這里是基于 zookeeper 選舉方式實現的集群配置，服務器過半數才可提供服務，所以是2n+1臺這里以三臺為例。
只有master節點能提供服務，slave節點無法提供服務，只有當master節點掛了，slave重新選舉出的主節點才能提供服務（灰色部分都是默認配置文件）
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<!-- START SNIPPET: example -->
<beansxmlns="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.xsdhttp://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:${activemq.conf}/credentials.properties</value></property></bean><!-- Allows accessing the server log --><bean id="logQuery" class="io.fabric8.insight.log.log4j.Log4jLogQuery"lazy-init="false" scope="singleton"init-method="start" destroy-method="stop"></bean><!--The <broker> element is used to configure the ActiveMQ broker.--><broker xmlns="http://activemq.apache.org/schema/core" brokerName="localhost" dataDirectory="${activemq.data}"><destinationPolicy><policyMap><policyEntries><policyEntry topic=">" ><!-- The constantPendingMessageLimitStrategy is used to preventslow topic consumers to block producers and affect other consumersby limiting the number of messages that are retainedFor 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 inJMX. By default, ActiveMQ uses the MBean server that is started bythe JVM. For more information, see:http://activemq.apache.org/jmx.html--><managementContext><managementContext createConnector="false"/></managementContext><!--Configure message persistence for the broker. The default persistencemechanism is the KahaDB store (identified by the kahaDB tag).For more information, see:http://activemq.apache.org/persistence.html--><!--使用zookeeper作集群配置將默認的kahadb持久化方式注釋掉，替換為leveldbreplicas = 機器總數/2+1 例如3臺機器至少需要2臺存活，7臺至少需要4臺存活bind 集群數據同步的端口(自定義只要不與本機服務器其他端口沖突即可)zkAddress zk地址,集群可以逗號隔開 ip1:2181,ip2:2181,ip3:2181hostname 本機ipzkPath mq注冊在zk的臨時節點位子
所以我們在部署集群的時候，只需要改hostname就好了,其他地方都一樣！--><persistenceAdapter><!--<kahaDB directory="${activemq.data}/kahadb"/>--><replicatedLevelDB directory="${activemq.data}/levelDB"replicas="2" bind="tcp://0.0.0.0:61615"zkAddress="10.97.47.96:2181"hostname="192.168.5.6"zkPath="/activemq/leveldb"/></persistenceAdapter><!--The systemUsage controls the maximum amount of space the broker willuse 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 toclients 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><!--Enable web consoles, REST and Ajax APIs and demosThe web consoles requires by default login, you can disable this in the jetty.xml fileTake a look at ${ACTIVEMQ_HOME}/conf/jetty.xml for more details--><import resource="jetty.xml"/>
</beans>
<!-- END SNIPPET: example --> ?測試：可以看到3臺服務器都注冊到了zk上，且只有master能提供服務！
activemq的作用、
?高可用 + 高性能的解決方案
?
