code: public static String[] extractKeywords(String text)
      {
          List<Term> termList = NotionalTokenizer.segment(text);
          String[] wordArray = new String[termList.size()];
          Iterator<Term> iterator = termList.iterator();
          for (int i = 0; i < wordArray.length; i++)
          {
              wordArray[i] = iterator.next().word;
          }
          return wordArray;
      }
docs: 提取关键词，在真实的应用场景中，还应该涉及到短语
  
  @param text
  @return