001// Copyright 2007, 2008 The Apache Software Foundation
002//
003// Licensed under the Apache License, Version 2.0 (the "License");
004// you may not use this file except in compliance with the License.
005// You may obtain a copy of the License at
006//
007//     http://www.apache.org/licenses/LICENSE-2.0
008//
009// Unless required by applicable law or agreed to in writing, software
010// distributed under the License is distributed on an "AS IS" BASIS,
011// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012// See the License for the specific language governing permissions and
013// limitations under the License.
014
015package org.apache.tapestry5.upload.services;
016
017import org.apache.commons.fileupload.FileUploadException;
018
019import javax.servlet.http.HttpServletRequest;
020
021/**
022 * Responsible for detecting and processing file upload requests, using Jakarta Commons FileUpload. Implementations of
023 * this service typically use the threaded service lifecycle model.
024 */
025public interface MultipartDecoder
026{
027
028    /**
029     * @param parameterName Name of the query parameter associated with the uploaded file
030     * @return a file upload with the given name, or null if no such file upload was in the request.
031     */
032    UploadedFile getFileUpload(String parameterName);
033
034    /**
035     * Decodes the request, returning a new {@link javax.servlet.http.HttpServletRequest} implementation that will allow
036     * access to the form fields submitted in the request (but omits uploaded files).
037     *
038     * @param request The incoming servlet request
039     * @return decoded http request
040     */
041    HttpServletRequest decode(HttpServletRequest request);
042
043    /**
044     * Returns the exception the occured during the file upload, or null if the processing of the multipart upload
045     * stream was succesful.
046     */
047    FileUploadException getUploadException();
048}