Netty:创建WebSocket服务器和客户端

一、有点复杂的方式，自己处理协议升级、握手等信息
1.创建ServerHandler

package cn.edu.tju;

import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.handler.codec.http.FullHttpRequest;
import io.netty.handler.codec.http.FullHttpResponse;
import io.netty.handler.codec.http.websocketx.*;

public class MyWebSocketServerHandler extends SimpleChannelInboundHandler<Object> {
    private WebSocketServerHandshaker handshaker;
    @Override
    protected void channelRead0(ChannelHandlerContext ctx, Object msg) throws Exception {
        if(msg instanceof FullHttpRequest){
            handleHttpRequest(ctx,(FullHttpRequest)msg);
        }
        else if(msg instanceof WebSocketFrame){
            handleWebSocketFrame(ctx,(WebSocketFrame)msg);
        }

    }

    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) throws Exception{
        ctx.flush();
    }

    private void handleHttpRequest(ChannelHandlerContext ctx,FullHttpRequest req) throws Exception{
        if(!req.getDecoderResult().isSuccess()||(!"websocket".equals(req.headers().get("Upgrade")))){
            return;
        }
        WebSocketServerHandshakerFactory wsFactory=new WebSocketServerHandshakerFactory("ws://localhost:1234/websocket",null,false);
        handshaker=wsFactory.newHandshaker(req);
        if(handshaker==null){
            WebSocketServerHandshakerFactory.sendUnsupportedVersionResponse(ctx.channel());
        }
        else{
            handshaker.handshake(ctx.channel(),req);
        }
    }
    private void handleWebSocketFrame(ChannelHandlerContext ctx,WebSocketFrame webSocketFrame){
        if(webSocketFrame instanceof CloseWebSocketFrame){
            handshaker.close(ctx.channel(),(CloseWebSocketFrame)webSocketFrame.retain());
            return;
        }
        if(webSocketFrame instanceof PingWebSocketFrame){
            ctx.channel().write(new PongWebSocketFrame(webSocketFrame.content().retain()));
            return;
        }

        String request=((TextWebSocketFrame)webSocketFrame).text();
        System.out.println(ctx.channel()+" received: "+request);
        ctx.channel().writeAndFlush(new TextWebSocketFrame(new java.util.Date().toLocaleString()));
    }
}

2.创建WebSocket服务器：

package cn.edu.tju;


import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.*;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.codec.*;
import io.netty.handler.codec.http.HttpObjectAggregator;
import io.netty.handler.codec.http.HttpServerCodec;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;
import io.netty.handler.stream.ChunkedWriteHandler;

public class WebSocketServer {
    public static void main(String[] args) {
        EventLoopGroup bossGroup=new NioEventLoopGroup();
        EventLoopGroup workerGroup=new NioEventLoopGroup();

        try{
            ServerBootstrap serverBootstrap=new ServerBootstrap();
            serverBootstrap.group(bossGroup,workerGroup);
            serverBootstrap.channel(NioServerSocketChannel.class);
            serverBootstrap.childHandler(new ChannelInitializer<SocketChannel>() {

                @Override
                protected void initChannel(SocketChannel socketChannel) throws Exception {
                    ChannelPipeline channelPipeline=socketChannel.pipeline();
                    channelPipeline.addLast(new HttpServerCodec());
                    channelPipeline.addLast(new HttpObjectAggregator(65536));
                    channelPipeline.addLast(new ChunkedWriteHandler());
                    channelPipeline.addLast(new MyWebSocketServerHandler());

                }
            });
            ChannelFuture channelFuture=serverBootstrap.bind(1234).sync();
            channelFuture.channel().closeFuture().sync();

        }catch (Exception ex){
            System.out.println(ex.getMessage());
        }finally {
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }
}

