用jetty搭建websocket服务并与ie78兼容的方法
jetty8中已经自带有websocket功能，所以我们可以很方便搭建一个自己的websocket服务。
启动类：org.noahx.websocket.WebSocketServer
访问地址：http://127.0.0.1:8085/test.html
1、外部依赖包如下（maven）
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>org.noahx</groupId>
<artifactId>ws-test</artifactId>
<version>1.0</version>
<properties>
<jetty.version>8.1.5.v20120716</jetty.version>
<slf4j.version>1.6.1</slf4j.version>
</properties>
<dependencies>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
<version>${slf4j.version}</version>
</dependency>
<dependency>
<groupId>org.eclipse.jetty</groupId>
<artifactId>jetty-server</artifactId>
<version>${jetty.version}</version>
</dependency>
<dependency>
<groupId>org.eclipse.jetty</groupId>
<artifactId>jetty-websocket</artifactId>
<version>${jetty.version}</version>
</dependency>
</dependencies>
</project>
2、搭建的websocket server，写一个服务器启动类
WebSocketServer
package org.noahx.websocket;
import org.eclipse.jetty.server.Server;
import org.eclipse.jetty.server.handler.ResourceHandler;
import org.eclipse.jetty.util.resource.FileResource;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.IOException;
import java.net.URISyntaxException;
import java.net.URL;
/**
* Created with IntelliJ IDEA.
* User: noah
* Date: 8/8/12
* Time: 5:10 PM
* To change this template use File | Settings | File Templates.
*/
public class WebSocketServer {
private Logger logger = LoggerFactory.getLogger(this.getClass());
private Server server;
private FlashPolicyServer fpServer;
private int port;
public static void main(String[] args) {
WebSocketServer server = new WebSocketServer(8085);
server.start();
}
public WebSocketServer(int port) {
this.port=port;
}
public void start(){
fpServer=new FlashPolicyServer(10843);
fpServer.start();
server = new Server(port);
MyWebSocketHandler myWebSocketHandler = new MyWebSocketHandler();
URL url=this.getClass().getClassLoader() .getResource("org/noahx/websocket/http");
ResourceHandler resourceHandler=new ResourceHandler();
try {
resourceHandler.setBaseResource(new FileResource(url));
} catch (IOException e) {
e.printStackTrace(); //To change body of catch statement use File | Settings | File Templates.
} catch (URISyntaxException e) {
e.printStackTrace(); //To change body of catch statement use File | Settings | File Templates.
}
myWebSocketHandler.setHandler(resourceHandler);
server.setHandler(myWebSocketHandler);
try {
server.start();
server.join();
} catch (Exception e) {
logger.error(e.getMessage(),e);
}
}
}
websocket服务端口我设置的为8085。通过向jetty server中加入WebSocketHandler就可以提供websocket服务了。由于WebSocketHandler是 HandlerWrapper的子类，所以这个handler中还可以再加入一个ResourceHandler。这样就可以在一个端口上同时提供 websocket与http服务。ResourceHandler指向了类路径org/noahx/websocket/http下，这个包下的所有资 源都将可以发布为web资源给http请求。
3、开发MyWebSocketHandler与MyWebSocket
MyWebSocketHandler与MyWebSocket
package org.noahx.websocket;
import org.eclipse.jetty.websocket.WebSocket;
import org.eclipse.jetty.websocket.WebSocketHandler;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;
import java.util.Timer;
/**
* Created with IntelliJ IDEA.
* User: noah
* Date: 8/8/12
* Time: 5:16 PM
* To change this template use File | Settings | File Templates.
*/
public class MyWebSocketHandler extends WebSocketHandler {
private Logger logger = LoggerFactory.getLogger(this.getClass());
@Override
public WebSocket doWebSocketConnect(HttpServletRequest request, String protocol) {
if (logger.isDebugEnabled()) {
logger.debug("url=" + request.getRequestURL() + ",protocol=" + protocol);
}
return new MyWebSocket();
}
public class MyWebSocket implements WebSocket.OnTextMessage {
private Logger logger = LoggerFactory.getLogger(this.getClass());
private Connection connection;
private Timer timer = new Timer();
@Override
public void onMessage(String data) {
if (logger.isDebugEnabled()) {
logger.debug("onMessage");
}
}
@Override
public void onOpen(Connection connection) {
if (logger.isDebugEnabled()) {
logger.debug("onOpen");
}
this.connection = connection;
timer.schedule(new MemTask(this), 0, 500);
}
@Override
public void onClose(int closeCode, String message) {
if (logger.isDebugEnabled()) {
logger.debug("onClose");
}
timer.cancel();
}
public void send(String msg) {
try {
if (logger.isDebugEnabled()) {
logger.debug("send:" + msg);
}
connection.sendMessage(msg);
} catch (IOException e) {
logger.error(e.getMessage(), e);
timer.cancel();
}
}
}
}
doWebSocketConnect中实现doWebSocketConnect方法，返回我们需要的WebSocket对象。
doWebSocketConnect方法中可以取到请求的url，所以可以当做分发器，通过url的不同分发到不同WebSocket。
如：ws://127.0.0.1:8085/ws1与ws://127.0.0.1:8085/ws2
MyWebSocket所实现的内容是以每500毫秒的速度，向浏览器发送0-100的随机数（注意这里是由服务器主动推送）。
MemTask
package org.noahx.websocket;
import java.util.Random;
import java.util.TimerTask;
/**
* Created with IntelliJ IDEA.
