ActiveMQ的另一个问题就是只要是软件就有可能挂掉，挂掉不可怕，怕的是挂掉之后把信息给丢了，所以本节分析一下几种持久化方式：
一、持久化为文件
ActiveMQ默认就支持这种方式，只要在发消息时设置消息为持久化就可以了。
打开安装目录下的配置文件：
D:\ActiveMQ\apache-activemq\conf\activemq.xml在越80行会发现默认的配置项：
<persistenceAdapter>
<kahaDB directory="${activemq.data}/kahadb"/>
</persistenceAdapter>注意这里使用的是kahaDB，是一个基于文件支持事务的消息存储器，是一个可靠，高性能，可扩展的消息存储器。
他的设计初衷就是使用简单并尽可能的快。KahaDB的索引使用一个transaction log，并且所有的destination只使用一个index，有人测试表明：如果用于生产环境，支持1万个active connection，每个connection有一个独立的queue。该表现已经足矣应付大部分的需求。
然后再发送消息的时候改变第二个参数为：
MsgDeliveryMode.Persistent
Message保存方式有2种
PERSISTENT：保存到磁盘，consumer消费之后，message被删除。
NON_PERSISTENT：保存到内存，消费之后message被清除。
注意：堆积的消息太多可能导致内存溢出。
然后打开生产者端发送一个消息：
不启动消费者端，同时在管理界面查看：
发现有一个消息正在等待，这时如果没有持久化，ActiveMQ宕机后重启这个消息就是丢失，而我们现在修改为文件持久化，重启ActiveMQ后消费者仍然能够收到这个消息。
二、持久化为数据库
我们从支持Mysql为例，先从http://dev.mysql.com/downloads/connector/j/下载mysql-connector-java-5.1.34-bin.jar包放到：
D:\ActiveMQ\apache-activemq\lib目录下。
打开并修改配置文件：
<beans
xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://activemq.apache.org/schema/core http://activemq.apache.org/schema/core/activemq-core.xsd">
<!-- Allows us to use system properties as variables in this configuration file -->
<bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="locations">
<value>file:${activemq.conf}/credentials.properties</value>
</property>
</bean>
<!-- Allows accessing the server log -->
<bean id="logQuery" class="org.fusesource.insight.log.log4j.Log4jLogQuery"
lazy-init="false" scope="singleton"
init-method="start" destroy-method="stop">
</bean>
<!--
The <broker> element is used to configure the ActiveMQ broker.
-->
<broker xmlns="http://activemq.apache.org/schema/core" brokerName="localhost" dataDirectory="${activemq.data}">
<destinationPolicy>
<policyMap>
<policyEntries>
<policyEntry topic=">" >
<!-- The constantPendingMessageLimitStrategy is used to prevent
slow topic consumers to block producers and affect other consumers
by limiting the number of messages that are retained
For more information, see:
http://activemq.apache.org/slow-consumer-handling.html
-->
<pendingMessageLimitStrategy>
<constantPendingMessageLimitStrategy limit="1000"/>
</pendingMessageLimitStrategy>
</policyEntry>
</policyEntries>
</policyMap>
</destinationPolicy>
<!--
The managementContext is used to configure how ActiveMQ is exposed in
JMX. By default, ActiveMQ uses the MBean server that is started by
the JVM. For more information, see:
http://activemq.apache.org/jmx.html
-->
<managementContext>
<managementContext createConnector="false"/>
</managementContext>
<!--
Configure message persistence for the broker. The default persistence
mechanism is the KahaDB store (identified by the kahaDB tag).
