基于Netty+WebSocket的网页聊天简单实现

一、pom依赖

<dependency>
        <groupId>io.netty</groupId>
        <artifactId>netty-all</artifactId>
        <version>4.1.6.Final</version>
        </dependency>

二、文件目录

三、服务端代码

WebSocketService

package com.netty;

import io.netty.channel.ChannelHandlerContext;

import io.netty.handler.codec.http.websocketx.WebSocketFrame;

public interface WebSocketService {

    void handleFrame(ChannelHandlerContext ctx,WebSocketFrame frame);

}

HttpService

package com.netty;

import io.netty.channel.ChannelHandlerContext;

import io.netty.handler.codec.http.FullHttpRequest;

public interface HttpService {

    void handleHttpRequset(ChannelHandlerContext ctx,FullHttpRequest request);

}

WebSocketServerHandler

package com.netty;

import io.netty.channel.ChannelHandlerContext;

import io.netty.channel.SimpleChannelInboundHandler;

import io.netty.handler.codec.http.FullHttpRequest;

import io.netty.handler.codec.http.websocketx.WebSocketFrame;

public class WebSocketServerHandler extends SimpleChannelInboundHandler<Object>{

    private WebSocketService webSocketServiceImpl;

    private HttpService httpServiceImpl;

    public WebSocketServerHandler(WebSocketService webSocketServiceImpl,

            HttpService httpServiceImpl) {

        super();

        this.webSocketServiceImpl = webSocketServiceImpl;

        this.httpServiceImpl = httpServiceImpl;

    }

    @Override

    protected void channelRead0(ChannelHandlerContext ctx, Object msg)

            throws Exception {

        // TODO Auto-generated method stub

        if(msg instanceof FullHttpRequest){

            httpServiceImpl.handleHttpRequset(ctx, (FullHttpRequest)msg);

        }else if(msg instanceof WebSocketFrame){

            webSocketServiceImpl.handleFrame(ctx, (WebSocketFrame)msg);

        }

    }

    @Override

    public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {

        // TODO Auto-generated method stub

        ctx.flush();

    }

}

WebSocketServerImpl

package com.netty;

import java.util.Map;

import java.util.concurrent.ConcurrentHashMap;

import io.netty.bootstrap.ServerBootstrap;

import io.netty.channel.Channel;

import io.netty.channel.ChannelFuture;

import io.netty.channel.ChannelFutureListener;

import io.netty.channel.ChannelHandlerContext;

import io.netty.channel.ChannelId;

import io.netty.channel.ChannelInitializer;

import io.netty.channel.ChannelPipeline;

import io.netty.channel.EventLoopGroup;

import io.netty.channel.nio.NioEventLoopGroup;

import io.netty.channel.socket.nio.NioServerSocketChannel;

import io.netty.handler.codec.http.FullHttpRequest;

import io.netty.handler.codec.http.HttpHeaderNames;

import io.netty.handler.codec.http.HttpHeaders;

import io.netty.handler.codec.http.HttpMethod;

import io.netty.handler.codec.http.HttpObjectAggregator;

import io.netty.handler.codec.http.HttpServerCodec;

import io.netty.handler.codec.http.websocketx.CloseWebSocketFrame;

import io.netty.handler.codec.http.websocketx.PingWebSocketFrame;

import io.netty.handler.codec.http.websocketx.PongWebSocketFrame;

import io.netty.handler.codec.http.websocketx.TextWebSocketFrame;

import io.netty.handler.codec.http.websocketx.WebSocketFrame;

import io.netty.handler.codec.http.websocketx.WebSocketServerHandshaker;

import io.netty.handler.codec.http.websocketx.WebSocketServerHandshakerFactory;

import io.netty.handler.stream.ChunkedWriteHandler;

import io.netty.util.AttributeKey;

public class WebSocketServerImpl implements WebSocketService, HttpService{

    private static final String HN_HTTP_CODEC = "HN_HTTP_CODEC";

    private static final String NH_HTTP_AGGREGATOR ="NH_HTTP_AGGREGATOR";

    private static final String NH_HTTP_CHUNK = "HN_HTTP_CHUNK";

    private static final String NH_SERVER = "NH_LOGIC";

    private static final AttributeKey<WebSocketServerHandshaker> ATTR_HANDSHAKER = AttributeKey.newInstance("ATTR_KEY_CHANNELID");

    private static final int MAX_CONTENT_LENGTH = 65536;

    private static final String WEBSOCKET_UPGRADE = "websocket";

    private static final String WEBSOCKET_CONNECTION = "Upgrade";

    private static final String WEBSOCKET_URI_ROOT_PATTERN = "ws://%s:%d";

