Java NIO Charset编码解码

Question

考虑以下操作顺序：

String pt = "abcd";
byte[] b64 = Base64.decodeBase64(pt.getBytes("UTF-8"));
ByteBuffer wrap = ByteBuffer.wrap(b64);
CharBuffer decode = StandardCharsets.UTF_8.decode(wrap);

ByteBuffer encode = StandardCharsets.UTF_8.encode(decode);
byte[] bytes = new byte[encode.remaining()];
encode.get(bytes);
String x = Base64.encodeBase64String(bytes); // "ae+/vR0="

为什么pt和x不相等？

我使用这些功能错了吗？发生了什么事？

Answer 1

据我所知，您希望将某些字符串编码为base64格式并将其解码为相同的字符串。

<强>代码：

public static void main(String[] args) {
  final String pt = "abcd";
  final byte[] b64 = Base64.encodeBase64(pt.getBytes(StandardCharsets.UTF_8));
  System.out.println(new String(b64, StandardCharsets.US_ASCII));


  final String x = new String(Base64.decodeBase64(b64), StandardCharsets.UTF_8);
  System.out.printf("pt: %s -- x: %s", pt, x);
}

或

public static void main(String[] args) {
  final String pt = "abcd";
  final ByteBuffer buffer = StandardCharsets.UTF_8.encode(pt);
  final byte[] base64 = Base64.encodeBase64(buffer.array());
  System.out.println(new String(base64));

  final String x = StandardCharsets.UTF_8.decode(ByteBuffer.wrap(Base64.decodeBase64(base64))).toString();
  System.out.printf("pt: %s -- x: %s", pt, x);
}

<强>结果：

YWJjZA==
pt: abcd -- x: abcd