字符格式化

        String s = "ABCD中国人";
        // Byte 数组
        byte[] bytes = s.getBytes("UTF-8");
        System.out.println(bytes.length); // 目前编码为utf-8 为13字节 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