Encoded String

Question

Hi all
I'm having problems with decoding an encoded String. The String i have looks like this:
=?ISO-8859-1?Q?F=E4lt=F6m?=
The code I use to try and decode the string looks like this:
fileName = fileName.substring(fileName.indexOf("=?") + 2, fileName.lastIndexOf("?="));
StringTokenizer st = new StringTokenizer(fileName, "?");
String encodingType = st.nextToken();
System.out.println("Encoding type: " + encodingType);
String type = st.nextToken();
System.out.println("Type: " + type);
String name = st.nextToken();
System.out.println("Name: " + name);
try {
  String newFileName = new String(name.getBytes(encodingType), encodingType);
  System.out.println("New filename: " + newFileName);
} catch (Exception ex) {
  ex.printStackTrace();
}The output is:
Encoding type: ISO-8859-1
Type: Q
Name: F=E4lt=F6m
New filename: F=E4lt=F6m
What's wrong with my way of decoding the String?
Thanks
Tobias

Answer 1

This encoding is called "quoted printable". Writing a decoder for it is not hard -- the thing after the = sign is the two character hex code of the actual character -- but there is no built in support for it in J2SE (as there isn't out-of-the-box support for Base64 either).
There is support for it in the JavaMail-extension package though, by the class javax.mail.internet.MimeUtility. You must be doing something related to email anyway, so I would recommend having a look at it.
http://java.sun.com/products/javamail/
Quoted printable is defined at least in section 6.7 of RFC 2045:
http://faqs.org/rfcs/rfc2045.html