ActiveMQ-Web应用

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ActiveMQ-Web应用

sf2gis@163.com

2015年7月30日

1 目标：处理web请求消息，实现web客户端和服务端交互。

2 原理：使用servlet容器，使用ActiveMQ库将web请求转发到ActiveMQ服务器，并接收ActiveMQ的消息作为Web响应。自定义处理程序处理ActiveMQ的消息，实现对消息的控制。

3 方法：Tomcat（servlet容器）+ActiveMQ（消息服务器）+Java（消息处理程序）

参考：http://blog.sina.com.cn/s/blog_5a010cd10101djgl.html

http://jackyin5918.iteye.com/blog/2007422

http://blog.csdn.net/neareast/article/details/7588527

http://activemq.apache.org/ajax.html

3.1 建立Web网站：Tomcat，处理web请求与响应。

3.1.1添加ActiveMQ库：将下列库复制到web-inf\lib目录下。

3.2 Web消息与ActiveMQ消息映射：web.xml配置。

3.2.1web.xml设置ActiveMQ库作为响应Servlet，用于消息收发及消息与响应、请求的转换。

<servlet-name>AjaxServlet</servlet-name>

<servlet-class>org.apache.activemq.web.AjaxServlet</servlet-class>

<async-supported>true</async-supported>

</servlet>

<servlet-mapping>

<servlet-name>AjaxServlet</servlet-name>

<url-pattern>/amq/*</url-pattern>

</servlet-mapping>

3.2.2设置消息服务的url地址：context-param

参考：http://blog.csdn.net/liaoxiaohua1981/article/details/6759206

<context-param>

<param-name>org.apache.activemq.brokerURL</param-name>

<param-value>tcp://localhost:61616</param-value>

</context-param>

<welcome-file-list>

3.2.3示例

<?xmlversion="1.0" encoding="UTF-8"?>

<web-appxmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaeehttp://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"id="WebApp_ID" version="3.0">

<display-name>ajaxmq</display-name>

<servlet-name>AjaxServlet</servlet-name>

<servlet-class>org.apache.activemq.web.AjaxServlet</servlet-class>

<async-supported>true</async-supported>

</servlet>

<servlet-mapping>

<servlet-name>AjaxServlet</servlet-name>

<url-pattern>/amq/*</url-pattern>

</servlet-mapping>

<context-param>

<param-name>org.apache.activemq.brokerURL</param-name>

<param-value>tcp://localhost:61616</param-value>

</context-param>

<welcome-file-list>

<welcome-file>index.html</welcome-file>

<welcome-file>index.htm</welcome-file>

<welcome-file>index.jsp</welcome-file>

<welcome-file>default.html</welcome-file>

<welcome-file>default.htm</welcome-file>

<welcome-file>default.jsp</welcome-file>

</welcome-file-list>

</web-app>

3.3 客户端页面ActiveMQ请求：amq.js,客户端消息操作。

以Ajax的方式进行前后台交互，接收消息使用Ajax轮询来实现服务器push。

3.3.1添加amq.js及相关库：

<scripttype="text/javascript"src="js/jquery-1.4.2.min.js"></script>

<scripttype="text/javascript"src="js/amq_jquery_adapter.js"></script>

<scripttype="text/javascript" src="js/amq.js"></script>

3.3.2构造amq对象：org.activemq.Amq。需要指定uri为amq。

var amq = org.activemq.Amq;

amq.init({

uri: 'amq',

logging: true,

timeout: 20

});

3.3.3发送消息：amq.sendMessage(Destination,message,type)。

目标消息队列：Destination，使用url格式。

消息：Message，使用XML格式。

示例：

amq.sendMessage("topic://FirstTopic","<message>"+ms+"</message>","amq-msg-type=>'text'");

3.3.4接收消息：amq.addListener(cliendId,Destination,callbackFun,selector)。

目标消息队列：Destination，使用url格式。

处理函数：callbackFunction，接受一个消息参数。

选择器：selector，过滤消息。

示例：

//receive message

functionreceiverMsg(message){

console.debug("receive="+message);

document.getElementById("msg").innerHTML +="receive="+message.textContent + "<br>";

}

amq.addListener("smeguangdong","topic://FirstTopic",receiverMsg);