    //地址

    private String host;

    //端口号

    private int port;

    //存放websocket连接

    private Map<ChannelId, Channel> channelMap = new ConcurrentHashMap<ChannelId, Channel>();

    private final String WEBSOCKET_URI_ROOT;

    public WebSocketServerImpl(String host, int port) {

        super();

        this.host = host;

        this.port = port;

        WEBSOCKET_URI_ROOT = String.format(WEBSOCKET_URI_ROOT_PATTERN, host, port);

    }

    //启动

    public void start(){

        EventLoopGroup bossGroup = new NioEventLoopGroup();

        EventLoopGroup workerGroup = new NioEventLoopGroup();

        ServerBootstrap sb = new ServerBootstrap();

        sb.group(bossGroup, workerGroup);

        sb.channel(NioServerSocketChannel.class);

        sb.childHandler(new ChannelInitializer<Channel>() {

            @Override

            protected void initChannel(Channel ch) throws Exception {

                // TODO Auto-generated method stub

                ChannelPipeline pl = ch.pipeline();

                //保存引用

                channelMap.put(ch.id(), ch);

                ch.closeFuture().addListener(new ChannelFutureListener() {

                    @Override

                    public void operationComplete(ChannelFuture future) throws Exception {

                        // TODO Auto-generated method stub

                        //关闭后抛弃

                        channelMap.remove(future.channel().id());

                    }

                });

            pl.addLast(HN_HTTP_CODEC,new HttpServerCodec());

            pl.addLast(NH_HTTP_AGGREGATOR,new HttpObjectAggregator(MAX_CONTENT_LENGTH));

            pl.addLast(NH_HTTP_CHUNK,new ChunkedWriteHandler());

            pl.addLast(NH_SERVER,new WebSocketServerHandler(WebSocketServerImpl.this,WebSocketServerImpl.this));

            }

        });

        try {

            ChannelFuture future = sb.bind(host,port).addListener(new ChannelFutureListener() {

                @Override

                public void operationComplete(ChannelFuture future) throws Exception {

                    // TODO Auto-generated method stub

                    if(future.isSuccess()){

                        System.out.println("websocket started");

                    }

                }

            }).sync();

            future.channel().closeFuture().addListener(new ChannelFutureListener() {

                @Override

                public void operationComplete(ChannelFuture future) throws Exception {

                    // TODO Auto-generated method stub

                    System.out.println("channel is closed");

                }

            }).sync();

        } catch (InterruptedException e) {

            // TODO Auto-generated catch block

            e.printStackTrace();

        } finally{

            bossGroup.shutdownGracefully();

            workerGroup.shutdownGracefully();

        }

        System.out.println("websocket shutdown");

    }

    @Override

    public void handleHttpRequset(ChannelHandlerContext ctx,

            FullHttpRequest request) {

        // TODO Auto-generated method stub

        if(isWebSocketUpgrade(request)){

            String subProtocols = request.headers().get(HttpHeaderNames.SEC_WEBSOCKET_PROTOCOL);

            WebSocketServerHandshakerFactory factory = new WebSocketServerHandshakerFactory(WEBSOCKET_URI_ROOT, subProtocols, false);

            WebSocketServerHandshaker handshaker = factory.newHandshaker(request);

            if(handshaker == null){

                WebSocketServerHandshakerFactory.sendUnsupportedVersionResponse(ctx.channel());

            }else{

                //响应请求

                handshaker.handshake(ctx.channel(), request);

                //将handshaker绑定给channel

                ctx.channel().attr(ATTR_HANDSHAKER).set(handshaker);

            }

            return;

