实现文件映射，在两个进程间共享内存，在不同进程间传输大文件时，可大幅度提升访问速度。本源码仅为模拟，共享内存为1K，可自行调整。-File mapping, in shared memory between two processes in different inter-process transfer large files, they can significantly enhance the access speed. The only source simulation, shared