Jetty+Dojo+Tomcat的Comet学习笔记-HelloWorld

编程环境及配置：


Eclipse3.3 + tomcat 6.0 + dojo + jetty 6.1.9

主要讲讲jetty。

“Jetty
是一个开源的servlet容器，它为基于Java的web内容，例如JSP和servlet提供运行环境。Jetty是使用Java语言编写的，它的
API以一组JAR包的形式发布。开发人员可以将Jetty容器实例化成一个对象，可以迅速为一些独立运行（stand-alone）的Java应用提供
网络和web连接。”

Jetty里面含有实现comet技术的包。通过在Eclipse+tomcat编程环境中添加扩展jar文件的方式即可快速实现上述编程环境的配置。

首先下载jetty-6.1.9.zip（可到）

在他的/lib文件夹下面有我们所需要的所有的jar文件，找到jetty-util-6.1.9.jar，jetty-
6.1.9.jar，servlet-api-2.5-6.1.9.jar以及在/lib/cometd下面的cometd-bayeux-
6.1.9.jar，cometd-api-0.9.20080221.jar，将他们一并导入到eclipse的工程当中。

将jetty-6.1.9/contrib/cometd/bayeux/src/main/java下面的org文件夹拷贝至工程的src目录中

HelloWorld


编写HelloWorld.java

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package
cn.ict.net.lx.comet;

import
java.io.IOException;

import
java.util.HashMap;

import
java.util.Map;

import
javax.servlet.ServletException;

import
javax.servlet.http.HttpServletRequest;

import
javax.servlet.http.HttpServletResponse;

import
dojox.cometd.Bayeux;

import
dojox.cometd.Channel;

/**

* Servlet implementation class for Servlet: HelloWorld

*

*/

public

class
HelloWorld
extends
javax.servlet.http.HttpServlet
implements
javax.servlet.Servlet {

static

final

long
serialVersionUID = 1L;

/* (non-Java-doc)

* @see javax.servlet.http.HttpServlet#HttpServlet()

*/

public
HelloWorld() {

super
();

}

/* (non-Java-doc)

* @see javax.servlet.http.HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)

*/

protected

void
doGet(HttpServletRequest request, HttpServletResponse response)
throws
ServletException, IOException {

// TODO Auto-generated method stub

//response.getWriter().println("Hello");

for
(
int
i=
0
; i <
100
; i++)

publish();

}

/* (non-Java-doc)

* @see javax.servlet.http.HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)

*/

protected

void
doPost(HttpServletRequest request, HttpServletResponse response)
throws
ServletException, IOException {

// TODO Auto-generated method stub

publish();

}

public

void
publish(){

Bayeux b = (Bayeux)getServletConfig().getServletContext().getAttribute(Bayeux.DOJOX_COMETD_BAYEUX);

Channel c = b.getChannel("/hello/world"
,
false
);

Map<String, Object> message = new
HashMap<String, Object>();

message.put("test"
,
"jsp: hello world"
);

c.publish(b.newClient("server_user"
,
null
), message,
"new server message"
);

}

}

package cn.ict.net.lx.comet;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import dojox.cometd.Bayeux;
import dojox.cometd.Channel;
/**
* Servlet implementation class for Servlet: HelloWorld
*
*/
public class HelloWorld extends javax.servlet.http.HttpServlet implements javax.servlet.Servlet {
static final long serialVersionUID = 1L;

/* (non-Java-doc)
* @see javax.servlet.http.HttpServlet#HttpServlet()
*/
public HelloWorld() {
super();
}

/* (non-Java-doc)
* @see javax.servlet.http.HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
//response.getWriter().println("Hello");
for (int i=0; i < 100; i++)
publish();
}

/* (non-Java-doc)
* @see javax.servlet.http.HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
publish();
}

public void publish(){
Bayeux b = (Bayeux)getServletConfig().getServletContext().getAttribute(Bayeux.DOJOX_COMETD_BAYEUX);
Channel c = b.getChannel("/hello/world", false);
Map<String, Object> message = new HashMap<String, Object>();
message.put("test", "jsp: hello world");

c.publish(b.newClient("server_user", null), message, "new server message");
}
}

配置web工程的web.xml如下

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<?
xml

version
=
"1.0"

encoding
=
"UTF-8"
?>

<
web-app

id
=
"WebApp_ID"

version
=
"2.4"

xmlns
=
"http://java.sun.com/xml/ns/j2ee"

xmlns:xsi
=
"http://www.w3.org/2001/XMLSchema-instance"

xsi:schemaLocation
=
"http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd" >

