以文件的形式保存数据，能够自动记录位置，即使重新开始程序也能找到之前存储和读取的位置；能够自动删除过期文件，文件中的数据以一条条记录存储，类似队列。最终提供的接口只有存入和读取函数，使用简单。-Save data in the form of a document that can automatically record the location, even if the re-start before the program can find the location of storage and retrieval　to automatically delete the expired file, the file data to a record store, similar to the queue. Ultimately provide the interface function is only stored and read, simple to use.