一个文件缓存类。每生成以缓存会同时生成以个hash加密的meta文件名cache文件名，读取缓存时首先要读取meta文件，判断缓存是否过期或者缓存文件是否存在，如果缓存文件被修改过，读取依然会失败。-A file cache class. Each generated to cache will also generate a hash encrypted meta file cache file name, read cache must first read the meta file to determine if the cache expires or cache file exists, if the cache file has been modified to read still will fail....