3.3.5示例

<!DOCTYPE html PUBLIC"-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

<metahttp-equiv="Content-Type" content="text/html;charset=UTF-8">

<title>Insert titlehere</title>

</head>

<body>

leon's chating room:

<hr>

<divstyle="height:400px;width:600px;border:block;overflow:auto"id="msg">

</div>

<br>

<scripttype="text/javascript">

//create amq

var amq = org.activemq.Amq;

amq.init({

uri: 'amq',

logging: true,

timeout: 20

});

//receive message

functionreceiverMsg(message){

console.debug("receive="+message);

document.getElementById("msg").innerHTML +="receive="+message.textContent + "<br>";

}

amq.addListener("smeguangdong","topic://FirstTopic",receiverMsg);

//send message

function sendMsg()

{

var nickname =document.getElementById("nickname").value;

var content =document.getElementById("keymsg").value;

var ms = nickname + " : "+content;

amq.sendMessage("topic://FirstTopic","<message>"+ms+"</message>","amq-msg-type=>'text'");

}

</script>

昵称：

<inputtype="text" id="nickname">

内容：

<buttononclick="sendMsg()">submit</button>

</body>

</html>

3.3.6附：amq.js源码。

/**

* Licensed to the Apache Software Foundation(ASF) under one or more

* contributor license agreements. See the NOTICE file distributed with

* this work for additional informationregarding copyright ownership.

* The ASF licenses this file to You under theApache License, Version 2.0

* (the "License"); you may not usethis file except in compliance with

* the License. You may obtain a copy of the License at

* http://www.apache.org/licenses/LICENSE-2.0

* Unless required by applicable law or agreedto in writing, software

* distributed under the License is distributedon an "AS IS" BASIS,

* WITHOUT WARRANTIES OR CONDITIONS OF ANYKIND, either express or implied.

* See the License for the specific languagegoverning permissions and

* limitations under the License.

// AMQ Ajax handler

// This class provides themain API for using the Ajax features of AMQ. It

// allows JMS messages to besent and received from javascript when used

// with theorg.apache.activemq.web.MessageListenerServlet.

// This version of the fileprovides an adapter interface for the jquery library

// and a namespace for theJavascript file, private/public variables and

// methods, and otherscripting niceties. -- jim cook 2007/08/28

var org = org || {};

org.activemq = org.activemq|| {};

org.activemq.Amq = function(){

var connectStatusHandler;

// Just a shortcut to eliminate some redundant typing.

var adapter = org.activemq.AmqAdapter;

if (typeof adapter == 'undefined') {

throw 'An org.activemq.AmqAdapter must be declared beforethe amq.js script file.'

}

// The URI of the AjaxServlet.

var uri;

// The number of seconds that the long-polling socket will stayconnected.

// Best to keep this to a value less than one minute.

var timeout;

// A session should not be considered initialized until theJSESSIONID is returned

// from the initial GET request. Otherwise subscription POSTS may register the

// subscription with the wrong session.

var sessionInitialized = false;

// This callback will be called after the first GET requestreturns.

var sessionInitializedCallback;

// Poll delay. if set to positive integer, this is the time towait in ms

// before sending the next poll after the last completes.

var pollDelay;

// Inidicates whether logging is active or not. Not by default.

var logging = false;

// 5 second delay if an error occurs during poll. This could bedue to

// server capacity problems or a timeout condition.

var pollErrorDelay = 5000;

// Map of handlers that will respond to message receipts. Theid used during

// addListener(id, destination, handler) is used to key thecallback

// handler.

var messageHandlers = {};

// Indicates whether an AJAX post call is in progress.

var batchInProgress = false;

// A collection of pending messages that accumulate when anAJAX call is in

// progress. These messages will be delivered as soon as thecurrent call

// completes. The array contains objects in the format {destination,

// message, messageType }.

var messageQueue = [];

// String to distinguish this client fromothers sharing the same session.

// This can occur when multiple browserwindows or tabs using amq.js simultaneously.

