用Netty4.x+WebSocket制作简单的聊天系统

版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/jingyangV587/article/details/79869993

创建Server 服务端

添加依赖的包

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

创建一个WebSocketServer类

这里主要绑定一个端口的操作

public class WebSocketServer {
    public void run(int port) throws Exception {
        EventLoopGroup bossGroup = new NioEventLoopGroup();
        EventLoopGroup workerGroup = new NioEventLoopGroup();
        try {
            ServerBootstrap b = new ServerBootstrap();
            b.group(bossGroup, workerGroup).channel(NioServerSocketChannel.class).childHandler(new ChannelInitializer<SocketChannel>() {
                        @Override
                        protected void initChannel(SocketChannel ch) throws Exception {
                            ChannelPipeline pipeline = ch.pipeline();
                            pipeline.addLast("http-codec", new HttpServerCodec());
                            pipeline.addLast("aggregator", new HttpObjectAggregator(65536));
                            ch.pipeline().addLast("http-chunked", new ChunkedWriteHandler());
                            pipeline.addLast("handler", new WebSocketServerHandler());
                        }
                    });

            Channel ch = b.bind(port).sync().channel();
            System.out.println("Web socket server started at port " + port + '.');
            System.out.println("Open your browser and navigate to http://localhost:" + port + '/');

            ch.closeFuture().sync();
        } finally {
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }

    public static void main(String[] args) throws Exception {
        int port = 8088;
        if (args.length > 0) {
            try {
                port = Integer.parseInt(args[0]);
            } catch (NumberFormatException e) {
                e.printStackTrace();
            }
        }
        new WebSocketServer().run(port);
    }
}

创建一个WebSocketServerHandler类

这里是主要写自己业务逻辑的地方

public class WebSocketServerHandler extends SimpleChannelInboundHandler<Object> {
    private static final Logger logger = Logger.getLogger(WebSocketServerHandler.class.getName());
    public static ChannelGroup channels = new DefaultChannelGroup(GlobalEventExecutor.INSTANCE);
    private WebSocketServerHandshaker handshaker;

    @Override
    public void channelRead0(ChannelHandlerContext ctx, Object msg) throws Exception {
        // 传统的HTTP接入
        if (msg instanceof FullHttpRequest) {
            handleHttpRequest(ctx, (FullHttpRequest) msg);
        }
        // WebSocket接入
        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 {

        // 如果HTTP解码失败，返回HHTP异常
        if (!req.decoderResult().isSuccess() || (!"websocket".equals(req.headers().get("Upgrade")))) {
            sendHttpResponse(ctx, req, new DefaultFullHttpResponse(HTTP_1_1, BAD_REQUEST));
            return;
        }

        // 构造握手响应返回，本机测试
        WebSocketServerHandshakerFactory wsFactory = new WebSocketServerHandshakerFactory("ws://localhost:8088/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 frame) {

        // 判断是否是关闭链路的指令
        if (frame instanceof CloseWebSocketFrame) {
            handshaker.close(ctx.channel(), (CloseWebSocketFrame) frame.retain());
            return;
        }
        // 判断是否是Ping消息
        if (frame instanceof PingWebSocketFrame) {
            ctx.channel().write(new PongWebSocketFrame(frame.content().retain()));
            return;
        }
        // 本例程仅支持文本消息，不支持二进制消息
        if (!(frame instanceof TextWebSocketFrame)) {
            throw new UnsupportedOperationException(
                    String.format("%s frame types not supported", frame.getClass().getName()));
        }

        // 返回应答消息
        String request = ((TextWebSocketFrame) frame).text();
        if (logger.isLoggable(Level.FINE)) {
            logger.fine(String.format("%s received %s", ctx.channel(), request));
        }

        //currentUserChannel为当前会话通道
        Channel currentUserChannel = ctx.channel();
        for (Channel channel : channels) {
           if (channel != currentUserChannel){
                channel.writeAndFlush(new TextWebSocketFrame(channel.remoteAddress()+"  "+request));
            }else {
                channel.writeAndFlush(new TextWebSocketFrame("我"+"  "+request ));
            }
        }

        //ctx.channel().write(new TextWebSocketFrame(request + " , 欢迎使用Netty WebSocket服务，现在时刻：" + new java.util.Date().toString()));
    }

    private static void sendHttpResponse(ChannelHandlerContext ctx, FullHttpRequest req, FullHttpResponse res) {
        // 返回应答给客户端
        if (res.getStatus().code() != 200) {
            ByteBuf buf = Unpooled.copiedBuffer(res.getStatus().toString(), CharsetUtil.UTF_8);
            res.content().writeBytes(buf);
            buf.release();
            HttpUtil.setContentLength(res, res.content().readableBytes());
        }

        // 如果是非Keep-Alive，关闭连接
        ChannelFuture f = ctx.channel().writeAndFlush(res);
        if (!HttpUtil.isKeepAlive(req) || res.status().code() != 200) {
            f.addListener(ChannelFutureListener.CLOSE);
        }
    }

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

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception { // (5)
        channels.add(ctx.channel());
    }

    @Override
    public void channelInactive(ChannelHandlerContext ctx) throws Exception { // (6)
        channels.remove(ctx.channel());
    }
}

运行WebSocketServer类中的main方法

这时netty服务已经启动了

测试

用websocket连接服务器进行测试

测试的HTML代码如下：

<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    Netty WebSocket 时间服务器
</head>
<br>
<body>
<br>
<script type="text/javascript">
    var socket;
    if (!window.WebSocket) {
        window.WebSocket = window.MozWebSocket;
    }
    if (window.WebSocket) {
        socket = new WebSocket("ws://localhost:8088/websocket");
        socket.onmessage = function (event) {
            var ta = document.getElementById('responseText');
            //ta.value = ""; 
            ta.value =ta.value +"\n"+ event.data 
        }; 
        socket.onopen = function (event) {
            var ta = document.getElementById('responseText');
            ta.value = "打开WebSocket服务正常，浏览器支持WebSocket!";
        };
        socket.onclose = function (event) { 
            var ta = document.getElementById('responseText'); 
            ta.value = "";
            ta.value = "WebSocket 关闭!";
        };
    }
    else {
        alert("抱歉，您的浏览器不支持WebSocket协议!");
    }

    function send(message) {
        if (!window.WebSocket) {
            return;
        }
        if (socket.readyState == WebSocket.OPEN) {
            socket.send(message); 
        }
        else {
            alert("WebSocket连接没有建立成功!");
        }
    }
</script>
<form onsubmit="return false;">
    <input type="text" name="message"/>
    <br><br>
    <input type="button" value="发送WebSocket请求消息" onclick="send(this.form.message.value)"/>
    <hr color="blue"/>
    <h3>服务端返回的应答消息</h3>
    <textarea id="responseText" style="width:500px;height:300px;"></textarea>
</form>
</body>
</html>

运行结果截图：

项目地址：https://gitee.com/jingyang3877/netty-demo

参考博客：
https://www.cnblogs.com/carl10086/p/6188808.html
http://wiki.jikexueyuan.com/project/netty-4-user-guide/implement-websocket-chat-function.html
https://blog.csdn.net/shudaqi2010/article/details/54293000