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.t2framework.confeito.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</code> 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}.
	 */
	public static class ItemSkippedException extends IOException {
		/**
		 * The exceptions serial version UID, which is being used when
		 * serializing an exception instance.
		 */
		private static final long serialVersionUID = -7280778431581963740L;
	}

	/**
	 * 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;

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

	/**
	 * Returns the original filename in the client's filesystem, 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 filename in the client's filesystem.
	 */
	String getName();

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

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