public static void main(String[] args) {
        String str = "中国";
        
        System.out.println("系统默认编码：" + Charset.defaultCharset());
        
        try {
            //第一种情况
            byte[] bytes1 = str.getBytes("GBK");
            String newStr1 = new String(bytes1, "GBK");
            System.out.println(newStr1);
            
            //第二种情况
            byte[] bytes2 = str.getBytes("UTF-8");
            String newStr2 = new String(bytes2, "UTF-8");
            System.out.println(newStr2);
            
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }
    }