* User: noah
* Date: 8/8/12
* Time: 5:31 PM
* To change this template use File | Settings | File Templates.
*/
public class MemTask extends TimerTask {
private MyWebSocketHandler.MyWebSocket myWebSocket;
public MemTask(MyWebSocketHandler.MyWebSocket myWebSocket) {
this.myWebSocket = myWebSocket;
}
@Override
public void run() {
myWebSocket.send("" +new Random().nextInt(100));
}
}
取随机数的任务类
4、开发前台javascript客户机（test.html）
使用到了以下内容：
web-socket-js，https://github.com/gimite/web-socket-js/
就是这个解决了不支持html5的websocket的浏览器也可以调用websocket的问题。web-socket-js会自动判断是不是支持 html5的websocket，如果支持没有什么区别。如果发现不支持将通过Flash自动调用websocket来做socket的中转。
highcharts，http://www.highcharts.com/
这个是通过纯javascript（jquery）来绘制图表的js图表框架。来配合websocket，做到实时的动态图表。
test.html
<html>
<head>
<title></title>
<script type="text/javascript" src="swfobject.js"></script>
<script type="text/javascript" src="web_socket.js"></script>
<script type="text/javascript" src="jquery-1.7.2.min.js"></script>
<script src="hc/highcharts.js"></script>
<script src="hc/modules/exporting.js"></script>
</head>
<body>
<script type="text/javascript">
var host = window.location.host.split(":")[0];
WEB_SOCKET_SWF_LOCATION = "WebSocketMain.swf";
WEB_SOCKET_DEBUG = false;
try {
WebSocket.loadFlashPolicyFile("xmlsocket://" + host + ":10843");
} catch (e) {
}
var ws;
function init(series) {
ws = new WebSocket("ws://" + host + ":8085/");
ws.onopen = function () {
output("onOpen");
};
ws.onmessage = function (e) {
var dStr = e.data;
outputmem(dStr);
var x = (new Date()).getTime(), // current time
y = parseInt(dStr);
series.addPoint([x, y], true, true);
};
ws.onclose = function () {
output("onClose");
};
ws.onerror = function () {
output("onError");
};
}
function outputmem(str) {
var mem = document.getElementById("mem");
mem.innerHTML = str;
}
function output(str) {
var log = document.getElementById("log");
var escaped = str.replace(/&/, "&").replace(/</, "<").
replace(/>/, ">").replace(/"/, """); // "
log.innerHTML = escaped + "<br>" + log.innerHTML;
}
$(function () {
$(document).ready(function () {
Highcharts.setOptions({
global:{
useUTC:false
}
});
var chart;
chart = new Highcharts.Chart({
chart:{
renderTo:'container',
type:'spline',
marginRight:10,
events:{
load:function () {
// set up the updating of the chart each second
var series = this.series[0];
init(series);
}
}
},
title:{
text:'WebSocket random data'
},
xAxis:{
type:'datetime',
tickPixelInterval:150
},
yAxis:{
title:{
text:'Value'
},
plotLines:[
{
value:0,
width:1,
color:'#808080'
}
]
},
tooltip:{
formatter:function () {
return '<b>' + this.series.name + '</b><br/>' +
Highcharts.dateFormat('%Y-%m-%d %H:%M:%S', this.x) + '<br/>' +
Highcharts.numberFormat(this.y, 2);
}
},
legend:{
enabled:false
},
exporting:{
enabled:false
},
series:[
{
name:'Zero data',
data:(function () {
var data = [],
time = (new Date()).getTime(),
i;
for (i = -19; i <= 0; i++) {
data.push({
x:time + i * 1000,
y:0
});
}
return data;
})()
}
]
});
});
});
</script>
<div id="mem"></div>
<div id="log"></div>
<div id="container" style="min-width: 400px; height: 400px; margin: 0 auto"></div>
</body>
</html>
原理是通过web-socket-js建立与服务器的websocket连接，服务器发现连接后会主动推送数据给浏览器。
收到服务器推送过来的数据会触发onmessage，这时在onmessage中对图表进行绘制。从而达到效果。
*5、Flash Policy Server的配置
ie78可以使用websocket的关键。web-socket-js会调用flash请求websocket。
flash请求websocket也有一个前提。flash会检查安全策略文件（xml）是否允许它这样做。默认flash会请求相同host的 843端口，发送policy-file-request请求，这时返回正常的安全策略时，websocket才可以正常使用。当然我们也可以通过 WebSocket.loadFlashPolicyFile(方法重新指定策略文件url。样例是指向了10843端口，因为如果监听<1000 的端口需要root权限，所以内嵌Java版的Flash Policy Server端口为10843。
但还是建议不要手动指定WebSocket.loadFlashPolicyFile，而是用843。因为flash总是先会从843找，如果找不到再从websocket端口找（8085）。所以如果设置其它url了会影响加载速度。
Flash Policy的资料可以参考：http://www.adobe.com/devnet/flashplayer/articles/socket_policy_files.html
里面提供了一个flashpolicyd_v0.6程序，可以做Flash Policy Server，但不是java实现的。
我也写了一个Flash Policy Server，java版的
FlashPolicyServer
package org.noahx.websocket;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.SocketException;
/**
* Created with IntelliJ IDEA.
