="setdataSourceCnOrEn" pointcut-ref="setDs"/>
		</aop:aspect>
	</aop:config>

3、实现 数据源 切面切换的方法，这里假设是根据 locale 来切换数据源的

package com.bkc.bpmp.core.aspectj;

import java.lang.reflect.Method;

import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.reflect.MethodSignature;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.context.i18n.LocaleContextHolder;

import com.bkc.bpmp.core.annotation.DbType;
import com.bkc.bpmp.core.contants.DbTypeEnum;
import com.bkc.bpmp.core.datasource.DatabaseContextHolder;

/**
 * 用于实现 动态数据库切换的AOP 方法类
 * 
 * @author ppnie
 */
public class DataSourceInterceptor
{
    /**
     * 设置数据源为中文 还是 英文
     * @param jp
     */
    public void setdataSourceCnOrEn(JoinPoint jp) {
        
        String curLocale = LocaleContextHolder.getLocale().toString();
        System.out.println("==================dataSource_"+curLocale);
        if(curLocale.equals("en_US"))
        {
            DatabaseContextHolder.setCustomerType("dataSource_"+curLocale);
        }
        else
        {
            DatabaseContextHolder.setCustomerType("dataSource_zh_CN");
        }
        logger.info("======="+"dataSource_"+curLocale+"=======");
        
    }
}

4、自定义动态数据源的切换方法，主要就是 写一个 AbstractRoutingDataSource 的子类啦

package com.bkc.bpmp.core.datasource;

public class DatabaseContextHolder
{
    
    private static final ThreadLocal<String> contextHolder = new ThreadLocal<String>();
    
    public static void setCustomerType(String customerType)
    {
        contextHolder.set(customerType);
    }
    
    public static String getCustomerType()
    {
        return contextHolder.get();
    }
    
    public static void clearCustomerType()
    {
        contextHolder.remove();
    }
}

　　

package com.bkc.bpmp.core.datasource;

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

public class DynamicDataSource extends AbstractRoutingDataSource
{
    
    @Override
    protected Object determineCurrentLookupKey()
    {
        return DatabaseContextHolder.getCustomerType();
    }
    
}

　　

　就这样，达到触发条件的时候，就会去切换数据库啦