使用java的Unicode base 64编码

Question

我正在尝试编码和解码UTF8字符串到base64.理论上不是问题,但解码时似乎永远不会输出正确的字符而是？

        String original = "?????????";
        B64encoder benco = new B64encoder();
        String enc = benco.encode(original);
        try
        {
            String dec = new String(benco.decode(enc.toCharArray()), "UTF-8");
            PrintStream out = new PrintStream(System.out, true, "UTF-8");
            out.println("Original: " + original);
            prtHx("ara", original.getBytes());
            out.println("Encoded: " + enc);
            prtHx("enc", enc.getBytes());
            out.println("Decoded: " + dec);
            prtHx("dec", dec.getBytes());
        } catch (UnsupportedEncodingException e)
        {
            e.printStackTrace();
        }

控制台的输出如下:

原文:خهعسيبنتا
ara = 3F,3F,3F,3F,3F,3F,3F,3F,3F
编码:Pz8/Pz8/Pz8/
enc = 50,7A,38,2F,50,7A,38,2F ,50, 7A,38,2F
解码:?????????
dec = 3F,3F,3F,3F,3F,3F,3F,3F,3F

prtHx只是将字节的十六进制值写入输出.我在做一些明显不对的事吗？

---

Andreas通过强调getBytes()方法使用平台默认编码(Cp1252)来指出正确的解决方案,即使源文件本身是UTF-8.通过使用getBytes("UTF-8"),我能够注意到编码和解码的字节实际上是不同的.进一步调查表明,编码方法使用了getBytes().改变这个很好地解决了这个问题.

try
        {
            String enc = benco.encode(original);
            String dec = new String(benco.decode(enc.toCharArray()), "UTF-8");
            PrintStream out = new PrintStream(System.out, true, "UTF-8");
            out.println("Original: " + original);
            prtHx("ori", original.getBytes("UTF-8"));
            out.println("Encoded: " + enc);
            prtHx("enc", enc.getBytes("UTF-8"));
            out.println("Decoded: " + dec);
            prtHx("dec", dec.getBytes("UTF-8"));

        } catch (UnsupportedEncodingException e)
        {
            e.printStackTrace();
        }

系统编码Cp1252
原文:خهعسيبنتا
ori = D8,AE,
D9,87 ,D8,B9,D8,B3,D9,8A,D8,A8, D9,86 ,D8,AA,D8,A7 编码:2K7Zh9i52LPZitio2YbYqtin
enc = 32, 4B,
37,5A,68,39,69,35,32,4C,50,5A,69,74,69,6F,32,59,62,59,71,74,69,6E解码:خهعسيبنتا
dec = D8,AE,D9,87,D8,B9,D8,B3,D9,8A,D8,A8,D9,86,D8,AA,D8,A7

谢谢.

Answer 1

String#getBytes()使用平台的默认字符集对字符进行编码.字符串文字的实际编码"?????????"在java源文件中"已定义"(您在创建或保存文件时选择字符编码)

这可能是原因,为什么ara编码为0x3f字节..

尝试一下:

out.println("Original: " + original);
prtHx("ara", original.getBytes("UTF-8"));
out.println("Encoded: " + enc);
prtHx("enc", enc.getBytes("UTF-8"));
out.println("Decoded: " + dec);
prtHx("dec", dec.getBytes("UTF-8"));