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Pax Wicket Service is an OSGi extension of the Wicket framework, allowing for dynamic loading and unloading of Wicket components and pageSources.

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/*
 * 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.wicket.util.upload;

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


/**
 * 
 * This interface provides access to a file or form item that was received within a
 * multipart/form-data POST request. The items contents are retrieved by calling
 * {@link #openStream()}.
 * 
 * 
 * Instances of this class are created by accessing the iterator, returned by
 * {@link FileUploadBase#getItemIterator(RequestContext)}.
 * 
 * 
 * Note: 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.
 * 
 */
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 null if not defined.
	 * 
	 * @return The content type passed by the browser or null 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 FileItem instance represents a simple form field.
	 * 
	 * @return true if the instance represents a simple form field; false
	 *         if it represents an uploaded file.
	 */
	boolean isFormField();
}