Netty对WebSocket的支持

一、创建服务端代码

1、MyServer 类

public class MyServer {
    public static void main(String[] args) throws  Exception{
        EventLoopGroup bossGroup = new NioEventLoopGroup();
        EventLoopGroup workerGroup = new NioEventLoopGroup();
        try{

            ServerBootstrap serverBootstrap = new ServerBootstrap();
            serverBootstrap.group(bossGroup,workerGroup).channel(NioServerSocketChannel.class)
                    .handler(new LoggingHandler(LogLevel.INFO)) //增加日志处理器
                    .childHandler(new WebSocketChannelInitializer());

            ChannelFuture channelFuture = serverBootstrap.bind(new InetSocketAddress(8899)).sync();
            channelFuture.channel().closeFuture().sync();
        }finally {
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }
}

2、WebSocketChannelInitializer 类

public class WebSocketChannelInitializer extends ChannelInitializer<SocketChannel>{

    protected void initChannel(SocketChannel socketChannel) throws Exception {
        ChannelPipeline pipeline = socketChannel.pipeline();
        pipeline.addLast(new HttpServerCodec());
        pipeline.addLast(new ChunkedWriteHandler());
        pipeline.addLast(new HttpObjectAggregator(8192));
        pipeline.addLast(new WebSocketServerProtocolHandler("/ws"));
        pipeline.addLast(new TextWebSocketFrameHandle());
    }
}

3、TextWebSocketFrameHandle 类

public class TextWebSocketFrameHandle extends SimpleChannelInboundHandler<TextWebSocketFrame> {


    @Override
    protected void channelRead0(ChannelHandlerContext ctx, TextWebSocketFrame msg) throws Exception {
        CommonUtil.println("收到消息:" + msg.text());
        ctx.channel().writeAndFlush(new TextWebSocketFrame("服务器时间:" + LocalDateTime.now()));
    }

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

    @Override
    public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
        CommonUtil.println("handlerRemoved:" +ctx.channel().id().asLongText());
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        CommonUtil.println("异常发生");
         ctx.close();
    }
}

二、编写客户端WebSocket代码

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>WebSocket</title>
</head>
<body>
<script type="text/javascript">

    var socket;

    if(window.WebSocket){
        socket = new WebSocket("ws://localhost:8899/ws");
        socket.onmessage = function (event) {
            var ta = document.getElementById("responseText");
            ta.value = ta.value + "\n" + event.data;
        }
        socket.onopen = function (event) {
            var ta = document.getElementById("responseText");
            ta.value = "连接开启";

        }

        socket.onclose = function (event) {
            var ta = document.getElementById("responseText");
            ta.value = ta.value + "\n" + "连接关闭！";
        }

    }else {
        alert("浏览器不支持WebSocket")
    }

    function  send(message) {
        if(!window.WebSocket){
            return;
        }
        if(socket.readyState == WebSocket.OPEN){
            socket.send(message);
        }else{
            alert("连接尚未开启");
        }
    }

</script>
<form onsubmit="return false">
    <textarea name="message" style="width: 400px ; height:  200px;" ></textarea>

    <input type="button" value="发送数据" onclick="send(this.form.message.value)">

    <h3>服务端输出:</h3>

    <textarea id="responseText" style="width: 400px ; height: 300px;" ></textarea>

    <input type="button" value="清空内容" onclick="javascript: document.getElementById('responseText').value=''">
</form>
</body>
</html>

三、测试

1、启动服务端

2、打开页面 http://localhost:7080/test.html

可以看到，连接开启。

服务端输出如下图：

四、进入页面的开发者模式

可以发现，

1、Status Code:101 Switching Protocols。原来是Http的，切换成Socket

2、请求头： Upgrade:websocket

虽然请求发送的ws，但是要先发送的http请求建立连接，连接建立好后，将http升级到websockent协议上

五、测试发送消息

整个请求建立在webSocket协议之上。

Netty对WebSocket的支持

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