java 网络通信 netty websocket Hello World(基于Netty5.0)

  • 服务器端
import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.codec.http.HttpObjectAggregator;
import io.netty.handler.codec.http.HttpServerCodec;
import io.netty.handler.stream.ChunkedWriteHandler;

public class WebSocketServer {
    
    public void run(int port){
        EventLoopGroup bossGroup = new NioEventLoopGroup();
        EventLoopGroup workerGroup = new NioEventLoopGroup();
        try {
            ServerBootstrap b = new ServerBootstrap();
            b.group(bossGroup, workerGroup)
             .channel(NioServerSocketChannel.class)
             .childHandler(new ChannelInitializer() {
                @Override
                protected void initChannel(SocketChannel ch) throws Exception {
                    //HttpServerCodec将请求和应答消息编码或解码为HTTP消息
                    //通常接收到的http是一个片段,如果想要完整接受一次请求所有数据,我们需要绑定HttpObjectAggregator
                    //然后就可以收到一个FullHttpRequest完整的请求信息了
                    //ChunkedWriteHandler 向客户端发送HTML5文件,主要用于支持浏览器和服务器进行WebSocket通信
                    //WebSocketServerHandler自定义Handler
                    ch.pipeline().addLast("http-codec", new HttpServerCodec())
                                 .addLast("aggregator", new HttpObjectAggregator(65536)) //定义缓冲大小
                                 .addLast("http-chunked", new ChunkedWriteHandler())
                                 .addLast("handler", new WebSocketServerHandler());
                }
            });
            
            ChannelFuture f = b.bind(port).sync();
            System.out.println("start...");
            f.channel().closeFuture().sync();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            workerGroup.shutdownGracefully();
            bossGroup.shutdownGracefully();
        }
    }
    
    public static void main(String[] args) {
        new WebSocketServer().run(7777);
    }
}
  • 服务器端处理器
import java.util.logging.Level;
import java.util.logging.Logger;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.handler.codec.http.DefaultFullHttpResponse;
import io.netty.handler.codec.http.FullHttpRequest;
import io.netty.handler.codec.http.FullHttpResponse;
import io.netty.handler.codec.http.HttpHeaderUtil;
import io.netty.handler.codec.http.HttpResponseStatus;
import io.netty.handler.codec.http.HttpVersion;
import io.netty.handler.codec.http.websocketx.CloseWebSocketFrame;
import io.netty.handler.codec.http.websocketx.PingWebSocketFrame;
import io.netty.handler.codec.http.websocketx.PongWebSocketFrame;
import io.netty.handler.codec.http.websocketx.TextWebSocketFrame;
import io.netty.handler.codec.http.websocketx.WebSocketFrame;
import io.netty.handler.codec.http.websocketx.WebSocketServerHandshaker;
import io.netty.handler.codec.http.websocketx.WebSocketServerHandshakerFactory;
import io.netty.util.CharsetUtil;

public class WebSocketServerHandler extends SimpleChannelInboundHandler{

    /**
     * 日志
     */
    private static final Logger logger = 
            Logger.getLogger(WebSocketServerHandler.class.getName());
    /**
     * 全局websocket
     */
    private WebSocketServerHandshaker handshaker;
    
    @Override
    protected void messageReceived(ChannelHandlerContext ctx, Object msg)
            throws Exception {
        //普通HTTP接入
        if(msg instanceof FullHttpRequest){
            handleHttpRequest(ctx, (FullHttpRequest) msg);
        }else if(msg instanceof WebSocketFrame){ //websocket帧类型 已连接
            //BinaryWebSocketFrame CloseWebSocketFrame ContinuationWebSocketFrame 
            //PingWebSocketFrame PongWebSocketFrame TextWebScoketFrame
            handleWebSocketFrame(ctx, (WebSocketFrame) msg);
        }
    }
    
    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
        ctx.flush();
    }
    
    private void handleHttpRequest(ChannelHandlerContext ctx, FullHttpRequest request){
        //如果http解码失败 则返回http异常 并且判断消息头有没有包含Upgrade字段(协议升级)
        if(!request.decoderResult().isSuccess() 
                || (!"websocket".equals( request.headers().get("Upgrade")))    ){
            sendHttpResponse(ctx, request, new DefaultFullHttpResponse(
                    HttpVersion.HTTP_1_1, HttpResponseStatus.BAD_REQUEST));
            return ;
        }
        //构造握手响应返回
        WebSocketServerHandshakerFactory ws = new WebSocketServerHandshakerFactory("", null, false);
        handshaker = ws.newHandshaker(request);
        if(handshaker == null){
            //版本不支持
            WebSocketServerHandshakerFactory.sendUnsupportedVersionResponse(ctx.channel());
        }else{
            handshaker.handshake(ctx.channel(), request);
        }
    }
    /**
     * websocket帧
     * @param ctx
     * @param frame
     */
    private void handleWebSocketFrame(ChannelHandlerContext ctx, WebSocketFrame frame){
        //判断是否关闭链路指令
        if(frame instanceof CloseWebSocketFrame){
            handshaker.close(ctx.channel(), (CloseWebSocketFrame) frame.retain());
            return ;
        }
        //判断是否Ping消息 -- ping/pong心跳包
        if(frame instanceof PingWebSocketFrame){
            ctx.channel().write(new PongWebSocketFrame(frame.content().retain()));
            return ;
        }
        //本程序仅支持文本消息, 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 text文本帧
        String request = ((TextWebSocketFrame) frame).text();
        //打印日志
        if(logger.isLoggable(Level.FINE)){
            logger.fine(String.format("%s received %s", ctx.channel(), request));
        }
        //发送到客户端websocket
        ctx.channel().write(new TextWebSocketFrame(request 
                + ", 欢迎使用Netty WebSocket服务, 现在时刻:" 
                + new java.util.Date().toString()));
    }
    
    /**
     * response
     * @param ctx
     * @param request
     * @param response
     */
    private static void sendHttpResponse(ChannelHandlerContext ctx, 
            FullHttpRequest request, FullHttpResponse response){
        //返回给客户端
        if(response.status().code() != HttpResponseStatus.OK.code()){
            ByteBuf buf = Unpooled.copiedBuffer(response.status().toString(), CharsetUtil.UTF_8);
            response.content().writeBytes(buf);
            buf.release();
            HttpHeaderUtil.setContentLength(response, response.content().readableBytes());
        }
        //如果不是keepalive那么就关闭连接
        ChannelFuture f = ctx.channel().writeAndFlush(response);
        if(!HttpHeaderUtil.isKeepAlive(response) 
                || response.status().code() != HttpResponseStatus.OK.code()){
            f.addListener(ChannelFutureListener.CLOSE);
        }
    }
    
    /**
     * 异常 出错
     */
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause)
            throws Exception {
        cause.printStackTrace();
        ctx.close();
    }
}
 
 
  • 前端页面

    
        
        Netty websocket 时间服务器
    
    
        


服务器返回信息

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