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 Directo ...
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,為開發人員提供了查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文件夾,打開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、話題等信息。
編寫一個Web工程
eclipse上新建web工程,添加ActiveMQ依賴的jar包,然後開始編寫兩個Servlet,一個用於生產消息,另一個用於消費消息,如下代碼:
消息生產者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 } }
消息消費者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里運行該Web工程,執行消息生產者Servlet,返回消息發送成功標誌,同時我們可以在http://localhost:8161/admin/queues.jsp查看到該消息,如下圖所示
繼續執行消息消費者Servlet,返回消息接收成功標誌,同時我們可以打開http://localhost:8161/admin/queues.jsp頁面,發現剛纔的消息已經不見了,如下圖所示
代碼參考:http://howtodoinjava.com/jms/jms-point-to-point-message-example/