<html:file property="theFile" accept="image/gif,application/msword,application/zip,application/pdf,image/jpeg"  />

 private   boolean  accept(String fileName) {
         if  (fileName.toLowerCase().endsWith(".txt") || fileName.toLowerCase().endsWith(".doc") ||
                fileName.toLowerCase().endsWith(".zip") || fileName.toLowerCase().endsWith(".pdf") ||
                fileName.toLowerCase().endsWith(".jpg") || fileName.toLowerCase().endsWith(".jpeg") ||
                fileName.toLowerCase().endsWith(".gif")) {
             return  true;
        }
         return  false;
    }