* User: noah
* Date: 8/8/12
* Time: 10:05 PM
* To change this template use File | Settings | File Templates.
*/
public class FlashPolicyServer {
private ServerSocket serverSocket;
private static Thread serverThread;
private int port;
private static boolean listening = true;
private Logger logger = LoggerFactory.getLogger(this.getClass());
public FlashPolicyServer() {
this(843);
}
public FlashPolicyServer(int port) {
this.port = port;
}
public void start() {
try {
serverThread = new Thread(new Runnable() {
public void run() {
try {
logger.info("FlashPolicyServer: Starting...");
serverSocket = new ServerSocket(port);
while (listening) {
final Socket socket = serverSocket.accept();
Thread t = new Thread(new Runnable() {
public void run() {
try {
if (logger.isDebugEnabled()) {
logger.debug("FlashPolicyServer: Handling Request...");
}
socket.setSoTimeout(10000);
InputStream in = socket.getInputStream();
byte[] buffer = new byte[23];
if (in.read(buffer) != -1 && (new String(buffer, "ISO-8859-1")).startsWith("<policy-file-request/>")) {
if (logger.isDebugEnabled()) {
logger.debug("PolicyServerServlet: Serving Policy File...");
}
OutputStream out = socket.getOutputStream();
byte[] bytes = ("<?xml version=\"1.0\"?>\n" +
"<!DOCTYPE cross-domain-policy SYSTEM \"/xml/dtds/cross-domain-policy.dtd\">\n" +
"<cross-domain-policy> \n" +
" <site-control permitted-cross-domain-policies=\"master-only\"/>\n" +
" <allow-access-from domain=\"*\" to-ports=\"*\" />\n" +
"</cross-domain-policy>").getBytes("ISO-8859-1");
out.write(bytes);
out.write(0x00);
out.flush();
out.close();
} else {
logger.warn("FlashPolicyServer: Ignoring Invalid Request");
logger.warn(" " + (new String(buffer)));
}
} catch (SocketException e) {
logger.error(e.getMessage(), e);
} catch (IOException e) {
logger.error(e.getMessage(), e);
} finally {
try {
socket.close();
} catch (Exception ex2) {
}
}
}
});
t.start();
}
} catch (IOException ex) {
logger.error("PolicyServerServlet Error---");
logger.error(ex.getMessage(), ex);
}
}
});
serverThread.start();
} catch (Exception ex) {
logger.error("PolicyServerServlet Error---");
logger.error(ex.getMessage(), ex);
}
}
public void stop() {
logger.info("FlashPolicyServer: Shutting Down...");
if (listening) {
listening = false;
}
if (!serverSocket.isClosed()) {
try {
serverSocket.close();
} catch (Exception ex) {
}
}
}
}
这样就可以和websocket server整合在一起。
安全策略文件的样例格式：
<?xml version="1.0"?>
<!DOCTYPE cross-domain-policy SYSTEM "/xml/dtds/cross-domain-policy.dtd">
<cross-domain-policy>
<site-control permitted-cross-domain-policies="master-only"/>
<allow-access-from domain="*" to-ports="*" />
</cross-domain-policy>
6、websocket展望
继ajax后websocket会给界面带来更快更好的交互效果与体验，伴随移动市场的壮大websocket也将有可能成为标准的api协议。
框架介绍：
AS3WebSocket，https://github.com/Worlize/AS3WebSocket
提供给ActiveScript3使用的websocket框架
jWebSocket，http://jwebsocket.org/
有服务器与客户端，高一级别websocket框架，提供了对基础websocket的扩展，如jsonSocket,xmlSocket,cvsSocket
kaazing（商业），http://kaazing.com/
商业级整套html5与websocket解决方案，效果最好，可惜是商业的