For more information, see:
http://activemq.apache.org/persistence.html
<kahaDB directory="${activemq.data}/kahadb"/>
-->
<persistenceAdapter>
<jdbcPersistenceAdapter dataDirectory="${activemq.base}/data" dataSource="#derby-ds"/>
</persistenceAdapter>
<!--
The systemUsage controls the maximum amount of space the broker will
use before disabling caching and/or slowing down producers. For more information, see:
http://activemq.apache.org/producer-flow-control.html
-->
<systemUsage>
<systemUsage>
<memoryUsage>
<memoryUsage percentOfJvmHeap="70" />
</memoryUsage>
<storeUsage>
<storeUsage limit="100 gb"/>
</storeUsage>
<tempUsage>
<tempUsage limit="50 gb"/>
</tempUsage>
</systemUsage>
</systemUsage>
<!--
The transport connectors expose ActiveMQ over a given protocol to
clients and other brokers. For more information, see:
http://activemq.apache.org/configuring-transports.html
-->
<transportConnectors>
<!-- DOS protection, limit concurrent connections to 1000 and frame size to 100MB -->
<transportConnector name="openwire" uri="tcp://0.0.0.0:61616?maximumConnections=1000&wireFormat.maxFrameSize=104857600"/>
<transportConnector name="amqp" uri="amqp://0.0.0.0:5672?maximumConnections=1000&wireFormat.maxFrameSize=104857600"/>
<transportConnector name="stomp" uri="stomp://0.0.0.0:61613?maximumConnections=1000&wireFormat.maxFrameSize=104857600"/>
<transportConnector name="mqtt" uri="mqtt://0.0.0.0:1883?maximumConnections=1000&wireFormat.maxFrameSize=104857600"/>
<transportConnector name="ws" uri="ws://0.0.0.0:61614?maximumConnections=1000&wireFormat.maxFrameSize=104857600"/>
</transportConnectors>
<!-- destroy the spring context on shutdown to stop jetty -->
<shutdownHooks>
<bean xmlns="http://www.springframework.org/schema/beans" class="org.apache.activemq.hooks.SpringContextHook" />
</shutdownHooks>
</broker>
<bean id="derby-ds" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
<property name="driverClassName" value="com.mysql.jdbc.Driver"/>
<property name="url" value="jdbc:mysql://localhost/activemq?relaxAutoCommit=true"/>
<property name="username" value="root"/>
<property name="password" value=""/>
<property name="maxActive" value="200"/>
<property name="poolPreparedStatements" value="true"/>
</bean>
<!--
Enable web consoles, REST and Ajax APIs and demos
The web consoles requires by default login, you can disable this in the jetty.xml file
Take a look at ${ACTIVEMQ_HOME}/conf/jetty.xml for more details
-->
<import resource="jetty.xml"/>
</beans>
<!-- END SNIPPET: example -->
重启ActiveMQ打开phpmyadmin发现多了3张表：
然后启动生产者（不启动消费者）
在Mysql中可以找到这条消息：
关掉ActiveMQ并重启，模拟宕机。
然后启动消费者：
然后发现Mysql中已经没有这条消息了。
总结：activemq持久化方式
A：持久化为文件
这个你装ActiveMQ时默认就是这种，只要你设置消息为持久化就可以了。涉及到的配置和代码有
<
persistenceAdapter
>
<
kahaDB directory
=
"
${activemq.base}/data/kahadb
"
/>
</
persistenceAdapter
>
producer.Send(request, MsgDeliveryMode.Persistent, level, TimeSpan.MinValue);
B：持久化为MySql
你首先需要把MySql的驱动放到ActiveMQ的Lib目录下，我用的文件名字是：mysql-connector-java-5.0.4-bin.jar
接下来你修改配置文件
<
persistenceAdapter
>
<
jdbcPersistenceAdapter dataDirectory
=
"
${activemq.base}/data
"
dataSource
=
"
#derby-ds
"
/>
</
persistenceAdapter
>
在配置文件中的broker节点外增加
<
bean id
=
"
derby-ds
"
class
=
"
org.apache.commons.dbcp.BasicDataSource
"
destroy
-
method
=
"
close
"
>
<
property name
=
"
driverClassName
"
value
=
"
com.mysql.jdbc.Driver
"
/>
<
property name
=
"
url
"
value
=
"
jdbc:mysql://localhost/activemq?relaxAutoCommit=true
"
/>
<
property name
=
"
username
"
value
=
"
activemq
"
/>
<
property name
=
"
password
"
value
=
"
activemq
"
/>
<
property name
=
"
maxActive
"
value
=
"
200
"
/>
<
property name
=
"
poolPreparedStatements
"
value
=
"
true
"
/>
</
bean
>
从配置中可以看出数据库的名称是activemq，你需要手动在MySql中增加这个库。
然后重新启动消息队列，你会发现多了3张表
1：activemq_acks
2：activemq_lock
3：activemq_msgs
C：持久化为Oracle
和持久化为MySql一样。这里我说两点
1；在ActiveMQ安装文件夹里的Lib文件夹中增加Oracle的JDBC驱动。驱动文件位于Oracle客户端安装文件中的product\11.1.0\client_1\jdbc\lib文件夹下。
2：
<
bean id
=
"
derby-ds
"
class
=
"
org.apache.commons.dbcp.BasicDataSource
"
destroy
-
method
=
"
close
"
>
<
property name
=
"
driverClassName
"
value
=
"
oracle.jdbc.driver.OracleDriver
"
/>
<
property name
=
"
url
"
value
=
"
jdbc:oracle:thin:@10.53.132.47:1521:cmfudv1
"
/>
<
property name
=
"
username
"
value
=
"
qdcommu
"
/>
<
property name
=
"
password
"
value
=
"
qdcommu
"
/>
<
property name
=
"
maxActive
"
value
=
"
200
"
/>
<
property name
=
"
poolPreparedStatements
"
value
=
"
true
"
/>
</
bean
>
这里的jdbc:oracle:thin:@10.53.132.47:1521:cmfudv1按照自己实际情况设置一下就可以了，特别注意的是cmfudv1是SID即服务名称而不是TNS中配置的节点名。各位同学只需要替换IP,端口和这个SID就可以了。
