code: public static StringType getStringType(String str) {
  		TreeSet<CharType> set = getTypeSet(str);
  		if(set.size()==1){
  			CharType c = set.first();
  			return char2StringType(c);
  		}
  		return StringType.M;		
  	}
docs: 得到字符串类型
  @param str
  @return
  @see Chars#char2StringType(CharType)