服务端

public class Server {
    private final int port;

    public Server(int port) {
        this.port = port;
    }

    public void run() {
        //创建两个事件循环组，bossGroup只处理连接请求，workGroup处理客户端业务处理，交给bossGroup
        //两个都是无线循环
        //默认CPU核*2
        EventLoopGroup bossGroup = new NioEventLoopGroup();
        EventLoopGroup workGroup = new NioEventLoopGroup();

        try {
            //创建服务端启动对象，配置参数
            ServerBootstrap bootstrap = new ServerBootstrap();

            //用链式编程进行设置
            bootstrap.group(bossGroup, workGroup)//设置两个线程组
                    .channel(NioServerSocketChannel.class)//使用NioSocketChannel作为服务器通道实现
                    //.option(ChannelOption.SO_BACKLOG, 128)//设置线程队列个数
                    //.childOption(ChannelOption.SO_KEEPALIVE, true)//设置保持活动连接状态
                    .handler(new LoggingHandler(LogLevel.INFO))
                    .childHandler(new ChannelInitializer<SocketChannel>() {
                        @Override
                        protected void initChannel(SocketChannel channel) throws Exception {
                            ChannelPipeline pipeline = channel.pipeline();
                            //http编码与解码器
                            pipeline.addLast(new HttpServerCodec())
                                    //以块方式写
                                    .addLast(new ChunkedWriteHandler())
                                    //http在传输中是分段的，HttpObjectAggregator可以将多个分段聚合起来
                                    //当浏览器发送大量数据时，会发出多次http请求
                                    .addLast(new HttpObjectAggregator(8192))
                                    //对于websocket，它的数据时以帧（frame）形式传递
                                    //可以看到webSocketFrame下面有六个子类
                                    //浏览器请求时是webSocket所以是ws开头的，如ws://localhost:666/hello，与如下WebSocketServerProtocolHandler对应
                                    //WebSocketServerProtocolHandler核心功能是将http协议升级为ws协议，保持长连接
                                    .addLast(new WebSocketServerProtocolHandler("/hello"))
                                    //自定义handler，处理业务逻辑
                                    .addLast(new ServerHandler());
                        }
                    });//给workGroup的EventLoop对应的管道设置处理器

            //启动服务器，绑定端口，生成ChannelFuture对象
            ChannelFuture future = bootstrap.bind(port).sync();
            //对关闭通道进行监听(非阻塞监听，异步模型)
            future.channel().closeFuture().sync();
        } catch (InterruptedException e) {
            e.printStackTrace();
        } finally {
            bossGroup.shutdownGracefully();
            workGroup.shutdownGracefully();
        }
    }

    public static void main(String[] args) throws InterruptedException {
        new Server(666).run();
    }
}

服务端Handler

//SimpleChannelInboundHandler继承HandlerAdapter
//TextWebSocketFrame表示一个文本帧（frame）
public class ServerHandler extends SimpleChannelInboundHandler<TextWebSocketFrame> {
    @Override
    protected void channelRead0(ChannelHandlerContext ctx, TextWebSocketFrame msg) throws Exception {
        System.out.println("服务端收到消息" + msg.text());
        //回复消息
        ctx.channel().writeAndFlush(new TextWebSocketFrame("服务器时间" + LocalDateTime.now() + msg.text()));
    }

    //建立连接，触发此事件
    @Override
    public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
        //LongText唯一的
        System.out.println("handlerAdded被调用" + ctx.channel().id().asLongText());
        //ShortText不是唯一的
        System.out.println("handlerAdded被调用" + ctx.channel().id().asShortText());
    }

    //断开连接，触发此事件，将离开信息推送给在线客户
    @Override
    public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
        System.out.println("handlerRemoved被调用" + ctx.channel().id().asLongText());
    }

    //处理异常，关闭通道
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        cause.printStackTrace();
        ctx.close();
    }
}

HTML页面

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>hello</title>
</head>
<body>
<script>
    var socket;
    //判断浏览器是否支持websocket
    if (window.WebSocket) {
        socket = new WebSocket("ws://localhost:666/hello");
        //相当于channelRead0，ev收到服务器端回送的消息
        socket.onmessage = function (ev) {
            var rt = document.getElementById("responseText");
            rt.value = rt.value + "\n" + ev.data;
        }
        //相当于连接开启
        socket.onopen = function (ev) {
            var rt = document.getElementById("responseText");
            rt.value = "连接开启了...";
        }
        //感觉到连接关闭
        socket.onclose = function (ev) {
            var rt = document.getElementById("responseText");
            rt.value = rt.value + "\n" + "连接关闭了...";
        }
    } else {
        alert("浏览器不支持WebSocket")
    }

    function send(msg) {
        //判断socket是否创建好
        if (!window.socket) {
            return;
        }
        if (socket.readyState == WebSocket.OPEN) {
            //通过socket发送消息
            socket.send(msg)
        } else {
            alert("连接没有开启")
        }
    }
</script>
<form onsubmit="return false">
    <textarea name="message" style="width: 200px;height: 100px;"></textarea>
    <input type="button" value="发送" onclick="send(this.form.message.value)">
    <textarea id="responseText" style="width: 200px;height: 100px;"></textarea>
    <input type="button" value="清空" onclick="document.getElementById('responseText').value=''">
</form>
</body>
</html>

效果

Netty websocket长连接_bootstrap

Netty websocket长连接_websocket_02