Netty Websocket服务器端和javascript客户端编程
2013-04-02 18:17
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[Java] Netty Websocket Server Javascript Clie
WebSocket协议的出现无疑是 HTML5 中最令人兴奋的功能特性之一,它能够很好地替代Comet技术以及Flash的XmlSocket来实现基于HTTP协议的双向通信。目前主流的浏览器,如Chrome、Firefox、IE10、Opera10、Safari等都已经支持WebSocket。另外,在服务端也出现了一些不错的WebSocket项目,如Resin、Jetty7、pywebsocket等。不过,本文将介绍的是如何使用强大的Netty框架(Netty-3.5.7.Final)来实现WebSocket服务端。Netty3框架的性能优势已无需多说,但更让开发者舒心的是,Netty3还为大家提供了非常丰富的协议实现,包括HTTP、Protobuf、WebSocket等,开发者们可以很轻松的实现自己的Socket Server。按照Netty3的常规思路,我们需要准备以下3个文件:
1、WebSocketServer.java
2、WebSocketServerHandler.java
3、WebSocketServerPipelineFactory.java
以上3个文件分别包含了主程序的逻辑、服务的处理逻辑以及Socket Pipeline的设置逻辑。Java代码实现如下:
WebSocketServer.java
[java]
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import java.net.InetSocketAddress;
import java.util.concurrent.Executors;
import org.jboss.netty.bootstrap.ServerBootstrap;
import org.jboss.netty.channel.socket.nio.NioServerSocketChannelFactory;
public class WebSocketServer
{
private final
int port;
public WebSocketServer(int port) {
this.port = port;
}
public void run() {
// 设置 Socket channel factory
ServerBootstrap bootstrap = new ServerBootstrap(
new NioServerSocketChannelFactory(
Executors.newCachedThreadPool(),
Executors.newCachedThreadPool()));
// 设置 Socket pipeline factory
bootstrap.setPipelineFactory(new WebSocketServerPipelineFactory());
// 启动服务,开始监听
bootstrap.bind(new InetSocketAddress(port));
// 打印提示信息
System.out.println("Web socket server started at port " + port +
'.');
System.out.println("Open your browser and navigate to http://localhost:" + port +
'/');
}
public static
void main(String[] args) {
int port;
if (args.length >
0) {
port = Integer.parseInt(args[0]);
} else {
port = 8080;
}
new WebSocketServer(port).run();
}
}
import java.net.InetSocketAddress; import java.util.concurrent.Executors; import org.jboss.netty.bootstrap.ServerBootstrap; import org.jboss.netty.channel.socket.nio.NioServerSocketChannelFactory; public class WebSocketServer { private final int port; public WebSocketServer(int port) { this.port = port; } public void run() { // 设置 Socket channel factory ServerBootstrap bootstrap = new ServerBootstrap( new NioServerSocketChannelFactory( Executors.newCachedThreadPool(), Executors.newCachedThreadPool())); // 设置 Socket pipeline factory bootstrap.setPipelineFactory(new WebSocketServerPipelineFactory()); // 启动服务,开始监听 bootstrap.bind(new InetSocketAddress(port)); // 打印提示信息 System.out.println("Web socket server started at port " + port + '.'); System.out.println("Open your browser and navigate to http://localhost:" + port + '/'); } public static void main(String[] args) { int port; if (args.length > 0) { port = Integer.parseInt(args[0]); } else { port = 8080; } new WebSocketServer(port).run(); } }WebSocketServerPipelineFactory.java
[java]
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import static org.jboss.netty.channel.Channels.*;
import org.jboss.netty.channel.ChannelPipeline;
import org.jboss.netty.channel.ChannelPipelineFactory;
import org.jboss.netty.handler.codec.http.HttpChunkAggregator;
import org.jboss.netty.handler.codec.http.HttpRequestDecoder;
import org.jboss.netty.handler.codec.http.HttpResponseEncoder;
public class WebSocketServerPipelineFactory
implements ChannelPipelineFactory {
public ChannelPipeline getPipeline()
throws Exception {
