您需要指定所需的编码，例如对于UTF-8

You need to specify the encoding you want e.g. for UTF-8

String doc = ....
byte[] bytes = doc.getBytes("UTF-8");
String doc2 = new String(bytes, "UTF-8");

doc 和 doc2 将是相同的。

要解码 byte [] ，你需要知道使用了什么编码来确保它能正确解码。

To decode a byte[] you need to know what encoding was used to be sure it will decode correctly.