java tomcat jms_JavaWeb之使用Tomcat、JNDI与ActiveMQ实现JMS消息通信服务

本文通过JavaWeb应用,利用Tomcat的JNDI配置,结合ActiveMQ实现JMS的PTP和Pub/Sub两种消息模式。详细介绍了生产者和消费者Servlet的编写过程,展示了如何发送和接收消息。

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前言

之所以使用JNDI 是出于通用性考虑,该例子使用JMS规范提供的通用接口,没有使用具体JMS提供者的接口,这样可以保证我们编写的程序适用于任何一种JMS实现(ActiveMQ、HornetQ等)。

什么是JNDI:JNDI(Java Naming and Directory Interface)是一个标准规范,类似于JDBC,JMS等规范,为开发人员提供了查找和访问各种命名和目录服务的通用、统一的接口。J2EE 规范要求所有 J2EE 容器都要提供 JNDI 规范的实现,因此Tomcat就实现了JNDI 规范。

PTP(Point to point)消息模式(JMS的点对点消息传送)

1、使用Tomcat配置JNDI

找到Tomcat安装路径下的conf文件夹,打开context.xml,添加如下配置:

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2、启动ActiveMQ

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3、编写一个Web工程

Eclipse上新建web工程,添加ActiveMQ依赖的jar包,然后开始编写两个Servlet,一个用于生产消息,另一个用于消费消息,如下代码:

消息生产者Servlet:

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import java.io.IOException;

import java.io.PrintWriter;

import javax.jms.DeliveryMode;

import javax.jms.Queue;

import javax.jms.QueueConnection;

import javax.jms.QueueConnectionFactory;

import javax.jms.QueueSender;

import javax.jms.QueueSession;

import javax.jms.Session;

import javax.jms.TextMessage;

import javax.naming.InitialContext;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;/**

* Servlet implementation class JMSTest*/@WebServlet("/Send")public classSend extends HttpServlet {private static final long serialVersionUID = 1L;/**

* @see HttpServlet#HttpServlet()*/

publicSend() {

super();//TODO Auto-generated constructor stub

}/**

* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse

* response)*/

protected voiddoGet(HttpServletRequest request,

HttpServletResponse response) throws ServletException, IOException {

PrintWriterout =response.getWriter();try{//get the initial context

InitialContext context = newInitialContext();//lookup the queue object

Queue queue = (Queue) context.lookup("java:comp/env/queue/queue0");//lookup the queue connection factory

QueueConnectionFactory conFactory =(QueueConnectionFactory) context

.lookup("java:comp/env/queue/connectionFactory");//create a queue connection

QueueConnection queConn =conFactory.createQueueConnection();//create a queue session

QueueSession queSession = queConn.createQueueSession(false,

Session.DUPS_OK_ACKNOWLEDGE);//create a queue sender

QueueSender queSender =queSession.createSender(queue);

queSender.setDeliveryMode(DeliveryMode.NON_PERSISTENT);//create a simple message to say "Hello World"

TextMessage message = queSession.createTextMessage("Hello World");//send the message

queSender.send(message);//print what we did

out.write("Message Sent:" +message.getText());//close the queue connection

queConn.close();

}catch(Exception e) {//TODO Auto-generated catch block

e.printStackTrace();

}

}/**

* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse

* response)*/

protected voiddoPost(HttpServletRequest request,

HttpServletResponse response) throws ServletException, IOException {//TODO Auto-generated method stub

}

}

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消息消费者Servlet:

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import java.io.IOException;

import java.io.PrintWriter;

import javax.jms.Queue;

import javax.jms.QueueConnection;

import javax.jms.QueueConnectionFactory;

import javax.jms.QueueReceiver;

import javax.jms.QueueSession;

import javax.jms.Session;

import javax.jms.TextMessage;

import javax.naming.InitialContext;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;/**

* Servlet implementation class Receive*/@WebServlet("/Receive")public classReceive extends HttpServlet {private static final long serialVersionUID = 1L;/**

* @see HttpServlet#HttpServlet()*/

publicReceive() {

super();//TODO Auto-generated constructor stub

}/**

* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse

* response)*/

protected voiddoGet(HttpServletRequest request,

HttpServletResponse response) throws ServletException, IOException {

PrintWriterout =response.getWriter();try{//get the initial context

InitialContext context = newInitialContext();//lookup the queue object

Queue queue = (Queue) context.lookup("java:comp/env/queue/queue0");//lookup the queue connection factory

QueueConnectionFactory conFactory =(QueueConnectionFactory) context

.lookup("java:comp/env/queue/connectionFactory");//create a queue connection

QueueConnection queConn =conFactory.createQueueConnection();//create a queue session

QueueSession queSession = queConn.createQueueSession(false,

Session.AUTO_ACKNOWLEDGE);//create a queue receiver

QueueReceiver queReceiver =queSession.createReceiver(queue);//start the connection

queConn.start();//receive a message

TextMessage message =(TextMessage) queReceiver.receive();//print the message

out.write("Message Received:" +message.getText());//close the queue connection

queConn.close();

}catch(Exception e) {//TODO Auto-generated catch block

e.printStackTrace();

