Rewrite Upload Binary File Into A Normal File

I upload a file and save it like the following  

byte[] uploadedFileBuf = new byte[(int) uploadedFile.length()];
saveFileSystem(excelUpload + getLocalFileName(acad_year, stuid), uploadedFileBuf);
private boolean saveFileSystem(String filename, byte[] data){
  try{
        FileOutputStream fos = new FileOutputStream(filename);
          fos.write(data);
         fos.close();

[Code]...

I can not read it  use

HSSFWorkbook WorkBook = new HSSFWorkbook(new FileInputStream(filename));