// pipeline 的配置与 逻辑
ChannelPipeline pipeline = pipeline();
pipeline.addLast("decoder",
new HttpRequestDecoder());
pipeline.addLast("aggregator",
new HttpChunkAggregator(65536));
pipeline.addLast("encoder",
new HttpResponseEncoder());
pipeline.addLast("handler",
new WebSocketServerHandler());
return pipeline;
}
}
import static org.jboss.netty.channel.Channels.*; import org.jboss.netty.channel.ChannelPipeline; import org.jboss.netty.channel.ChannelPipelineFactory; import org.jboss.netty.handler.codec.http.HttpChunkAggregator; import org.jboss.netty.handler.codec.http.HttpRequestDecoder; import org.jboss.netty.handler.codec.http.HttpResponseEncoder; public class WebSocketServerPipelineFactory implements ChannelPipelineFactory { public ChannelPipeline getPipeline() throws Exception { // pipeline 的配置与 逻辑 ChannelPipeline pipeline = pipeline(); pipeline.addLast("decoder", new HttpRequestDecoder()); pipeline.addLast("aggregator", new HttpChunkAggregator(65536)); pipeline.addLast("encoder", new HttpResponseEncoder()); pipeline.addLast("handler", new WebSocketServerHandler()); return pipeline; } }WebSocketServerHandler.java
[java]
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import static org.jboss.netty.handler.codec.http.HttpHeaders.*;
import static org.jboss.netty.handler.codec.http.HttpHeaders.Names.*;
import static org.jboss.netty.handler.codec.http.HttpMethod.*;
import static org.jboss.netty.handler.codec.http.HttpResponseStatus.*;
import static org.jboss.netty.handler.codec.http.HttpVersion.*;
import org.jboss.netty.buffer.ChannelBuffer;
import org.jboss.netty.buffer.ChannelBuffers;
import org.jboss.netty.channel.ChannelFuture;
import org.jboss.netty.channel.ChannelFutureListener;
import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.channel.ExceptionEvent;
import org.jboss.netty.channel.MessageEvent;
import org.jboss.netty.channel.SimpleChannelUpstreamHandler;
import org.jboss.netty.handler.codec.http.DefaultHttpResponse;
import org.jboss.netty.handler.codec.http.HttpHeaders;
import org.jboss.netty.handler.codec.http.HttpRequest;
import org.jboss.netty.handler.codec.http.HttpResponse;
import org.jboss.netty.handler.codec.http.websocketx.CloseWebSocketFrame;
import org.jboss.netty.handler.codec.http.websocketx.PingWebSocketFrame;
import org.jboss.netty.handler.codec.http.websocketx.PongWebSocketFrame;
import org.jboss.netty.handler.codec.http.websocketx.TextWebSocketFrame;
import org.jboss.netty.handler.codec.http.websocketx.WebSocketFrame;
import org.jboss.netty.handler.codec.http.websocketx.WebSocketServerHandshaker;
import org.jboss.netty.handler.codec.http.websocketx.WebSocketServerHandshakerFactory;
import org.jboss.netty.logging.InternalLogger;
import org.jboss.netty.logging.InternalLoggerFactory;
import org.jboss.netty.util.CharsetUtil;
public class WebSocketServerHandler
extends SimpleChannelUpstreamHandler
{
private static
final InternalLogger logger = InternalLoggerFactory
.getInstance(WebSocketServerHandler.class);
private static
final String WEBSOCKET_PATH = "/websocket";
private WebSocketServerHandshaker handshaker;
@Override
public void messageReceived(ChannelHandlerContext ctx, MessageEvent e)
throws Exception {
// 处理接受消息
Object msg = e.getMessage();
if (msg instanceof HttpRequest) {
handleHttpRequest(ctx, (HttpRequest) msg);
} else if (msg
instanceof WebSocketFrame) {
