Netty核心模块组件 - WebSocket - 《Java 进阶》

Server
Handler

Server

public class Server {
    public static void main(String[] args) throws InterruptedException {
        EventLoopGroup bossGroup = new NioEventLoopGroup(1);
        EventLoopGroup workerGroup = new NioEventLoopGroup();
        try {
            ServerBootstrap serverBootstrap = new ServerBootstrap();
            serverBootstrap.group(bossGroup, workerGroup)
                    .channel(NioServerSocketChannel.class)
                    .handler(new LoggingHandler(LogLevel.INFO))
                    .childHandler(new ChannelInitializer<SocketChannel>() {
                        @Override
                        protected void initChannel(SocketChannel ch) throws Exception {
                            ChannelPipeline pipeline = ch.pipeline();
                            //使用Http的编解码器
                            pipeline.addLast(new HttpServerCodec());
                            //以块方式写，添加ChunkedWriteHandler处理器
                            pipeline.addLast(new ChunkedWriteHandler());
                            /*
                            1.Http协议在传输过程中是分段的，HttpObjectAggregator就是可以将多个段聚合
                            2.这就是为什么当浏览器发送大量数据时，就会发出多次http请求的原因
                             */
                            pipeline.addLast(new HttpObjectAggregator(8192));
                            /*
                            1.对应WebSocket，它的数据是以帧(frame)的形式传递
                            2.可以看到WEbSocketFrame 下面有六个子类
                            WebSocketServerProtocolHandler作用：
                            3.浏览器发送请求时 ws://localhost:7000/hello--识别请求的资源
                            4.将一个Http协议升级为WS协议，即WebSocket协议--保存长连接
                             */
                            pipeline.addLast(new WebSocketServerProtocolHandler("/hello"));
                            //自定义handler，处理业务逻辑
                            pipeline.addLast(new TextWebSocketFrameHandler());
                        }
                    });
            ChannelFuture future = serverBootstrap.bind(7000).sync();
            future.channel().closeFuture().sync();
        } finally {
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }
}

Handler

//TextWebSocketFrame表示一个文本帧(frame)
public class TextWebSocketFrameHandler extends SimpleChannelInboundHandler<TextWebSocketFrame> {
    @Override
    protected void channelRead0(ChannelHandlerContext ctx, TextWebSocketFrame msg) throws Exception {
        System.out.println("服务器收到消息" + msg.text());
        //回复消息
        ctx.channel().writeAndFlush(new TextWebSocketFrame("服务器时间" + LocalDateTime.now() + "" + msg.text()));
    }
    //感知连接
    @Override
    public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
        //id是一个唯一的值， LongText是唯一的
        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());
    }
    //感知断开连接
    @Override
    public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
        System.out.println("handlerRemoved被调用" + ctx.channel().id().asLongText());
    }
    //异常
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        System.out.println(cause.getMessage());
        ctx.close(); //关闭连接
    }
}

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<!--复制到Vscode-->
<body>
<script>
    var socket;
    //判断当前浏览器是否支持websocket
    if(window.WebSocket) {
        //go on
        socket = new WebSocket("ws://localhost:7000/hello");
        //相当于channelReado, 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(感知到连接开启)
        socket.onopen = function (ev) {
            var rt = document.getElementById("responseText");
            rt.value = "连接开启了.."
        }
        //相当于连接关闭(感知到连接关闭)
        socket.onclose = function (ev) {
            var rt = document.getElementById("responseText");
            rt.value = rt.value + "\n" + "连接关闭了.."
        }
    } else {
        alert("当前浏览器不支持websocket")
    }
    //发送消息到服务器
    function send(message) {
        if(!window.socket) { //先判断socket是否创建好
            return;
        }
        if(socket.readyState == WebSocket.OPEN) {
            //通过socket 发送消息
            socket.send(message)
        } else {
            alert("连接没有开启");
        }
    }
</script>
<form onsubmit="return false">
    <textarea name="message" style="height: 300px; width: 300px"></textarea>
    <input type="button" value="发送消息" onclick="send(this.form.message.value)">
    <textarea id="responseText" style="height: 300px; width: 300px"></textarea>
    <input type="button" value="清空内容" onclick="document.getElementById('responseText').value=''">
</form>
</body>
</html>