// All windows share the same JESSIONID, butneed to consume messages independently.

var clientId = null;

/**

* Iterate over thereturned XML and for each message in the response,

* invoke the handlerwith the matching id.

var messageHandler = function(data) {

var response =data.getElementsByTagName("ajax-response");

if (response != null && response.length == 1) {

connectStatusHandler(true);

var responses = response[0].childNodes; // <response>

for (var i = 0; i < responses.length; i++) {

var responseElement = responses[i];

// only process nodes of type element.....

if (responseElement.nodeType != 1) continue;

var id = responseElement.getAttribute('id');

var handler = messageHandlers[id];

if (logging && handler == null) {

adapter.log('No handler found to matchmessage with id = ' + id);

continue;

}

// Loop thru and handle each <message>

for (var j = 0; j <responseElement.childNodes.length; j++) {

handler(responseElement.childNodes[j]);

}

};

var errorHandler = function(xhr, status, ex) {

connectStatusHandler(false);

if (logging) adapter.log('Error occurred in ajax call.HTTP result: ' +

xhr.status + ', status: ' + status);

}

var pollErrorHandler = function(xhr, status, ex) {

connectStatusHandler(false);

if (status === 'error' && xhr.status === 0) {

if (logging) adapter.log('Server connectiondropped.');

setTimeout(function() { sendPoll(); },pollErrorDelay);

return;

}

if (logging) adapter.log('Error occurred in poll. HTTPresult: ' +

xhr.status + ', status: ' + status);

setTimeout(function() { sendPoll(); }, pollErrorDelay);

}

var pollHandler = function(data) {

try {

messageHandler(data);

} catch(e) {

if (logging) adapter.log('Exception in the pollhandler: ' + data, e);

throw(e);

} finally {

setTimeout(sendPoll, pollDelay);

}

};

var initHandler = function(data) {

sessionInitialized = true;

if(sessionInitializedCallback) {

sessionInitializedCallback();

}

sendPoll();

}

var sendPoll = function() {

// Workaround IE6 bug where it caches the response

// Generate a unique query string with date and random

var now = new Date();

var timeoutArg = sessionInitialized ? timeout : 0.001;

var data = 'timeout=' + timeoutArg * 1000

+'&d=' + now.getTime()

+'&r=' + Math.random();

var successCallback = sessionInitialized ? pollHandler :initHandler;

var options = { method: 'get',

data: addClientId( data ),

success: successCallback,

error: pollErrorHandler};

adapter.ajax(uri, options);

};

var sendJmsMessage = function(destination, message, type, headers){

var message = {

destination: destination,

message: message,

messageType: type

};

// Add message to outbound queue

if (batchInProgress) {

messageQueue[messageQueue.length] ={message:message, headers:headers};

} else {

org.activemq.Amq.startBatch();

adapter.ajax(uri, { method: 'post',

data: addClientId( buildParams( [message] ) ),

error: errorHandler,

headers: headers,

success: org.activemq.Amq.endBatch});

}

};

var buildParams = function(msgs) {

var s = [];

for (var i = 0, c = msgs.length; i < c; i++) {

if (i != 0) s[s.length] = '&';

s[s.length] = ((i == 0) ? 'destination' : 'd' + i);

s[s.length] = '=';

s[s.length] = msgs[i].destination;

s[s.length] = ((i == 0) ? '&message' : '&m'+ i);

s[s.length] = '=';

s[s.length] = msgs[i].message;

s[s.length] = ((i == 0) ? '&type' : '&t' +i);

s[s.length] = '=';

s[s.length] = msgs[i].messageType;

}

return s.join('');

}

// add clientId to data if it exists, before passing data toajax connection adapter.

var addClientId = function( data ) {

var output = data || '';

if( clientId ) {

if( output.length > 0 ) {

output += '&';

}

output += 'clientId='+clientId;

}

return output;

}

return {

// optional clientId can be supplied to allow multipleclients (browser windows) within the same session.

init : function(options) {

connectStatusHandler = options.connectStatusHandler|| function(connected){};

uri = options.uri || '/amq';

pollDelay = typeof options.pollDelay == 'number' ?options.pollDelay : 0;

timeout = typeof options.timeout == 'number' ?options.timeout : 25;

logging = options.logging;

sessionInitializedCallback =options.sessionInitializedCallback

clientId = options.clientId;

adapter.init(options);

sendPoll();

startBatch : function() {

batchInProgress = true;

endBatch : function() {

if (messageQueue.length > 0) {

var messagesToSend = [];

var messagesToQueue = [];

var outgoingHeaders = null;

// we need to ensure that messages which setheaders are sent by themselves.