handleWebSocketFrame(ctx, (WebSocketFrame) msg);
}
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, ExceptionEvent e)
throws Exception {
// 处理异常情况
e.getCause().printStackTrace();
e.getChannel().close();
}
private void handleHttpRequest(ChannelHandlerContext ctx, HttpRequest req)
throws Exception {
// 只接受 HTTP GET 请求
if (req.getMethod() != GET) {
sendHttpResponse(ctx, req, new DefaultHttpResponse(HTTP_1_1,
FORBIDDEN));
return;
}
// Websocket 握手开始
WebSocketServerHandshakerFactory wsFactory =
new WebSocketServerHandshakerFactory(
getWebSocketLocation(req), null,
false);
handshaker = wsFactory.newHandshaker(req);
if (handshaker == null) {
wsFactory.sendUnsupportedWebSocketVersionResponse(ctx.getChannel());
} else {
handshaker.handshake(ctx.getChannel(), req).addListener(
WebSocketServerHandshaker.HANDSHAKE_LISTENER);
}
}
private void handleWebSocketFrame(ChannelHandlerContext ctx,
WebSocketFrame frame) {
// Websocket 握手结束
if (frame instanceof CloseWebSocketFrame) {
handshaker.close(ctx.getChannel(), (CloseWebSocketFrame) frame);
return;
} else if (frame
instanceof PingWebSocketFrame) {
ctx.getChannel().write(new PongWebSocketFrame(frame.getBinaryData()));
return;
} else if (!(frame
instanceof TextWebSocketFrame)) {
throw new UnsupportedOperationException(String.format("%s frame types not supported",
frame.getClass().getName()));
}
// 处理接受到的数据(转成大写)并返回
String request = ((TextWebSocketFrame) frame).getText();
if (logger.isDebugEnabled()) {
logger.debug(String.format("Channel %s received %s", ctx.getChannel().getId(), request));
}
ctx.getChannel().write(new TextWebSocketFrame(request.toUpperCase()));
}
private static
void sendHttpResponse(ChannelHandlerContext ctx,
HttpRequest req, HttpResponse res) {
// 返回 HTTP 错误页面
if (res.getStatus().getCode() !=
200) {
res.setContent(ChannelBuffers.copiedBuffer(res.getStatus().toString(), CharsetUtil.UTF_8));
setContentLength(res, res.getContent().readableBytes());
}
// 发送返回信息并关闭连接
ChannelFuture f = ctx.getChannel().write(res);
if (!isKeepAlive(req) || res.getStatus().getCode() !=
200) {
f.addListener(ChannelFutureListener.CLOSE);
}
}
private static String getWebSocketLocation(HttpRequest req) {
return "ws://" + req.getHeader(HttpHeaders.Names.HOST) + WEBSOCKET_PATH;
}
}
import static org.jboss.netty.handler.codec.http.HttpHeaders.*; import static org.jboss.netty.handler.codec.http.HttpHeaders.Names.*; import static org.jboss.netty.handler.codec.http.HttpMethod.*; import static org.jboss.netty.handler.codec.http.HttpResponseStatus.*; import static org.jboss.netty.handler.codec.http.HttpVersion.*; import org.jboss.netty.buffer.ChannelBuffer; import org.jboss.netty.buffer.ChannelBuffers; import org.jboss.netty.channel.ChannelFuture; import org.jboss.netty.channel.ChannelFutureListener; import org.jboss.netty.channel.ChannelHandlerContext; import org.jboss.netty.channel.ExceptionEvent; import org.jboss.netty.channel.MessageEvent; import org.jboss.netty.channel.SimpleChannelUpstreamHandler; import org.jboss.netty.handler.codec.http.DefaultHttpResponse; import org.jboss.netty.handler.codec.http.HttpHeaders; import org.jboss.netty.handler.codec.http.HttpRequest; import org.jboss.netty.handler.codec.http.HttpResponse; import org.jboss.netty.handler.codec.http.websocketx.CloseWebSocketFrame; import org.jboss.netty.handler.codec.http.websocketx.PingWebSocketFrame; import