思路：将文件逐行读入，然后用StringTokenizer进行处理，将一个个word以（名称，出现次数）存入hashmap，依次统计如果出现多次出现次数递加，文件全部处理完后再读出，这样就算出了词频-Idea: read the file line by line, and then processed using StringTokenizer will be a word to (name, frequency) into the hashmap, followed by statistic