# ServletFileUpload.java

    /*
     * Licensed to the Apache Software Foundation (ASF) under one or more
     * contributor license agreements.  See the NOTICE file distributed with
     * this work for additional information regarding copyright ownership.
     * The ASF licenses this file to You under the Apache License, Version 2.0
     * (the "License"); you may not use this file except in compliance with
     * the License.  You may obtain a copy of the License at
     *
     *      http://www.apache.org/licenses/LICENSE-2.0
     *
     * Unless required by applicable law or agreed to in writing, software
     * distributed under the License is distributed on an "AS IS" BASIS,
     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     * See the License for the specific language governing permissions and
     * limitations under the License.
     */
    package org.apache.commons.fileupload.servlet;

    import java.io.IOException;
    import java.util.List;
    import java.util.Map;

    import javax.servlet.http.HttpServletRequest;

    import org.apache.commons.fileupload.FileItem;
    import org.apache.commons.fileupload.FileItemFactory;
    import org.apache.commons.fileupload.FileItemIterator;
    import org.apache.commons.fileupload.FileUpload;
    import org.apache.commons.fileupload.FileUploadBase;
    import org.apache.commons.fileupload.FileUploadException;

    /**
     * <p>High level API for processing file uploads.</p>
     *
     * <p>This class handles multiple files per single HTML widget, sent using
     * {@code multipart/mixed} encoding type, as specified by
     * <a href="http://www.ietf.org/rfc/rfc1867.txt">RFC 1867</a>.  Use {@link
     * #parseRequest(HttpServletRequest)} to acquire a list of {@link
     * org.apache.commons.fileupload.FileItem}s associated with a given HTML
     * widget.</p>
     *
     * <p>How the data for individual parts is stored is determined by the factory
     * used to create them; a given part may be in memory, on disk, or somewhere
     * else.</p>
     */
    public class ServletFileUpload extends FileUpload {

        /**
         * Constant for HTTP POST method.
         */
        private static final String POST_METHOD = "POST";

        /**
         * Utility method that determines whether the request contains multipart
         * content.
         *
         * @param request The servlet request to be evaluated. Must be non-null.
         * @return {@code true} if the request is multipart;
         *         {@code false} otherwise.
         */
        public static final boolean isMultipartContent(
                final HttpServletRequest request) {
            if (!POST_METHOD.equalsIgnoreCase(request.getMethod())) {
                return false;
            }
            return FileUploadBase.isMultipartContent(new ServletRequestContext(request));
        }

        /**
         * Constructs an uninitialized instance of this class. A factory must be
         * configured, using {@code setFileItemFactory()}, before attempting
         * to parse requests.
         *
         * @see FileUpload#FileUpload(FileItemFactory)
         */
        public ServletFileUpload() {
        }

        /**
         * Constructs an instance of this class which uses the supplied factory to
         * create {@code FileItem} instances.
         *
         * @see FileUpload#FileUpload()
         * @param fileItemFactory The factory to use for creating file items.
         */
        public ServletFileUpload(final FileItemFactory fileItemFactory) {
            super(fileItemFactory);
        }

        /**
         * Processes an <a href="http://www.ietf.org/rfc/rfc1867.txt">RFC 1867</a>
         * compliant {@code multipart/form-data} stream.
         *
         * @param request The servlet request to be parsed.
         * @return An iterator to instances of {@code FileItemStream}
         *         parsed from the request, in the order that they were
         *         transmitted.
         *
         * @throws FileUploadException if there are problems reading/parsing
         *                             the request or storing files.
         * @throws IOException An I/O error occurred. This may be a network
         *   error while communicating with the client or a problem while
         *   storing the uploaded content.
         */
        public FileItemIterator getItemIterator(final HttpServletRequest request)
        throws FileUploadException, IOException {
            return super.getItemIterator(new ServletRequestContext(request));
        }

        /**
         * Processes an <a href="http://www.ietf.org/rfc/rfc1867.txt">RFC 1867</a>
         * compliant {@code multipart/form-data} stream.
         *
         * @param request The servlet request to be parsed.
         * @return A map of {@code FileItem} instances parsed from the request.
         * @throws FileUploadException if there are problems reading/parsing
         *                             the request or storing files.
         *
         * @since 1.3
         */
        public Map<String, List<FileItem>> parseParameterMap(final HttpServletRequest request)
                throws FileUploadException {
            return parseParameterMap(new ServletRequestContext(request));
        }

        /**
         * Processes an <a href="http://www.ietf.org/rfc/rfc1867.txt">RFC 1867</a>
         * compliant {@code multipart/form-data} stream.
         *
         * @param request The servlet request to be parsed.
         * @return A list of {@code FileItem} instances parsed from the
         *         request, in the order that they were transmitted.
         *
         * @throws FileUploadException if there are problems reading/parsing
         *                             the request or storing files.
         */
        @Override
        public List<FileItem> parseRequest(final HttpServletRequest request)
        throws FileUploadException {
            return parseRequest(new ServletRequestContext(request));
        }

    }