Netty中粘包和拆包的解决方案

// Server主程序
public class XNettyServer {
  public static void main(String[] args) throws Exception {

    // accept 处理连接的线程池
    NioEventLoopGroup acceptGroup = new NioEventLoopGroup();

    // read io 处理数据的线程池
    NioEventLoopGroup readGroup = new NioEventLoopGroup();

    try {
      ServerBootstrap serverBootstrap = new ServerBootstrap();
      serverBootstrap
          .group(acceptGroup, readGroup)
          .channel(NioServerSocketChannel.class)
          .childHandler(
              new ChannelInitializer<SocketChannel>() {
                @Override
                protected void initChannel(SocketChannel ch) throws Exception {
                  ChannelPipeline pipeline = ch.pipeline();

                  // 增加解码器
                  pipeline.addLast(new XDecoder());

                  // 打印出内容 handdler
                  pipeline.addLast(new XHandler());
                }
              });
      System.out.println("启动成功，端口 7777");
      serverBootstrap.bind(7777).sync().channel().closeFuture().sync();
    } finally {
      acceptGroup.shutdownGracefully();
      readGroup.shutdownGracefully();
    }
  }

}

// 解码器
public class XDecoder extends ByteToMessageDecoder {

  static final int PACKET_SIZE = 220;

  // 用来临时保留没有处理过的请求报文
  ByteBuf tempMsg = Unpooled.buffer();

  /**
   * @param ctx
   * @param in 请求的数据
   * @param out 将粘在一起的报文拆分后的结果保留起来
   * @throws Exception
   */
  @Override
  protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception {
    System.out.println(Thread.currentThread() + "收到了一次数据包，长度是：" + in.readableBytes());

    // 合并报文
    ByteBuf message = null;

    int tmpMsgSize = tempMsg.readableBytes();

    // 如果暂存有上一次余下的请求报文，则合并
    if (tmpMsgSize > 0) {
      message = Unpooled.buffer();
      message.writeBytes(tempMsg);
      message.writeBytes(in);
      System.out.println("合并：上一数据包余下的长度为：" + tmpMsgSize + ",合并后长度为:" + message.readableBytes());
    } else {
      message = in;
    }
    int size = message.readableBytes();
    int counter = size / PACKET_SIZE;
    for (int i = 0; i < counter; i++) {
      byte[] request = new byte[PACKET_SIZE];
      // 每次从总的消息中读取220个字节的数据
      message.readBytes(request);
      // 将拆分后的结果放入out列表中，交由后面的业务逻辑去处理
      out.add(Unpooled.copiedBuffer(request));

    }

    // 多余的报文存起来
    // 第一个报文：i+  暂存
    // 第二个报文：1 与第一次
    size = message.readableBytes();

    if (size != 0) {
      System.out.println("多余的数据长度：" + size);
      // 剩下来的数据放到tempMsg暂存
      tempMsg.clear();
      tempMsg.writeBytes(message.readBytes(size));
    }
  }

}

// 处理器
public class XHandler extends ChannelInboundHandlerAdapter {

  @Override
  public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
    ctx.flush();
  }
  @Override
  public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
    ByteBuf byteBuf = (ByteBuf) msg;
    byte[] content = new byte[byteBuf.readableBytes()];
    byteBuf.readBytes(content);
    System.out.println(Thread.currentThread() + ": 最终打印" + new String(content));
    ((ByteBuf) msg).release();
  }
  @Override
  public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
    cause.printStackTrace();
    ctx.close();
  }

}