org.jboss.netty.handler.codec.http.websocketx.PongWebSocketFrame; import org.jboss.netty.handler.codec.http.websocketx.TextWebSocketFrame; import org.jboss.netty.handler.codec.http.websocketx.WebSocketFrame; import org.jboss.netty.handler.codec.http.websocketx.WebSocketServerHandshaker; import org.jboss.netty.handler.codec.http.websocketx.WebSocketServerHandshakerFactory; import org.jboss.netty.logging.InternalLogger; import org.jboss.netty.logging.InternalLoggerFactory; import org.jboss.netty.util.CharsetUtil; public class WebSocketServerHandler extends SimpleChannelUpstreamHandler { private static final InternalLogger logger = InternalLoggerFactory .getInstance(WebSocketServerHandler.class); private static final String WEBSOCKET_PATH = "/websocket"; private WebSocketServerHandshaker handshaker; @Override public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) throws Exception { // 处理接受消息 Object msg = e.getMessage(); if (msg instanceof HttpRequest) { handleHttpRequest(ctx, (HttpRequest) msg); } else if (msg instanceof WebSocketFrame) { handleWebSocketFrame(ctx, (WebSocketFrame) msg); } } @Override public void exceptionCaught(ChannelHandlerContext ctx, ExceptionEvent e) throws Exception { // 处理异常情况 e.getCause().printStackTrace(); e.getChannel().close(); } private void handleHttpRequest(ChannelHandlerContext ctx, HttpRequest req) throws Exception { // 只接受 HTTP GET 请求 if (req.getMethod() != GET) { sendHttpResponse(ctx, req, new DefaultHttpResponse(HTTP_1_1, FORBIDDEN)); return; } // Websocket 握手开始 WebSocketServerHandshakerFactory wsFactory = new WebSocketServerHandshakerFactory( getWebSocketLocation(req), null, false); handshaker = wsFactory.newHandshaker(req); if (handshaker == null) { wsFactory.sendUnsupportedWebSocketVersionResponse(ctx.getChannel()); } else { handshaker.handshake(ctx.getChannel(), req).addListener( WebSocketServerHandshaker.HANDSHAKE_LISTENER); } } private void handleWebSocketFrame(ChannelHandlerContext ctx, WebSocketFrame frame) { // Websocket 握手结束 if (frame instanceof CloseWebSocketFrame) { handshaker.close(ctx.getChannel(), (CloseWebSocketFrame) frame); return; } else if (frame instanceof PingWebSocketFrame) { ctx.getChannel().write(new PongWebSocketFrame(frame.getBinaryData())); return; } else if (!(frame instanceof TextWebSocketFrame)) { throw new UnsupportedOperationException(String.format("%s frame types not supported", frame.getClass().getName())); } // 处理接受到的数据(转成大写)并返回 String request = ((TextWebSocketFrame) frame).getText(); if (logger.isDebugEnabled()) { logger.debug(String.format("Channel %s received %s", ctx.getChannel().getId(), request)); } ctx.getChannel().write(new TextWebSocketFrame(request.toUpperCase())); } private static void sendHttpResponse(ChannelHandlerContext ctx, HttpRequest req, HttpResponse res) { // 返回 HTTP 错误页面 if (res.getStatus().getCode() != 200) { res.setContent(ChannelBuffers.copiedBuffer(res.getStatus().toString(), CharsetUtil.UTF_8)); setContentLength(res, res.getContent().readableBytes()); } // 发送返回信息并关闭连接 ChannelFuture f = ctx.getChannel().write(res); if (!isKeepAlive(req) || res.getStatus().getCode() != 200) { f.addListener(ChannelFutureListener.CLOSE); } } private static String getWebSocketLocation(HttpRequest req) { return "ws://" + req.getHeader(HttpHeaders.Names.HOST) + WEBSOCKET_PATH; } }
