对一个文件夹下面的doc和txt文件（文件夹下不包含文件夹）中的内容建立索引并实现了搜索功能。（代码有缺陷，见谅）-On a folder below the doc and txt files (folder does not contain a folder) to index the content and the achievement of the search function. (Code are flawed, will be forgiven)