<
display-name
>
dojoSrc
</
display-name
>

<
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
>

<
servlet
>

<
servlet-name
>
hello
</
servlet-name
>

<
servlet-class
>

cn.ict.net.lx.comet.HelloWorld

</
servlet-class
>

</
servlet
>

<
servlet-mapping
>

<
servlet-name
>
hello
</
servlet-name
>

<
url-pattern
>
/hello/*
</
url-pattern
>

</
servlet-mapping
>

<!-- 配置ContinuationCometdServlet, 这个是必须的。配置后就可以支持comted -->

<
servlet
>

<
servlet-name
>
cometd
</
servlet-name
>

<
servlet-class
>

org.mortbay.cometd.continuation.ContinuationCometdServlet

</
servlet-class
>

<
load-on-startup
>
1
</
load-on-startup
>

</
servlet
>

<!-- HelloWorld的servlet配置 -->

<
servlet
>

<
description
>

</
description
>

<
display-name
>

HelloWorld</
display-name
>

<
servlet-name
>
HelloWorld
</
servlet-name
>

<
servlet-class
>

cn.ict.net.lx.comet.HelloWorld</
servlet-class
>

</
servlet
>

<!-- Servlet映射 -->

<
servlet-mapping
>

<
servlet-name
>
cometd
</
servlet-name
>

<
url-pattern
>
/cometd/*
</
url-pattern
>

</
servlet-mapping
>

<
servlet-mapping
>

<
servlet-name
>
HelloWorld
</
servlet-name
>

<
url-pattern
>
/HelloWorld
</
url-pattern
>

</
servlet-mapping
>

</
web-app
>

<?xml version="1.0" encoding="UTF-8"?>
<web-app id="WebApp_ID" version="2.4"
xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"> <display-name>dojoSrc</display-name>
<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>
<servlet>
<servlet-name>hello</servlet-name>
<servlet-class>
cn.ict.net.lx.comet.HelloWorld
</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>hello</servlet-name>
<url-pattern>/hello/*</url-pattern>
</servlet-mapping>
<!-- 配置ContinuationCometdServlet, 这个是必须的。配置后就可以支持comted -->
<servlet>
<servlet-name>cometd</servlet-name>
<servlet-class>
org.mortbay.cometd.continuation.ContinuationCometdServlet
</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>
<!-- HelloWorld的servlet配置 -->
<servlet>
<description>
</description>
<display-name>
HelloWorld</display-name>
<servlet-name>HelloWorld</servlet-name>
<servlet-class>
cn.ict.net.lx.comet.HelloWorld</servlet-class>
</servlet>
<!-- Servlet映射 -->
<servlet-mapping>
<servlet-name>cometd</servlet-name>
<url-pattern>/cometd/*</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>HelloWorld</servlet-name>
<url-pattern>/HelloWorld</url-pattern>
</servlet-mapping>

</web-app>

编写hello.html

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

<
html
>

<
head
>

<
meta

http-equiv
=
"Content-Type"

content
=
"text/html; charset=UTF-8"
>

<
title
>
Comet Hello World
</
title
>

<
mce:script

type
=
"text/javascript"

src
=
"../dojo/dojo/dojo.js"

mce_src
=
"dojo/dojo/dojo.js"

djConfig
=
"parseOnLoad:true"
>
</
mce:script
>

<
mce:script

type
=
"text/javascript"
>
<!--

dojo.require("dojox.cometd");

dojo.require("dojox.cometd.timestamp");

function callback(msg) {

// alert(msg);

// document.write(msg);

// alert(msg.data.test);

document.body.appendChild(document.createTextNode(msg.data.test+"<
br
>
"));

}

dojox.cometd.init("/dojoSrc/cometd/cometd");

dojox.cometd.subscribe("/hello/world", callback);

// -->
</
mce:script
>

</
head
>

<
body
>

<
input

type
=
"button"

onclick
=
"dojox.cometd.publish('/hello/world', { test: 'hello world' } )"

value
=
"Click Me!"
>

</
body
>

</
html
>

<!DOCTYPE
html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html;
charset=UTF-8">
<title>Comet Hello World</title>
<mce:script type="text/javascript" src="../dojo/dojo/dojo.js"
mce_src="dojo/dojo/dojo.js"
djConfig="parseOnLoad:true"></mce:script>
<mce:script type="text/javascript"><!--
dojo.require("dojox.cometd"); dojo.require("dojox.cometd.timestamp");
function callback(msg) { // alert(msg); // document.write(msg); //
alert(msg.data.test);
document.body.appendChild(document.createTextNode(msg.data.test+"<br>"));
} dojox.cometd.init("/dojoSrc/cometd/cometd");
dojox.cometd.subscribe("/hello/world", callback);
// --></mce:script>
</head>
<body> <input type="button"
onclick="dojox.cometd.publish('/hello/world', { test: 'hello world' }
)" value="Click Me!">
</body>
</html>

分别使用IE/Firefox/Chrome访问页面hello.html：