code: public static long bytesToLong(byte[] b)
      {
          long l = ((long) b[0] << 56) & 0xFF00000000000000L;
          // 如果不强制转换为long，那么默认会当作int，导致最高32位丢失
          l |= ((long) b[1] << 48) & 0xFF000000000000L;
          l |= ((long) b[2] << 40) & 0xFF0000000000L;
          l |= ((long) b[3] << 32) & 0xFF00000000L;
          l |= ((long) b[4] << 24) & 0xFF000000L;
          l |= ((long) b[5] << 16) & 0xFF0000L;
          l |= ((long) b[6] << 8) & 0xFF00L;
          l |= (long) b[7] & 0xFFL;
          return l;
      }
docs: 将一个8位字节数组转换为长整数。<br>
  注意，函数中不会对字节数组长度进行判断，请自行保证传入参数的正确性。
  
  @param b 字节数组
  @return 长整数