// if 2 'listen' messages were sent together,and a 'selector' header were added to one of them,

// AMQ would add the selector to both 'listen'commands.

for(i=0;i<messageQueue.length;i++) {

// a message with headers should alwaysbe sent by itself. if other messageshave been added, send this one later.

if ( messageQueue[ i ].headers &&messagesToSend.length == 0 ) {

messagesToSend[messagesToSend.length ] = messageQueue[ i ].message;

outgoingHeaders = messageQueue[ i].headers;

} else if ( ! messageQueue[ i ].headers&& ! outgoingHeaders ) {

messagesToSend[messagesToSend.length ] = messageQueue[ i ].message;

} else {

messagesToQueue[messagesToQueue.length ] = messageQueue[ i ];

}

var body = buildParams(messagesToSend);

messageQueue = messagesToQueue;

org.activemq.Amq.startBatch();

adapter.ajax(uri, {

method: 'post',

headers: outgoingHeaders,

data: addClientId( body ),

success: org.activemq.Amq.endBatch,

error: errorHandler});

} else {

batchInProgress = false;

}

// Send a JMS message to a destination (egtopic://MY.TOPIC). Message

// should be xml or encoded xml content.

sendMessage : function(destination, message) {

sendJmsMessage(destination, message, 'send');

// Listen on a channel or topic.

// handler must be a function taking a message argument

// Supportedoptions:

// selector: Ifsupplied, it should be a SQL92 string like "property-name='value'"

// http://activemq.apache.org/selectors.html

// Example: addListener( 'handler', 'topic://test-topic',function(msg) { return msg; }, { selector:"property-name='property-value'" } )

addListener : function(id, destination, handler, options){

messageHandlers[id] = handler;

var headers = options && options.selector ?{selector:options.selector} : null;

sendJmsMessage(destination, id, 'listen', headers);

// remove Listener from channel or topic.

removeListener : function(id, destination) {

messageHandlers[id] = null;

sendJmsMessage(destination, id, 'unlisten');

// for unit testing

getMessageQueue: function() {

return messageQueue;

testPollHandler: function( data ) {

return pollHandler( data );

}

};

}();

3.4 ActiveMQ服务器：设置消息处理服务器端口，activemq.xml

参见：JMS消息服务-ActiveMQ.docx

3.5 消息处理程序：处理MQ服务器的消息。

处理ActiveMQ接收的消息。

参见：JMS消息服务-ActiveMQ.docx

4 示例：ajax轮询实现web聊天室。

参考：http://blog.sina.com.cn/s/blog_5a010cd10101djgl.html

4.1 前端页面:chat.htm

<!DOCTYPE html PUBLIC"-//W3C//DTD HTML 4.01 Transitional//EN""http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

<metahttp-equiv="Content-Type" content="text/html;charset=UTF-8">

<title>Insert titlehere</title>

<scripttype="text/javascript" src="js/jquery-1.4.2.min.js"></script>

<scripttype="text/javascript"src="js/amq_jquery_adapter.js"></script>

<scripttype="text/javascript" src="js/amq.js"></script>

</head>

<body>

leon's chating room:

<hr>

<divstyle="height:400px;width:600px;border:block;overflow:auto"id="msg">

</div>

<br>

<scripttype="text/javascript">

//create amq

var amq = org.activemq.Amq;

amq.init({

uri: 'amq',

logging: true,

timeout: 20

});

//receive message

functionreceiverMsg(message){

console.debug("receive="+message);

document.getElementById("msg").innerHTML +="receive="+message.textContent + "<br>";

}

amq.addListener("smeguangdong","topic://FirstTopic",receiverMsg);

//send message

function sendMsg()

{

var nickname =document.getElementById("nickname").value;

var content =document.getElementById("keymsg").value;

var ms = nickname + " : "+content;

amq.sendMessage("topic://FirstTopic","<message>"+ms+"</message>","amq-msg-type=>'text'");

