code: public String replaceSensitiveWord(String txt,MatchType matchType,String replaceChar){
  		String resultTxt = txt;
  		Set<String> set = findSensitiveWord(txt, matchType);     //获取所有的敏感词
  		Iterator<String> iterator = set.iterator();
  		String word = null;
  		String replaceString = null;
  		while (iterator.hasNext()) {
  			word = iterator.next();
  			replaceString = getReplaceChars(replaceChar, word.length());
  			resultTxt = resultTxt.replaceAll(word, replaceString);
  		}
  		
  		return resultTxt;
  	}
docs: 替换敏感字字符
  @param txt
  @param matchType
  @param replaceChar 替换字符，默认*
  @version 1.0