        }

    }

    @Override

    public void handleFrame(ChannelHandlerContext ctx, WebSocketFrame frame) {

        // TODO Auto-generated method stub

        if(frame instanceof TextWebSocketFrame){

            String text = ((TextWebSocketFrame) frame).text();

            TextWebSocketFrame rsp = new TextWebSocketFrame(text);

            for(Channel ch:channelMap.values()){

                if(ctx.channel().equals(ch)){

                    continue;

                }

                ch.writeAndFlush(rsp);

            }

            return;

        }

        //ping 回复 pong

        if(frame instanceof PingWebSocketFrame){

            ctx.channel().writeAndFlush(new PongWebSocketFrame(frame.content().retain()));

            return;

        }

        if(frame instanceof PongWebSocketFrame){

            return;

        }

        if(frame instanceof CloseWebSocketFrame){

            WebSocketServerHandshaker handshaker = ctx.channel().attr(ATTR_HANDSHAKER).get();

            if(handshaker == null){

                return;

            }

            handshaker.close(ctx.channel(), (CloseWebSocketFrame)frame.retain());

            return;

        }

    }

    //1、判断是否为get 2、判断Upgrade头 包含websocket字符串 3、Connection头 包换upgrade字符串

    private boolean isWebSocketUpgrade(FullHttpRequest request){

        HttpHeaders headers = request.headers();

        return request.method().equals(HttpMethod.GET)

                && headers.get(HttpHeaderNames.UPGRADE).contains(WEBSOCKET_UPGRADE)

                && headers.get(HttpHeaderNames.CONNECTION).contains(WEBSOCKET_CONNECTION);

    }

}

DoMain

package com.netty;

public class DoMain {

    public static void main(String[] args) {

        WebSocketServerImpl socket = new WebSocketServerImpl("localhost", 9999);

        socket.start();

    }

}

四、服务端代码

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">

<head>

<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />

<title></title>

</head>

  </head>

  <script type="text/javascript">

  var socket;  

  if(!window.WebSocket){

      window.WebSocket = window.MozWebSocket;

  }  

  if(window.WebSocket){

      socket = new WebSocket("ws://localhost:9999");  

      socket.onmessage = function(event){

            appendln("receive:" + event.data);

      };  

      socket.onopen = function(event){

            appendln("WebSocket is opened");  

      };  

      socket.onclose = function(event){

            appendln("WebSocket is closed");

      };

  }else{

        alert("WebSocket is not support");

  }  

  function send(message){

    if(!window.WebSocket){return;}

    if(socket.readyState == WebSocket.OPEN){

        socket.send(message);

        appendln("send:" + message);

    }else{

        alert("WebSocket is failed");

    }  

  }  

  function appendln(text) {

    var ta = document.getElementById('responseText');

    ta.value += text + "\r\n";

  }  

  function clear() {

    var ta = document.getElementById('responseText');

    ta.value = "";

  }  

  </script>

  <body>

    <form onSubmit="return false;">

        <input type = "text" name="message" value="hello"/>

        <br/><br/>

        <input type="button" value="send" onClick="send(this.form.message.value)"/>

        <hr/>

        <h3>chat</h3>

        <textarea id="responseText" style="width: 800px;height: 300px;"></textarea>

    </form>

  </body>

</html>

五、结果

六、实际使用阶段、当出现3个以上客户端时回报错，io.netty.util.IllegalReferenceCountException: refCnt: 0, decrement: 1

查找资料后发现是writeAndFlush方法里面有个计数器，导致异常。解决方法：

WebSocketServerImpl不使用 private Map<ChannelId, Channel> channelMap 存放连接，使用netty提供的ChannelGroup存放连接

创建变量 private ChannelGroup group = new DefaultChannelGroup(GlobalEventExecutor.INSTANCE);

保存引用由 channelMap.put(ch.id(), ch); 改为 group.add(ch);

关闭由 channelMap.remove(future.channel().id());  改为group.remove(ch);

发送 handleFrame方法 改为

String text = ((TextWebSocketFrame) frame).text();

TextWebSocketFrame rsp = new TextWebSocketFrame(text);

group.writeAndFlush(rsp);