}

</script>

昵称：

<inputtype="text" id="nickname">

内容：

<buttononclick="sendMsg()">submit</button>

</body>

</html>

4.2 Web服务器Tomcat:web.xml

<?xmlversion="1.0" encoding="UTF-8"?>

<display-name>ajaxmq</display-name>

<servlet-name>AjaxServlet</servlet-name>

<servlet-class>org.apache.activemq.web.AjaxServlet</servlet-class>

<async-supported>true</async-supported>

</servlet>

<servlet-mapping>

<servlet-name>AjaxServlet</servlet-name>

<url-pattern>/amq/*</url-pattern>

</servlet-mapping>

<context-param>

<param-name>org.apache.activemq.brokerURL</param-name>

<param-value>tcp://localhost:61616</param-value>

</context-param>

<welcome-file-list>

<welcome-file>index.html</welcome-file>

<welcome-file>index.htm</welcome-file>

<welcome-file>index.jsp</welcome-file>

<welcome-file>default.html</welcome-file>

<welcome-file>default.htm</welcome-file>

<welcome-file>default.jsp</welcome-file>

</welcome-file-list>

</web-app>

4.3 ActiveMQ服务器：ActiveMQ.xml

4.4 消息处理程序Receiver.java,Sender.java

//Receiver.java

import java.util.Date;

import javax.jms.Connection;

importjavax.jms.ConnectionFactory;

import javax.jms.Destination;

importjavax.jms.JMSException;

import javax.jms.Message;

importjavax.jms.MessageConsumer;

import javax.jms.Session;

import javax.jms.TextMessage;

importorg.apache.activemq.ActiveMQConnectionFactory;

/**

* @author sf2gis@163.com

* @date 2015年7月28日下午3:56:20

public class Receiver {

public static void main(String[] args) throws Exception {

// TODO Auto-generated method stub

receiveMsg();

}

/**

* receive messages frommq server.

* @throws JMSException

public static void receiveMsg() throws JMSException {

// create connection

ConnectionFactory cf = new ActiveMQConnectionFactory(

"tcp://localhost:61618");

Connection conn = cf.createConnection();

conn.start();

// create session

Session session = conn.createSession(false,Session.AUTO_ACKNOWLEDGE);

Destination dest =session.createTopic("FirstTopic");

MessageConsumer receiver = session.createConsumer(dest);

System.out.println("waiting msg...");

int i = 0;

while (i != 100) {

Message msg = receiver.receive();

// get msg

if (msg instanceof TextMessage) {

TextMessage txt = (TextMessage) msg;

System.out.println("ReceiveMsg " + i+ "=" + txt.getText()

+ ",now=" + newDate().toString());

} else {

System.out.println(msg);

}

++i;

}

// close

receiver.close();

session.close();

conn.close();

}

//Sender.java

import java.util.Date;

import javax.jms.Connection;

import javax.jms.Destination;

importjavax.jms.JMSException;

import javax.jms.Message;

importjavax.jms.MessageProducer;

import javax.jms.Session;

importorg.apache.activemq.ActiveMQConnectionFactory;

/**

* @author sf2gis@163.com

* @date 2015年7月28日上午11:10:51

public class Sender {

public static void main(String[] args) throws JMSException,InterruptedException {

// TODO Auto-generated method stub

sendMsg();

}

/**

* send messages to mqserver.

* @throws JMSException

* @throwsInterruptedException

public static void sendMsg() throws JMSException,InterruptedException {

// create connection

ActiveMQConnectionFactory cf = newActiveMQConnectionFactory(

"tcp://localhost:61616");

Connection conn = cf.createConnection("admin","admin");

conn.start();

System.out.println("create connection");

// create session

Session session = conn.createSession(false,Session.AUTO_ACKNOWLEDGE);

System.out.println("create session");

// create message

// Destination dest =session.createQueue("TEST.FOO");

Destination dest =session.createTopic("FirstTopic");

MessageProducer sender = session.createProducer(dest);

for (int i = 0; i < 3; ++i) {

Message msg = session

.createTextMessage("this is a msgfrom sender="+i+","

+ new Date().toString());

sender.send(msg);

Thread.sleep(1000);

}

System.out.println("send a msg");

// close

sender.close();

session.close();

conn.close();

}

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