Netty学习笔记二

public class XDecoder extends ByteToMessageDecoder {

    //包的长度
  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();
    //判断当前包含几个数据包
    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));
    }

    //如果有多余的报文则存起来
    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));
    }
  }
}

@Override
public final ChannelPipeline addLast(EventExecutorGroup executor, ChannelHandler... handlers) {
    if (handlers == null) {
        throw new NullPointerException("handlers");
    }
    for (ChannelHandler h: handlers) {
        if (h == null) {
            break;
        }
        addLast(executor, null, h);
    }

    return this;
}

 @Override
    public final ChannelPipeline addLast(EventExecutorGroup group, String name, ChannelHandler handler) {
        final AbstractChannelHandlerContext newCtx;
        synchronized (this) { //进行了方法同步，是线程安全的体现
        //判断该handler是否以及添加过了
            checkMultiplicity(handler);

//创建一个新的AbstractChannelHandlerContext
            newCtx = newContext(group, filterName(name, handler), handler);

//将当前的Context添加到AbstractChannelHandlerContext链表尾部
            addLast0(newCtx);

            // If the registered is false it means that the channel was not registered on an eventLoop yet.
            // In this case we add the context to the pipeline and add a task that will call
            // ChannelHandler.handlerAdded(...) once the channel is registered.
            if (!registered) {
                newCtx.setAddPending();
                callHandlerCallbackLater(newCtx, true);
                return this;
            }

            EventExecutor executor = newCtx.executor();
            if (!executor.inEventLoop()) {
                callHandlerAddedInEventLoop(newCtx, executor);
                return this;
            }
        }
        callHandlerAdded0(newCtx);
        return this;
    }