基于Tomcat + JNDI + ActiveMQ实现JMS的点对点消息传送

阅读目录

前言

什么是JNDI

使用Tomcat配置JNDI

启动ActiveMQ

编写一个Web工程

验证结果

参考资料

前言

　　写了一个简单的JMS例子，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...)。

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。

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：

<Resource name="queue/connectionFactory"
auth="Container"
type="org.apache.activemq.ActiveMQConnectionFactory"
description="JMS Connection Factory"
factory="org.apache.activemq.jndi.JNDIReferenceFactory"
brokerURL="tcp://localhost:61616"
brokerName="LocalActiveMQBroker" />

<Resource name="queue/queue0"
auth="Container"
type="org.apache.activemq.command.ActiveMQQueue"
description="My Queue"
factory="org.apache.activemq.jndi.JNDIReferenceFactory"
physicalName="TomcatQueue" />

启动ActiveMQ

　　CMD到ActiveMQ安装路径下的bin目录，输入“activemq start”指令即可启动，可在浏览器中输入地址http://localhost:8161/admin，查看队列、话题等信息。

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：

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 class Send extends HttpServlet {
private static final long serialVersionUID = 1L;

/**
* @see HttpServlet#HttpServlet()
*/
public Send() {
super();
// TODO Auto-generated constructor stub
}

/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse
*      response)
*/
protected void doGet(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
PrintWriter out = response.getWriter();

try {
// get the initial context
InitialContext context = new InitialContext();

// 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 void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
}

}

消息消费者Servlet：

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 class Receive extends HttpServlet {
private static final long serialVersionUID = 1L;

/**
* @see HttpServlet#HttpServlet()
*/
public Receive() {
super();
// TODO Auto-generated constructor stub
}

/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse
*      response)
*/
protected void doGet(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
PrintWriter out = response.getWriter();

try {
// get the initial context
InitialContext context = new InitialContext();

// 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 void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
}

}

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





　　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