[Java] Netty Websocket Server Javascript Client

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]
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]
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]
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(

补充：软件开发 , Java ,