Android 串口通信编程及串口协议分析

/** 
   * 读取终端设备数据 
   * @author Administrator 
   */ 
  private class ReadThread extends Thread { 
 
    @Override 
    public void run() { 
      super.run(); 
 
      // 定义一个包的最大长度 
      int maxLength = 2048; 
      byte[] buffer = new byte[maxLength]; 
      // 每次收到实际长度 
      int available = 0; 
      // 当前已经收到包的总长度 
      int currentLength = 0; 
      // 协议头长度4个字节（开始符1，类型1，长度2） 
      int headerLength = 4; 
 
      while (!isInterrupted()) { 
        try { 
          available = mInputStream.available(); 
          if (available > 0) { 
            // 防止超出数组最大长度导致溢出 
            if (available > maxLength - currentLength) { 
              available = maxLength - currentLength; 
            } 
            mInputStream.read(buffer, currentLength, available); 
            currentLength += available; 
          } 
           
        } 
        catch (Exception e) { 
          e.printStackTrace(); 
        } 
 
        int cursor = 0; 
        // 如果当前收到包大于头的长度，则解析当前包 
        while (currentLength >= headerLength) { 
          // 取到头部第一个字节 
          if (buffer[cursor] != 0x0F) { 
            --currentLength; 
            ++cursor; 
            continue; 
          } 
           
          int contentLenght = parseLen(buffer, cursor, headerLength); 
          // 如果内容包的长度大于最大内容长度或者小于等于0，则说明这个包有问题，丢弃 
          if (contentLenght <= 0 || contentLenght > maxLength - 5) { 
            currentLength = 0; 
            break; 
          } 
          // 如果当前获取到长度小于整个包的长度，则跳出循环等待继续接收数据 
          int factPackLen = contentLenght + 5; 
          if (currentLength < contentLenght + 5) { 
            break; 
          } 
 
          // 一个完整包即产生 
          // proceOnePacket(buffer,i,factPackLen); 
          onDataReceived(buffer, cursor, factPackLen); 
          currentLength -= factPackLen; 
          cursor += factPackLen;  
        } 
        // 残留字节移到缓冲区首 
        if (currentLength > 0 && cursor > 0) { 
          System.arraycopy(buffer, cursor, buffer, 0, currentLength); 
        } 
      } 
    } 
  } 
 
  /** 
   * 获取协议内容长度 
   * @param header 
   * @return 
   */ 
  public int parseLen(byte buffer[], int index, int headerLength) { 
 
//   if (buffer.length - index < headerLength) { return 0; } 
    byte a = buffer[index + 2]; 
    byte b = buffer[index + 3]; 
    int rlt = 0; 
    if (((a >> 7) & 0x1) == 0x1) { 
      rlt = (((a & 0x7f) << 8) | b); 
    } 
    else { 
      char[] tmp = new char[2]; 
      tmp[0] = (char) a; 
      tmp[1] = (char) b; 
      String s = new String(tmp, 0, 2); 
      rlt = Integer.parseInt(s, 16); 
    } 
 
    return rlt; 
  } 
 
protected void onDataReceived(final byte[] buffer, final int index, final int packlen) { 
    System.out.println("收到信息"); 
    byte[] buf = new byte[packlen]; 
    System.arraycopy(buffer, index, buf, 0, packlen); 
    ProtocolAnalyze.getInstance(myHandler).analyze(buf);  
  }