JMS服务器ActiveMQ的初体验并持久化消息到MySQL数据库中
JMS(Java Message Service)是jcp组织02-03年定义了jsr914规范(http://jcp.org/en/jsr/detail?id=914),它定义了消息的格式和消息传递模式;
消息包括:消息头,消息扩展属性和消息体,其结构看起来与SOAP非常的相似,但一般情况下,SOAP主要关注远程服务调用,而消息则专注于信息的交换;
消息分为:消息生产者,消息服务器和消息消费者。生产者与消费者之间是透明的,生产者在产生消息之后,把消息发送到消息服务器,再由消息服务器发给消费者,因此它们构成了JMS的3点结构;
消息服务器再给消费者时,有2种模式:点到点(ptp: point to point)模式和发布/订阅(publish/subscribe)模式;
ptp:即生产者把消息投递到消息服务器后,这条消息只能由某一个消费者使用;
发布/订阅:顾名思义,就是共享消息了,只要愿意,消费者都可以监听消息;
二、消息服务器(ActiveMQ)
消息服务器在JMS的3点结构中起着重要作用,没有它,生产者的消息不知道如何投递出去,消费者不知道从哪里取得消息,它同样是隔离生产者和消费者的关键部分…………
JMS消息服务器有很多:ActiveMQ、Jboss MQ、Open MQ、RabbitMQ、ZeroMQ等等。
本文介绍的是开源的Java实现的Apache ActiveMQ(http://activemq.apache.org),它的特性在首页就能看到,我就不再介绍了;
1、下载AMQ:http://activemq.apache.org/download.html,最新版本是5.5.0;
2、解压apache-activemq-5.5.0-bin.zip文件到文件系统(比如D:\ActiveMQ-5.5.0);
3、执行bin/activemq.bat脚本即可启动AMQ:
- INFO | ActiveMQ 5.5.0 JMS Message Broker (localhost) is starting
- ......
- INFO | Listening for connections at: tcp://SHI-AP33382A:61616
当看到上面的日志输出时,表示AMQ已经启动了;
4、默认情况下,AMQ使用conf/activemq.xml作为配置文件,我们可修改它,然后以 bin/activemq.bat xbean:./conf/my.xml启动AMQ;
三、持久化消息(MySQL)
因为接下来我们修改AMQ的默认配置文件,所以先备份conf/activemq.xml文件;
1、建立MySQL数据库:要使用MySQL存储消息,必须告诉AMQ数据源:
- /**
- * 创建数据库
- */
- CREATE DATABASE misc DEFAULT CHARSET=UTF8;
- /**
- * 创建用户和授权
- */
- GRANT ALL PRIVILEGES ON misc.* TO 'misc_root'@'%' IDENTIFIED BY 'misc_root_pwd';
- GRANT ALL PRIVILEGES ON misc.* TO 'misc_root'@'localhost' IDENTIFIED BY 'misc_root_pwd';
通过上面的SQL脚本,我们建立了名为misc的数据库,并且把所有权限都赋予了misc_root的用户;
由于AMQ需要在本数据库中建立数据表,因此用户的权限必须具有建表权限;
2、添加MySQL数据源:默认情况下,AMQ使用KahaDB存储(我对KahaDB不了解),注释到KahaDB的配置方式,改为MySQL的:
- <!--
- <persistenceAdapter>
- <kahaDB directory="${activemq.base}/data/kahadb"/>
- </persistenceAdapter>
- -->
- <persistenceAdapter>
- <jdbcPersistenceAdapter dataSource="#MySQL-DS"/>
- </persistenceAdapter>
该配置表示,我们将要使用一个叫做“MySQL-DS”的JDBC数据源;
3、配置MySQL数据源:在</broker>节点后面,增加MySQL数据源配置:
- <!-- MySQL DataSource -->
- <bean id="MySQL-DS" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
- <property name="driverClassName" value="com.mysql.jdbc.Driver"/>
- <property name="url" value="jdbc:mysql://127.0.0.1:3306/misc?useUnicode=true&characterEncoding=UTF-8"/>
- <property name="username" value="misc_root"/>
- <property name="password" value="misc_root_pwd"/>
- <property name="poolPreparedStatements" value="true"/>
- </bean>
其实这就是一个Spring的Bean的配置,注意id与上面的保持一致;
整个AMQ的配置文件内容为:
- <?xml version="1.0" encoding="UTF-8"?>
- <beans xmlns="http://www.springframework.org/schema/beans" xmlns:amq="http://activemq.apache.org/schema/core" 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>classpath:/META-INF/credentials.properties</value>
- </property>
- </bean>
- <!--
- The <broker> element is used to configure the ActiveMQ broker.
