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    
015    package org.apache.tapestry5.upload.services;
016    
017    import org.apache.commons.fileupload.FileUploadException;
018    
019    import 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     */
025    public 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    }