字符格式化

        String s = "ABCD中國人";
        // Byte 數組
        byte[] bytes = s.getBytes("UTF-8");
        System.out.println(bytes.length);   // 目前編碼爲utf-8 爲13字節 byte序列
        System.out.println(Arrays.toString(bytes));

        String str = new String(bytes,"UTF-8");
        System.out.println(str); // 字符串 char序列