按网络字节序从字节数组中拿出8个字节拼装成一个long型

/**
   * 按网络字节序从字节数组中拿出8个字节拼装成一个long型(对应c++中的long long)数据
   * 
   * @param from
   * @param fromIndex
   * @return
   */
  public static long getLongLongData(byte[] from, int fromIndex) {  return (((long) from[fromIndex + 4] & 0xff) << 56)
     + (((long) from[fromIndex + 5] & 0xff) << 48)
     + (((long) from[fromIndex + 6] & 0xff) << 40)
     + (((long) from[fromIndex + 7] & 0xff) << 32)
     + (((long) from[fromIndex] & 0xff) << 24)
     + (((long) from[fromIndex + 1] & 0xff) << 16)
     + (((long) from[fromIndex + 2] & 0xff) << 8)
     + ((long) from[fromIndex + 3] & 0xff);
  }