code: public static String canonicalize(String str, String splitRegexp,
  			String join, boolean trim, boolean excludeEmpty,
  			boolean capitalizeWord) {
  		if (str == null)
  			return null;
  
  		return join(str.split(splitRegexp), join, trim, excludeEmpty,
  				capitalizeWord);
  	}
docs: 把str按splitRegexp进行拆分后，用join作为连接拼接在一起