通过先预分配一定的内存空间，再快速接受UDP数据，最后才保存到文件中。该方式避免接受数据写入文件带来的延迟，导致丢包。-Through the pre allocation of a certain memory space, and then quickly accept the UDP data, and finally saved to the file. This method avoids the delay caused by the data written to the file