利用netty实现websocket ；redis的订阅发布websocket相结合

复制代码

由于Http协议是无状态的，每一次请求只能响应一次，下次请求需要重新连接。
如果客户端请求一个服务端资源，需要实时监服务端执行状态（比如导出大数据量时需要前端监控导出状态），这个时候不断请求连接浪费资源。可以通过WebSocket建立一个长连接，实现客户端与服务端双向交流。

websocket服务器

java 复制代码

public class NioWebSocketServer {
    private final Logger logger=Logger.getLogger(this.getClass());
    private void init(){
        logger.info("正在启动websocket服务器");
        NioEventLoopGroup boss=new NioEventLoopGroup();
        NioEventLoopGroup work=new NioEventLoopGroup();
        try {
            ServerBootstrap bootstrap=new ServerBootstrap();
            bootstrap.group(boss,work);
            bootstrap.channel(NioServerSocketChannel.class);
            bootstrap.childHandler(new NioWebSocketChannelInitializer());
            Channel channel = bootstrap.bind(8083).sync().channel();
            logger.info("webSocket服务器启动成功："+channel);
            channel.closeFuture().sync();
        } catch (InterruptedException e) {
            e.printStackTrace();
            logger.info("运行出错："+e);
        }finally {
            boss.shutdownGracefully();
            work.shutdownGracefully();
            logger.info("websocket服务器已关闭");
        }
    }

    public static void main(String[] args) {
        new NioWebSocketServer().init();
    }
}

ChannelInitializer

java 复制代码

import io.netty.channel.ChannelInitializer;
import io.netty.channel.socket.SocketChannel;
import io.netty.handler.codec.http.HttpObjectAggregator;
import io.netty.handler.codec.http.HttpServerCodec;
import io.netty.handler.logging.LoggingHandler;
import io.netty.handler.stream.ChunkedWriteHandler;

public class NioWebSocketChannelInitializer extends ChannelInitializer<SocketChannel> {
    @Override
    protected void initChannel(SocketChannel ch) {
        ch.pipeline().addLast("logging",new LoggingHandler("DEBUG"));//设置log监听器，并且日志级别为debug，方便观察运行流程
        ch.pipeline().addLast("http-codec",new HttpServerCodec());//设置解码器
        ch.pipeline().addLast("aggregator",new HttpObjectAggregator(65536));//聚合器，使用websocket会用到
        ch.pipeline().addLast("http-chunked",new ChunkedWriteHandler());//用于大数据的分区传输
        ch.pipeline().addLast("handler",new NioWebSocketHandler());//自定义的业务handler
    }
}

Hander

java 复制代码

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.*;
import io.netty.handler.codec.http.DefaultFullHttpResponse;
import io.netty.handler.codec.http.FullHttpRequest;
import io.netty.handler.codec.http.HttpResponseStatus;
import io.netty.handler.codec.http.HttpVersion;
import io.netty.handler.codec.http.websocketx.*;
import io.netty.util.CharsetUtil;
import org.apache.log4j.Logger;
import org.wisdom.netty.global.ChannelSupervise;

import java.util.Date;

import static io.netty.handler.codec.http.HttpUtil.isKeepAlive;

public class NioWebSocketHandler extends SimpleChannelInboundHandler<Object> {

    private final Logger logger=Logger.getLogger(this.getClass());

    private WebSocketServerHandshaker handshaker;

    /**
     重写channelRead0方法，处理接收到的消息
     * @param ctx
     * @param msg
     * @throws Exception
     */
    @Override
    protected void channelRead0(ChannelHandlerContext ctx, Object msg) throws Exception {
        logger.debug("收到消息："+msg);
        if (msg instanceof FullHttpRequest){
            //以http请求形式接入，但是走的是websocket
                handleHttpRequest(ctx, (FullHttpRequest) msg);
        }else if (msg instanceof  WebSocketFrame){
            //处理websocket客户端的消息
            handlerWebSocketFrame(ctx, (WebSocketFrame) msg);
        }
    }

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        //添加连接
        logger.debug("客户端加入连接："+ctx.channel());
        ChannelSupervise.addChannel(ctx.channel());
    }

    @Override
    public void channelInactive(ChannelHandlerContext ctx) throws Exception {
        //断开连接
        logger.debug("客户端断开连接："+ctx.channel());
        ChannelSupervise.removeChannel(ctx.channel());
    }

