In a Java portlet I'm offering files to download through the serveResource(...) method.
I'm calling
response.getPortletOutputStream().write(byteArray);
This byte array contains some special characters in German, for example Ä, Ü or ö. The file format of the resulting file is csv.
When I'm opening the file in a text editor, the special characters are displayed correctly.
However when I open them in Microsoft Excel, they're displayed as ü or ß.
Do you have any ideas of what could be the cause of this problem?
Notepad++ displays the file as
ANSI as UTF-8