java 中取出unicode字符串中的不可見字符

my_string.replaceAll("\\p{C}", "?");

        BufferedReader reader = new BufferedReader(new FileReader(
                "D:\\test\\1.txt"));
        String stopWord = null;
        while ((stopWord = reader.readLine()) != null) {
            stopWord=stopWord.replaceAll("\\p{C}", "");
            System.out.println(stopWord);
            char[] test = stopWord.toCharArray();
            for (char c : test) {
                System.out.println(c);
                
            }
        }

http://stackoverflow.com/questions/6198986/how-can-i-replace-non-printable-unicode-characters-in-java