JAVA Netty TCP 粘包/半包解决 以及遇到的问题（实现断线重连）

在使用netty 实现tcp时，出现数据大量的粘包和半包的情况，在需要准确的数据下做以下处理

  private Bootstrap createBootstrap(Bootstrap bootstrap, EventLoopGroup eventLoop) {
        if (bootstrap != null) {
            final MyInboundHandler handler = new MyInboundHandler(this);
            bootstrap.group(eventLoop);
            bootstrap.channel(NioSocketChannel.class);
            bootstrap.option(ChannelOption.SO_KEEPALIVE, true);
            bootstrap.handler(new ChannelInitializer<SocketChannel>() {
                        @Override
                        protected void initChannel(SocketChannel socketChannel) {
                            //解决粘包和半包问题 接收数据全部要以/r/n分割
                            socketChannel.pipeline().addLast(new LineBasedFrameDecoder(1024));
                            socketChannel.pipeline().addLast(new StringDecoder());
                            socketChannel.pipeline().addLast(handler);
                            socketChannel.pipeline().addLast(new OutBoundHandler());
                        }
                    }).remoteAddress(ip, port);
            bootstrap.connect().addListener(new ConnectionListener(this));
        }
        return bootstrap;
    }

 这里是利用netty自带的编译规则

//解决粘包和半包问题 接收数据全部要以/r/n分割
                            socketChannel.pipeline().addLast(new LineBasedFrameDecoder(1024));
                            socketChannel.pipeline().addLast(new StringDecoder());

注意这里实现原理是利用n  或者rn 分割数据，将上一次的数据若不全和下一次组合在一起成为完整数据，若发送的数据没有特殊符号则在接收里面无法接收到数据，最后附上TCP完整使用：

  public synchronized void start() {
        createBootstrap(new Bootstrap(), loop);
    }

    private Bootstrap createBootstrap(Bootstrap bootstrap, EventLoopGroup eventLoop) {
        if (bootstrap != null) {
            final MyInboundHandler handler = new MyInboundHandler(this);
            bootstrap.group(eventLoop);
            bootstrap.channel(NioSocketChannel.class);
            bootstrap.option(ChannelOption.SO_KEEPALIVE, true);
            bootstrap.handler(new ChannelInitializer<SocketChannel>() {
                        @Override
                        protected void initChannel(SocketChannel socketChannel) {
                            //解决粘包和半包问题 接收数据全部要以/r/n分割
                            socketChannel.pipeline().addLast(new LineBasedFrameDecoder(1024));
                            socketChannel.pipeline().addLast(new StringDecoder());
                            socketChannel.pipeline().addLast(handler);
                            socketChannel.pipeline().addLast(new OutBoundHandler());
                        }
                    }).remoteAddress(ip, port);
            bootstrap.connect().addListener(new ConnectionListener(this));
        }
        return bootstrap;
    }

    /**
     * 向服务器发送消息
     *
     * @param msg
     * @throws Exception
     */
    public boolean sendMsg(Object msg) throws Exception {
        byte[] bytes = msg.toString().getBytes();
        if (channel == null) {
            return false;
        }
        if (!channel.isActive()) {
            return false;
        }
        channel.writeAndFlush(bytes);
        return true;
    }

    /**
     * 发送消息给服务器
     * @param msg 消息
     */
    public boolean sendMsg(byte[] msg) {

        if (channel == null) {
            return false;
        }
        if (!channel.isActive()) {
            return false;
        }
        channel.writeAndFlush(msg);
        return true;
    }


    @AllArgsConstructor
    class  MyInboundHandler extends ChannelInboundHandlerAdapter {

        private MessageClient messageClient;

        /**
         * 断开连接时的回调 断线重连
         * @param ctx
         * @throws Exception
         */
        @Override
        public void channelInactive(ChannelHandlerContext ctx) throws Exception {
            log.info("Message channel inactive:" + ctx.channel().remoteAddress());
            channel = null;
            final EventLoop eventLoop = ctx.channel().eventLoop();
            eventLoop.schedule(() -> {
                messageClient.createBootstrap(new Bootstrap(), eventLoop);
            }, 2L, TimeUnit.SECONDS);
            super.channelInactive(ctx);
        }

        /**
         * 建立连接时的回调
         * @param ctx
         * @throws Exception
         */
        @Override
        public void channelActive(ChannelHandlerContext ctx) throws Exception {
            log.info("Message channel active:" + ctx.channel().remoteAddress());
            channel = ctx.channel();
            
            } catch (Exception e) {
                e.printStackTrace();
            }
            super.channelActive(ctx);
        }

        /**
         * 接收到数据时调用
         * @param ctx
         * @param msg
         */
        @Override
        public  void channelRead(ChannelHandlerContext ctx, Object  msg) {
                String msg1 = (String) msg;   
         }

    @AllArgsConstructor
    class ConnectionListener implements ChannelFutureListener {

        private MessageClient messageClient;

        @Override
        public void operationComplete(ChannelFuture channelFuture) {
            if (!channelFuture.isSuccess()) {
                log.info("restart");
                final EventLoop loop = channelFuture.channel().eventLoop();
                loop.schedule(() -> {
                    messageClient.createBootstrap(new Bootstrap(), loop);
                }, 2L, TimeUnit.SECONDS);
            } else {
                log.info("message server started! port:" + port);
            }
        }
    }

    private class OutBoundHandler extends ChannelOutboundHandlerAdapter {
        @Override
        public void write(ChannelHandlerContext ctx, Object msg, ChannelPromise promise) {
            if (msg instanceof byte[]) {
                byte[] bytesWrite = (byte[])msg;
                System.out.println(new String(bytesWrite));
                ByteBuf buf = ctx.alloc().buffer(bytesWrite.length);
                buf.writeBytes(bytesWrite);

                ctx.writeAndFlush(buf).addListener((ChannelFutureListener) channelFuture -> System.out.println("send option success!"));
            }
        }
    }

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