# FileItemStream.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;

    import java.io.IOException;
    import java.io.InputStream;

    /**
     * <p> This interface provides access to a file or form item that was
     * received within a {@code multipart/form-data} POST request.
     * The items contents are retrieved by calling {@link #openStream()}.</p>
     * <p>Instances of this class are created by accessing the
     * iterator, returned by
     * {@link FileUploadBase#getItemIterator(RequestContext)}.</p>
     * <p><em>Note</em>: There is an interaction between the iterator and
     * its associated instances of {@link FileItemStream}: By invoking
     * {@link java.util.Iterator#hasNext()} on the iterator, you discard all data,
     * which hasn't been read so far from the previous data.</p>
     */
    public interface FileItemStream extends FileItemHeadersSupport {

        /**
         * This exception is thrown, if an attempt is made to read
         * data from the {@link InputStream}, which has been returned
         * by {@link FileItemStream#openStream()}, after
         * {@link java.util.Iterator#hasNext()} has been invoked on the
         * iterator, which created the {@link FileItemStream}.
         */
        class ItemSkippedException extends IOException {

            /**
             * The exceptions serial version UID, which is being used
             * when serializing an exception instance.
             */
            private static final long serialVersionUID = -7280778431581963740L;

            /**
             * Constructs a new instance.
             */
            public ItemSkippedException() {
                // empty
            }

        }

        /**
         * Returns the content type passed by the browser or {@code null} if
         * not defined.
         *
         * @return The content type passed by the browser or {@code null} if
         *         not defined.
         */
        String getContentType();

        /**
         * Returns the name of the field in the multipart form corresponding to
         * this file item.
         *
         * @return The name of the form field.
         */
        String getFieldName();

        /**
         * Returns the original file name in the client's file system, as provided by
         * the browser (or other client software). In most cases, this will be the
         * base file name, without path information. However, some clients, such as
         * the Opera browser, do include path information.
         *
         * @return The original file name in the client's file system.
         */
        String getName();

        /**
         * Determines whether or not a {@code FileItem} instance represents
         * a simple form field.
         *
         * @return {@code true} if the instance represents a simple form
         *         field; {@code false} if it represents an uploaded file.
         */
        boolean isFormField();

        /**
         * Creates an {@link InputStream}, which allows to read the
         * items contents.
         *
         * @return The input stream, from which the items data may
         *   be read.
         * @throws IllegalStateException The method was already invoked on
         * this item. It is not possible to recreate the data stream.
         * @throws IOException An I/O error occurred.
         * @see ItemSkippedException
         */
        InputStream openStream() throws IOException;

    }