二、更简便的方式，使用WebSocketServerProtocolHandler：
1.创建ServerHandler

package cn.edu.tju;

import io.netty.channel.Channel;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.handler.codec.http.websocketx.TextWebSocketFrame;

import java.time.LocalDateTime;

public class MyWebSocketServerHandler2 extends SimpleChannelInboundHandler<TextWebSocketFrame> {
    @Override
    protected void channelRead0(ChannelHandlerContext ctx, TextWebSocketFrame msg) throws Exception {
        Channel channel = ctx.channel();
        System.out.println(channel.remoteAddress() + ": " + msg.text());
        ctx.channel().writeAndFlush(new TextWebSocketFrame("来自服务端: " + LocalDateTime.now()));
    }

    @Override
    public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
        System.out.println("ChannelId:" + ctx.channel().id().asLongText());
    }

    @Override
    public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
        System.out.println("用户下线: " + ctx.channel().id().asLongText());
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        ctx.channel().close();
    }
}

2.创建WebSocket服务器：

package cn.edu.tju;


import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.*;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.codec.*;
import io.netty.handler.codec.http.HttpObjectAggregator;
import io.netty.handler.codec.http.HttpServerCodec;
import io.netty.handler.codec.http.websocketx.WebSocketServerProtocolHandler;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;
import io.netty.handler.stream.ChunkedWriteHandler;

public class WebSocketServer2 {
    public static void main(String[] args) {
        EventLoopGroup bossGroup=new NioEventLoopGroup();
        EventLoopGroup workerGroup=new NioEventLoopGroup();

        try{
            ServerBootstrap serverBootstrap=new ServerBootstrap();
            serverBootstrap.group(bossGroup,workerGroup);
            serverBootstrap.channel(NioServerSocketChannel.class);
            serverBootstrap.handler(new LoggingHandler(LogLevel.INFO));
            serverBootstrap.childHandler(new ChannelInitializer<SocketChannel>() {

                @Override
                protected void initChannel(SocketChannel socketChannel) throws Exception {
                    ChannelPipeline channelPipeline=socketChannel.pipeline();
                    channelPipeline.addLast(new HttpServerCodec());
                    channelPipeline.addLast(new ChunkedWriteHandler());
                    channelPipeline.addLast(new HttpObjectAggregator(8192));
                    channelPipeline.addLast(new WebSocketServerProtocolHandler("/websocket"));
                    channelPipeline.addLast(new MyWebSocketServerHandler2());

                }
            });
            ChannelFuture channelFuture=serverBootstrap.bind(1234).sync();
            channelFuture.channel().closeFuture().sync();

        }catch (Exception ex){
            System.out.println(ex.getMessage());
        }finally {
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }
}

三、连接WebSocket的html

<!DOCTYPE HTML>
<html>
<head>
    <title>WebSocket Demo</title>
</head>

<body>
<input id="text" type="text" /><br>
<button onclick="sendMessage()">发送消息</button><br>
<button onclick="closeWebSocket()">关闭连接</button>
<div id="message">
</div>
</body>

<script type="text/javascript">
    var webSocket = null;

    //判断WebSocket支持
    if('WebSocket' in window){
        webSocket = new WebSocket("ws://localhost:1234/websocket");
    }
    else{
        alert('WebSocket is not supported');
    }

    //连接发生错误的回调方法
    webSocket.onerror = function(){
        alert('连接失败');
    };

    //连接成功建立的回调方法
    webSocket.onopen = function(event){
        alert('连接成功');
    }

    //接收到消息的回调方法
    webSocket.onmessage = function(event){
        setMessageInnerHTML(event.data);
    }

    //连接关闭的回调方法
    webSocket.onclose = function(){
        alert("连接已关闭");
    }

    //当窗口关闭时关闭websocket连接
    window.onbeforeunload = function(){
        webSocket.close();
    }

    //关闭连接
    function closeWebSocket(){
        webSocket.close();
    }

    //发送消息
    function sendMessage(){
        var message = document.getElementById('text').value;
        webSocket.send(message);
    }

    //显示消息
    function setMessageInnerHTML(innerHTML){
        document.getElementById('message').innerHTML += innerHTML + '<br/>';
    }

</script>
</html>