    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
        ctx.flush();
    }
    private void handlerWebSocketFrame(ChannelHandlerContext ctx, WebSocketFrame frame){
        // 判断是否关闭链路的指令
        if (frame instanceof CloseWebSocketFrame) {
            handshaker.close(ctx.channel(), (CloseWebSocketFrame) frame.retain());
            return;
        }
        // 判断是否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)) {
            logger.debug("本例程仅支持文本消息，不支持二进制消息");
            throw new UnsupportedOperationException(String.format(
                    "%s frame types not supported", frame.getClass().getName()));
        }
        // 返回应答消息
        String request = ((TextWebSocketFrame) frame).text();
        logger.debug("服务端收到：" + request);
        TextWebSocketFrame tws = new TextWebSocketFrame(new Date().toString()
                + ctx.channel().id() + "：" + request);
        // 群发
        ChannelSupervise.send2All(tws);
        // 返回【谁发的发给谁】
        // ctx.channel().writeAndFlush(tws);
    }
    /**
     * 唯一的一次http请求，用于创建websocket
     * */
    private void handleHttpRequest(ChannelHandlerContext ctx,
                                   FullHttpRequest req) {
        //要求Upgrade为websocket，过滤掉get/Post
        if (!req.decoderResult().isSuccess()
                || (!"websocket".equals(req.headers().get("Upgrade")))) {
            //若不是websocket方式，则创建BAD_REQUEST的req，返回给客户端
            sendHttpResponse(ctx, req, new DefaultFullHttpResponse(
                    HttpVersion.HTTP_1_1, HttpResponseStatus.BAD_REQUEST));
            return;
        }
        WebSocketServerHandshakerFactory wsFactory = new WebSocketServerHandshakerFactory(
                "ws://localhost:8083/websocket", null, false);
        handshaker = wsFactory.newHandshaker(req);
        if (handshaker == null) {
            WebSocketServerHandshakerFactory
                    .sendUnsupportedVersionResponse(ctx.channel());
        } else {
            handshaker.handshake(ctx.channel(), req);
        }
    }
    /**
     * 拒绝不合法的请求，并返回错误信息
     * */
    private static void sendHttpResponse(ChannelHandlerContext ctx,
                                         FullHttpRequest req, DefaultFullHttpResponse res) {
        // 返回应答给客户端
        if (res.status().code() != 200) {
            ByteBuf buf = Unpooled.copiedBuffer(res.status().toString(),
                    CharsetUtil.UTF_8);
            res.content().writeBytes(buf);
            buf.release();
        }
        ChannelFuture f = ctx.channel().writeAndFlush(res);
        // 如果是非Keep-Alive，关闭连接
        if (!isKeepAlive(req) || res.status().code() != 200) {
            f.addListener(ChannelFutureListener.CLOSE);
        }
    }
}

存储信息

java 复制代码

import io.netty.channel.Channel;
import io.netty.channel.ChannelId;
import io.netty.channel.group.ChannelGroup;
import io.netty.channel.group.DefaultChannelGroup;
import io.netty.handler.codec.http.websocketx.TextWebSocketFrame;
import io.netty.util.concurrent.GlobalEventExecutor;

import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;

public class ChannelSupervise {
    private   static ChannelGroup GlobalGroup=new DefaultChannelGroup(GlobalEventExecutor.INSTANCE);
    private  static ConcurrentMap<String, ChannelId> ChannelMap=new ConcurrentHashMap();
    public  static void addChannel(Channel channel){
        /**
          channel(通道是socket的连接信息;) = [id: 0x2a5ba781, L:/127.0.0.1:8083 - R:/127.0.0.1:60663]
          ==ChannelMap=={28176dd1=28176dd1, 2a5ba781=2a5ba781}
         */
        GlobalGroup.add(channel);
        ChannelMap.put(channel.id().asShortText(),channel.id());
        System.out.println("==channel=="+channel);
        System.out.println("==ChannelMap=="+ChannelMap.toString());
    }
    public static void removeChannel(Channel channel){
        GlobalGroup.remove(channel);
        ChannelMap.remove(channel.id().asShortText());
        System.out.println("==removeChannel=="+channel);
        System.out.println("==removeChannelChannelMap=="+ChannelMap.toString());
    }
    public static  Channel findChannel(String id){
        return GlobalGroup.find(ChannelMap.get(id));
    }

    /**
     * 根据channel id 进行 群发通知
     * @param tws
     */
    public static void send2All(TextWebSocketFrame tws){
        GlobalGroup.writeAndFlush(tws);
    }
}

html

java 复制代码

<!-- index.html -->
 
<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>WebSocket Test</title>
</head>
<body>
    <h1>WebSocket Test</h1>
    <div>
        <input type="text" id="message" placeholder="Message">
        <button onclick="send()">Send</button>
    </div>
    <div id="output"></div>
    <script>
        var socket = new WebSocket("ws://localhost:8083/");
 
        socket.onopen = function(event) {
            console.log("WebSocket opened: " + event);
        };
 
        socket.onmessage = function(event) {
            console.log("WebSocket message received: " + event.data);
            var output = document.getElementById("output");
            output.innerHTML += "<p>" + event.data + "</p>";
        };
 
        socket.onclose = function(event) {
            console.log("WebSocket closed: " + event);
        };
 
        function send() {
            var message = document.getElementById("message").value;
            socket.send(message);
        }
    </script>
</body>
</html>

redis 订阅

java 复制代码

   public void sendAlarmFaultMessage(String message) {

        String newMessge= null;
        try {
            newMessge = new String(message.getBytes(RedisKeyConstant.UTF8), RedisKeyConstant.UTF8);
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }
        //redisTemplate.convertAndSend(RedisKeyConstant.REDIS_CHANNEL, newMessge);
        RedissonClient redissonClient = SpringUtil.getBean(RedissonClient.class);
        RTopic topic = redissonClient.getTopic(RedisKeyConstant.REDIS_CHANNEL_FAULT);
        topic.publish(newMessge);
        redisTemplate.opsForList().rightPush(RedisKeyConstant.REDIS_MESSAGE_FAULT, newMessge);
    }

redis发布

java 复制代码

@Bean
    public RTopic rFaultTopic(RedissonClient redissonClient) {
        RTopic rTopic = redissonClient.getTopic(RedisKeyConstant.REDIS_CHANNEL_FAULT);
        try{
            if(rTopic != null){
                rTopic.addListener(String.class, (channel, message) -> {
                    if (channel.toString().contains(RedisKeyConstant.REDIS_CHANNEL_FAULT)) {
                        RedisUtil.lpop(RedisKeyConstant.REDIS_MESSAGE_FAULT);
                        log.info("Channel is already fault "+message);
                        AlarmWebsocketService alarmWebsocketService = SpringUtil.getBean(AlarmWebsocketService.class);
                        alarmWebsocketService.sendAllMessage(message);
                    }
                });
            }
        }catch (Exception e){
            log.info("Error sending alarm "+ ExceptionUtils.getStackTrace(e));
        }
        return rTopic;
    }