- -->
- <broker xmlns="http://activemq.apache.org/schema/core" brokerName="localhost">
- <!--
- For better performances use VM cursor and small memory limit. For more information, see: http://activemq.apache.org/message-cursors.html Also, if your producer is "hanging", it's probably due to producer flow control. For more information, see:
- http://activemq.apache.org/producer-flow-control.html
- -->
- <destinationPolicy>
- <policyMap>
- <policyEntries>
- <policyEntry topic=">" producerFlowControl="true" memoryLimit="1mb">
- <pendingSubscriberPolicy>
- <vmCursor />
- </pendingSubscriberPolicy>
- </policyEntry>
- <policyEntry queue=">" producerFlowControl="true" memoryLimit="1mb">
- <!--
- Use VM cursor for better latency For more information, see: http://activemq.apache.org/message-cursors.html <pendingQueuePolicy> <vmQueueCursor/> </pendingQueuePolicy>
- -->
- </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
- -->
- <!--
- <persistenceAdapter>
- <kahaDB directory="${activemq.base}/data/kahadb"/>
- </persistenceAdapter>
- -->
- <persistenceAdapter>
- <jdbcPersistenceAdapter dataSource="#MySQL-DS" />
- </persistenceAdapter>
- <!--
- 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>
- <transportConnector name="openwire" uri="tcp://0.0.0.0:61616" />
- </transportConnectors>
- </broker>
- <!-- MySQL DataSource -->
- <bean id="MySQL-DS" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
- <property name="driverClassName" value="com.mysql.jdbc.Driver" />
- <property name="url" value="jdbc:mysql://127.0.0.1:3306/misc?useUnicode=true&characterEncoding=UTF-8" />
- <property name="username" value="misc_root" />
- <property name="password" value="misc_root_pwd" />
- <property name="poolPreparedStatements" value="true" />
- </bean>
- <!--
- Enable web consoles, REST and Ajax APIs and demos
- It also includes Camel (with its web console), see ${ACTIVEMQ_HOME}/conf/camel.xml for more info
- Take a look at ${ACTIVEMQ_HOME}/conf/jetty.xml for more details
- -->
- <import resource="jetty.xml"/>
- </beans>
四、查看MySQL数据表
重新启动AMQ,启动完成之后,我们发现,misc数据库多了3张数据表:
- mysql> SHOW tables;
- +----------------+
- | Tables_in_misc |
- +----------------+
- | activemq_acks |
- | activemq_lock |
- | activemq_msgs |
- +----------------+
数据表activemq_msgs即为持久化消息表;
五、持久化消息
系统启动完毕之后,消息表中内容为空:
- mysql> SELECT * FROM activemq_msgs;
- Empty set
1、发送消息:打开http://127.0.0.1:8161/demo/页面,找到“Send a message”链接,打开页面(http://127.0.0.1:8161/demo/send.html),填写完表格后,点击“Send”按键,即AMQ投递了一个消息;
2、查看消息:发送之后,我们可以看到数据表中多了一条消息:
- mysql> SELECT * FROM activemq_msgs;
- +----+-----------------+--------------------------------------------+-----------+------------+-----+----------+
- | ID | CONTAINER | MSGID_PROD | MSGID_SEQ | EXPIRATION | MSG | PRIORITY |
- +----+-----------------+--------------------------------------------+-----------+------------+-----+----------+
- | 1 | queue://FOO.BAR | ID:SHI-AP33382A-1486-1309840138441-2:2:1:1 | 1 | 0 | | 5 |
- +----+-----------------+--------------------------------------------+-----------+------------+-----+----------+
3、取得消息:找到“Receive a message”链接,打开页面(http://127.0.0.1:8161/demo/message/FOO/BAR?readTimeout=10000&type=queue),发现该页面不是一个标准HTML页面,查看其源代码,其内容是不是就是刚才的消息内容?
4、查看消息:消息消费之后,我们可以看到数据表没有消息了:
- mysql> SELECT * FROM activemq_msgs;
- Empty set
5、我们可以生产多条消息,然后一条一条的消费,发现消息表中的消息一条一条的减少;
6、在发送消息页面,“Destination Type”如果选择“Topic”的话,则消息表中并没有数据,原因在于“Queue”为ptp模式消息,“Topic”为发布/订阅模式消息,当没有订阅者时,消息直接丢掉了。
JMS的内容先介绍到这里,下面我将结合Spring来启动AMQ(即AMQ与应用一同启动,上面介绍的都是单独的启动),通过测试代码来发送和消费消息,敬请期待!
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