以上代码的逻辑还是比较清晰的:首先,在WebSocketServer中设置WebSocketServerPipelineFactory;然后,在WebSocketServerPipelineFactory中设置WebSocketServerHandler;接着,在WebSocketServerHandler处理请求并返回结果;其中,最重要的处理逻辑位于handleWebSocketFrame方法中,也就是把获取到的请求信息全部转化成大写并返回。最后,运行WebSocketServer.java就可以启动WebSocket服务,监听本地的8080端口。至此,WebSocket服务端已经全部准备就绪。这里,其实我们已经同时开发了一个简单的HTTP服务器,界面截图如下:
接下来,我们需要准备使用Javascript实现的WebSocket客户端,实现非常简单,Javascript代码实现如下:
websocket.html
[html]
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<html><head><title>Web
Socket Client</title></head>
<body>
<script
type="text/javascript">
var socket;
if (!window.WebSocket) {
window.WebSocket =
window.MozWebSocket;
}
// Javascript Websocket Client
if (window.WebSocket) {
socket = new WebSocket("ws://localhost:8080/websocket");
socket.onmessage =
function(event) {
var ta = document.getElementById('responseText');
ta.value =
ta.value + '\n' + event.data
};
socket.onopen =
function(event) {
var ta = document.getElementById('responseText');
ta.value =
"Web Socket opened!";
};
socket.onclose =
function(event) {
var ta = document.getElementById('responseText');
ta.value =
ta.value + "Web Socket closed";
};
} else {
alert("Your browser does not support Web Socket.");
}
// Send Websocket data
function send(message) {
if (!window.WebSocket) { return; }
if (socket.readyState == WebSocket.OPEN) {
socket.send(message);
} else {
alert("The socket is not open.");
}
}
</script>
<h3>Send :</h3>
<form
onsubmit="return false;">
<input
type="text" name="message"
value="Hello World!"/><input
type="button"
value="Send Web Socket Data"
onclick="send(this.form.message.value)"
/>
<h3>Receive :</h3>
<textarea
id="responseText"
style="width:500px;height:300px;"></textarea>
</form>
</body>
</html>
<html><head><title>Web Socket Client</title></head> <body> <script type="text/javascript"> var socket; if (!window.WebSocket) { window.WebSocket = window.MozWebSocket; } // Javascript Websocket Client if (window.WebSocket) { socket = new WebSocket("ws://localhost:8080/websocket"); socket.onmessage = function(event) { var ta = document.getElementById('responseText'); ta.value = ta.value + '\n' + event.data }; socket.onopen = function(event) { var ta = document.getElementById('responseText'); ta.value = "Web Socket opened!"; }; socket.onclose = function(event) { var ta = document.getElementById('responseText'); ta.value = ta.value + "Web Socket closed"; }; } else { alert("Your browser does not support Web Socket."); } // Send Websocket data function send(message) { if (!window.WebSocket) { return; } if (socket.readyState == WebSocket.OPEN) { socket.send(message); } else { alert("The socket is not open."); } } </script> <h3>Send :</h3> <form onsubmit="return false;"> <input type="text" name="message" value="Hello World!"/><input type="button" value="Send Web Socket Data" onclick="send(this.form.message.value)" /> <h3>Receive :</h3> <textarea id="responseText" style="width:500px;height:300px;"></textarea> </form> </body> </html>
以上Javascript代码的逻辑很好理解:即创建一个指向对应WebSocket地址(ws://localhost:8080/websocket)的Socket连接,进而进行发送和获取操作。其实,我们只需要把websocket.html文件放置到任意的HTTP服务器上,并打开对应URL地址,就可以看到以下的Demo界面:
输入文字“Hello World”并点击“Send Web Socket Data”按钮就可以向WebSocket的服务端发送消息了。从上图中我们还可以看到,在“Receive”下方的输出框中看到返回的消息(大写过的HELLO WORLD文字),这样一次基本的信息交互就完成了。当然,此时如果把服务端关闭,输出框中则会看到“Web Socket closed”信息。
来源:http://blog.csdn.net/shagoo/article/details/8028813
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