}

}/**

* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse

* response)*/

protected voiddoPost(HttpServletRequest request,

HttpServletResponse response) throws ServletException, IOException {//TODO Auto-generated method stub

}

}

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4、验证结果

在Tomcat里运行该Web工程,执行消息生产者Servlet,返回消息发送成功标志,同时我们可以在http://localhost:8161/admin/queues.jsp查看到该消息,如下图所示

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继续执行消息消费者Servlet,返回消息接收成功标志,同时我们可以打开http://localhost:8161/admin/queues.jsp页面,发现刚才的消息已经不见了,如下图所示

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Pub/Sub消息模式(JMS发布/订阅消息传送)

1、在Tomcat中配置JNDI

配置连接工厂和话题:

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2、启动ActiveMQ

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3、在Web工厂中编写代码

新建一个发布者Servlet:

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package pubSub;

import java.io.IOException;

import java.io.PrintWriter;

import javax.naming.InitialContext;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import javax.jms.Topic;

import javax.jms.Session;

import javax.jms.TextMessage;

import javax.jms.TopicPublisher;

import javax.jms.DeliveryMode;

import javax.jms.TopicSession;

import javax.jms.TopicConnection;

import javax.jms.TopicConnectionFactory;/**

* Servlet implementation class JMSTest*/@WebServlet("/Publish")public classPublisher extends HttpServlet {private static final long serialVersionUID = 1L;/**

* @see HttpServlet#HttpServlet()*/

publicPublisher() {

super();//TODO Auto-generated constructor stub

}/**

* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse

* response)*/

protected voiddoGet(HttpServletRequest request,

HttpServletResponse response) throws ServletException, IOException {

PrintWriterout =response.getWriter();try{//get the initial context

InitialContext ctx = newInitialContext();//lookup the topic object

Topic topic = (Topic) ctx.lookup("java:comp/env/topic/topic0");//lookup the topic connection factory

TopicConnectionFactory connFactory =(TopicConnectionFactory) ctx

.lookup("java:comp/env/topic/connectionFactory");//create a topic connection

TopicConnection topicConn =connFactory.createTopicConnection();//create a topic session

TopicSession topicSession = topicConn.createTopicSession(false,

Session.AUTO_ACKNOWLEDGE);//create a topic publisher

TopicPublisher topicPublisher =topicSession.createPublisher(topic);

topicPublisher.setDeliveryMode(DeliveryMode.NON_PERSISTENT);//create the "Hello World" message

TextMessage message =topicSession.createTextMessage();

message.setText("Hello World");//publish the messages

topicPublisher.publish(message);//print what we did

out.write("Message published:" +message.getText());//close the topic connection

topicConn.close();

}catch(Exception e) {//TODO Auto-generated catch block

e.printStackTrace();

}

}/**

* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse

* response)*/

protected voiddoPost(HttpServletRequest request,

HttpServletResponse response) throws ServletException, IOException {//TODO Auto-generated method stub

}

}

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新建一个订阅者Servlet:

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package pubSub;

import java.io.IOException;

import java.io.PrintWriter;

import javax.jms.Session;

import javax.jms.TextMessage;

import javax.jms.Topic;

import javax.jms.TopicConnection;

import javax.jms.TopicConnectionFactory;

import javax.jms.TopicSession;

import javax.jms.TopicSubscriber;

import javax.naming.InitialContext;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;/**

* Servlet implementation class Receive*/@WebServlet("/Subscribe")public classSubscriber extends HttpServlet {private static final long serialVersionUID = 1L;/**

* @see HttpServlet#HttpServlet()*/

publicSubscriber() {

super();//TODO Auto-generated constructor stub

}/**

* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse

* response)*/

protected voiddoGet(HttpServletRequest request,

HttpServletResponse response) throws ServletException, IOException {

PrintWriterout =response.getWriter();try{//get the initial context

InitialContext ctx = newInitialContext();//lookup the topic object

Topic topic = (Topic) ctx.lookup("java:comp/env/topic/topic0");//lookup the topic connection factory

TopicConnectionFactory connFactory =(TopicConnectionFactory) ctx

.lookup("java:comp/env/topic/connectionFactory");//create a topic connection

TopicConnection topicConn =connFactory.createTopicConnection();//create a topic session

TopicSession topicSession = topicConn.createTopicSession(false,

Session.AUTO_ACKNOWLEDGE);//create a topic subscriber

TopicSubscriber topicSubscriber =topicSession

.createSubscriber(topic);//start the connection

topicConn.start();//receive the message

TextMessage message =(TextMessage) topicSubscriber.receive();//print the message

out.write("Message received:" +message.getText());//close the topic connection

topicConn.close();

}catch(Exception e) {//TODO Auto-generated catch block

e.printStackTrace();

}

}/**

* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse

* response)*/

protected voiddoPost(HttpServletRequest request,

HttpServletResponse response) throws ServletException, IOException {//TODO Auto-generated method stub

}

}

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4、验证结果

运行Web工程,分别打开多个标签访问订阅servlet,然后访问发布servlet,结果如下:

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在订阅者订阅消息的时候,一开始没接收到消息,一旦发布者发布消息后,订阅者马上收到消息。

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