WebSocketServerImpl完整代码：

package com.netty;

import java.util.Map;

import java.util.concurrent.ConcurrentHashMap;

import io.netty.bootstrap.ServerBootstrap;

import io.netty.channel.Channel;

import io.netty.channel.ChannelFuture;

import io.netty.channel.ChannelFutureListener;

import io.netty.channel.ChannelHandlerContext;

import io.netty.channel.ChannelId;

import io.netty.channel.ChannelInitializer;

import io.netty.channel.ChannelPipeline;

import io.netty.channel.EventLoopGroup;

import io.netty.channel.group.ChannelGroup;

import io.netty.channel.group.DefaultChannelGroup;

import io.netty.channel.nio.NioEventLoopGroup;

import io.netty.channel.socket.nio.NioServerSocketChannel;

import io.netty.handler.codec.http.FullHttpRequest;

import io.netty.handler.codec.http.HttpHeaderNames;

import io.netty.handler.codec.http.HttpHeaders;

import io.netty.handler.codec.http.HttpMethod;

import io.netty.handler.codec.http.HttpObjectAggregator;

import io.netty.handler.codec.http.HttpServerCodec;

import io.netty.handler.codec.http.websocketx.CloseWebSocketFrame;

import io.netty.handler.codec.http.websocketx.PingWebSocketFrame;

import io.netty.handler.codec.http.websocketx.PongWebSocketFrame;

import io.netty.handler.codec.http.websocketx.TextWebSocketFrame;

import io.netty.handler.codec.http.websocketx.WebSocketFrame;

import io.netty.handler.codec.http.websocketx.WebSocketServerHandshaker;

import io.netty.handler.codec.http.websocketx.WebSocketServerHandshakerFactory;

import io.netty.handler.stream.ChunkedWriteHandler;

import io.netty.util.AttributeKey;

import io.netty.util.concurrent.GlobalEventExecutor;

public class WebSocketServerImpl implements WebSocketService, HttpService{

    private static final String HN_HTTP_CODEC = "HN_HTTP_CODEC";

    private static final String NH_HTTP_AGGREGATOR ="NH_HTTP_AGGREGATOR";

    private static final String NH_HTTP_CHUNK = "HN_HTTP_CHUNK";

    private static final String NH_SERVER = "NH_LOGIC";

    private static final AttributeKey<WebSocketServerHandshaker> ATTR_HANDSHAKER = AttributeKey.newInstance("ATTR_KEY_CHANNELID");

    private static final int MAX_CONTENT_LENGTH = ;

    private static final String WEBSOCKET_UPGRADE = "websocket";

    private static final String WEBSOCKET_CONNECTION = "Upgrade";

    private static final String WEBSOCKET_URI_ROOT_PATTERN = "ws://%s:%d";

    //地址

    private String host;

    //端口号

    private int port;

    //存放websocket连接

    private Map<ChannelId, Channel> channelMap = new ConcurrentHashMap<ChannelId, Channel>();

    private ChannelGroup group = new DefaultChannelGroup(GlobalEventExecutor.INSTANCE);

    private final String WEBSOCKET_URI_ROOT;

    public WebSocketServerImpl(String host, int port) {

        super();

        this.host = host;

        this.port = port;

        WEBSOCKET_URI_ROOT = String.format(WEBSOCKET_URI_ROOT_PATTERN, host, port);

    }

    //启动

    public void start(){

        EventLoopGroup bossGroup = new NioEventLoopGroup();

        EventLoopGroup workerGroup = new NioEventLoopGroup();

        ServerBootstrap sb = new ServerBootstrap();

        sb.group(bossGroup, workerGroup);

        sb.channel(NioServerSocketChannel.class);

        sb.childHandler(new ChannelInitializer<Channel>() {

            @Override

            protected void initChannel(Channel ch) throws Exception {

                // TODO Auto-generated method stub

                ChannelPipeline pl = ch.pipeline();

                //保存引用

                channelMap.put(ch.id(), ch);

                group.add(ch);

                ch.closeFuture().addListener(new ChannelFutureListener() {

                    @Override

                    public void operationComplete(ChannelFuture future) throws Exception {

                        // TODO Auto-generated method stub

                        //关闭后抛弃

                        channelMap.remove(future.channel().id());

                        group.remove(ch);

