基於Tomcat + JNDI + ActiveMQ實現JMS的點對點訊息傳送，jndiactivemq

基於Tomcat + JNDI + ActiveMQ實現JMS的點對點訊息傳送，jndiactivemq

　　寫了一個簡單的JMS例子，之所以使用JNDI 是出於通用性考慮，該例子使用JMS規範提供的通用介面，沒有使用具體JMS提供者的介面，這樣可以保證我們編寫的程式適用於任何一種JMS實現(ActiveMQ、HornetQ...)。

什麼是JNDI

　　JNDI(Java Naming and Directory Interface)是一個標準規範，類似於JDBC，JMS等規範，為開發人員提供了尋找和訪問各種命名和目錄服務的通用、統一的介面。J2EE 規範要求所有 J2EE 容器都要提供 JNDI 規範的實現，因此Tomcat就實現了JNDI 規範。

使用Tomcat配置JNDI

　　找到Tomcat安裝路徑下的conf檔案夾，開啟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" /> 

啟動ActiveMQ

　　CMD到ActiveMQ安裝路徑下的bin目錄，輸入“activemq start”指令即可啟動，可在瀏覽器中輸入地址http://localhost:8161/admin，查看隊列、話題等資訊。

編寫一個Web工程

　　eclipse上建立web工程，添加ActiveMQ依賴的jar包，然後開始編寫兩個Servlet，一個用於生產訊息，另一個用於消費訊息，如下代碼：

訊息生產者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    }}

訊息消費者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    }}

驗證結果

　　在Tomcat裡運行該Web工程，執行訊息生產者Servlet，返回訊息發送成功標誌，同時我們可以在http://localhost:8161/admin/queues.jsp查看到該訊息，如所示

　　繼續執行訊息消費者Servlet，返回訊息接收成功標誌，同時我們可以開啟http://localhost:8161/admin/queues.jsp頁面，發現剛才的訊息已經不見了，如所示

 

代碼參考：http://howtodoinjava.com/jms/jms-point-to-point-message-example/