                    }

                });

            pl.addLast(HN_HTTP_CODEC,new HttpServerCodec());

            pl.addLast(NH_HTTP_AGGREGATOR,new HttpObjectAggregator(MAX_CONTENT_LENGTH));

            pl.addLast(NH_HTTP_CHUNK,new ChunkedWriteHandler());

            pl.addLast(NH_SERVER,new WebSocketServerHandler(WebSocketServerImpl.this,WebSocketServerImpl.this));

            }

        });

        try {

            ChannelFuture future = sb.bind(host,port).addListener(new ChannelFutureListener() {

                @Override

                public void operationComplete(ChannelFuture future) throws Exception {

                    // TODO Auto-generated method stub

                    if(future.isSuccess()){

                        System.out.println("websocket started");

                    }

                }

            }).sync();

            future.channel().closeFuture().addListener(new ChannelFutureListener() {

                @Override

                public void operationComplete(ChannelFuture future) throws Exception {

                    // TODO Auto-generated method stub

                    System.out.println("channel is closed");

                }

            }).sync();

        } catch (InterruptedException e) {

            // TODO Auto-generated catch block

            e.printStackTrace();

        } finally{

            bossGroup.shutdownGracefully();

            workerGroup.shutdownGracefully();

        }

        System.out.println("websocket shutdown");

    }

    @Override

    public void handleHttpRequset(ChannelHandlerContext ctx,

            FullHttpRequest request) {

        // TODO Auto-generated method stub

        if(isWebSocketUpgrade(request)){

            String subProtocols = request.headers().get(HttpHeaderNames.SEC_WEBSOCKET_PROTOCOL);

            WebSocketServerHandshakerFactory factory = new WebSocketServerHandshakerFactory(WEBSOCKET_URI_ROOT, subProtocols, false);

            WebSocketServerHandshaker handshaker = factory.newHandshaker(request);

            if(handshaker == null){

                WebSocketServerHandshakerFactory.sendUnsupportedVersionResponse(ctx.channel());

            }else{

                //响应请求

                handshaker.handshake(ctx.channel(), request);

                //将handshaker绑定给channel

                ctx.channel().attr(ATTR_HANDSHAKER).set(handshaker);

            }

            return;

        }

    }

    @Override

    public void handleFrame(ChannelHandlerContext ctx, WebSocketFrame frame) {

        // TODO Auto-generated method stub

        if(frame instanceof TextWebSocketFrame){

            String text = ((TextWebSocketFrame) frame).text();

            TextWebSocketFrame rsp = new TextWebSocketFrame(text);

//            System.out.println(channelMap.size());

//

//            for(Channel ch:channelMap.values()){

//

//

//                if (ctx.channel().equals(ch)) {

//                    continue;

//                }

//                ch.writeAndFlush(rsp);

//            }

            group.writeAndFlush(rsp);

//

        }

        //ping 回复 pong

        if(frame instanceof PingWebSocketFrame){

            ctx.channel().writeAndFlush(new PongWebSocketFrame(frame.content().retain()));

            return;

        }

        if(frame instanceof PongWebSocketFrame){

            return;

        }

        if(frame instanceof CloseWebSocketFrame){

            WebSocketServerHandshaker handshaker = ctx.channel().attr(ATTR_HANDSHAKER).get();

            if(handshaker == null){

                return;

            }

            handshaker.close(ctx.channel(), (CloseWebSocketFrame)frame.retain());

            return;

        }

    }

    //1、判断是否为get 2、判断Upgrade头 包含websocket字符串 3、Connection头 包换upgrade字符串

    private boolean isWebSocketUpgrade(FullHttpRequest request){

        HttpHeaders headers = request.headers();

        return request.method().equals(HttpMethod.GET)

                && headers.get(HttpHeaderNames.UPGRADE).contains(WEBSOCKET_UPGRADE)

                && headers.get(HttpHeaderNames.CONNECTION).contains(WEBSOCKET_CONNECTION);

    }

    public void sendMessage(String message){

        TextWebSocketFrame rsp = new TextWebSocketFrame(message);

        for(Channel ch:channelMap.values()){

            ch.writeAndFlush(rsp);

        }

    }

}

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