/* * 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.File;import java.io.IOException;import java.io.InputStream;import java.io.OutputStream;import java.io.Serializable;import java.io.UnsupportedEncodingException;/** * <p> This class represents a file or form item that was received within a * <code>multipart/form-data</code> POST request. * * <p> After retrieving an instance of this class from a {@link * org.apache.commons.fileupload.FileUpload FileUpload} instance (see * {@link org.apache.commons.fileupload.FileUpload * #parseRequest(javax.servlet.http.HttpServletRequest)}), you may * either request all contents of the file at once using {@link #get()} or * request an {@link java.io.InputStream InputStream} with * {@link #getInputStream()} and process the file without attempting to load * it into memory, which may come handy with large files. * * <p> While this interface does not extend * <code>javax.activation.DataSource</code> per se (to avoid a seldom used * dependency), several of the defined methods are specifically defined with * the same signatures as methods in that interface. This allows an * implementation of this interface to also implement * <code>javax.activation.DataSource</code> with minimal additional work. * * @author <a href="mailto:Rafal.Krzewski@e-point.pl">Rafal Krzewski</a> * @author <a href="mailto:sean@informage.net">Sean Legassick</a> * @author <a href="mailto:jvanzyl@apache.org">Jason van Zyl</a> * @author <a href="mailto:martinc@apache.org">Martin Cooper</a> * * @version $Id: FileItem.java 479262 2006-11-26 03:09:24Z niallp $ */public interface FileItem    extends Serializable {    // ------------------------------- Methods from javax.activation.DataSource    /**     * Returns an {@link java.io.InputStream InputStream} that can be     * used to retrieve the contents of the file.     *     * @return An {@link java.io.InputStream InputStream} that can be     *         used to retrieve the contents of the file.     *     * @throws IOException if an error occurs.     */    InputStream getInputStream()        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();    // ------------------------------------------------------- FileItem methods    /**     * Provides a hint as to whether or not the file contents will be read     * from memory.     *     * @return <code>true</code> if the file contents will be read from memory;     *         <code>false</code> otherwise.     */    boolean isInMemory();    /**     * Returns the size of the file item.     *     * @return The size of the file item, in bytes.     */    long getSize();    /**     * Returns the contents of the file item as an array of bytes.     *     * @return The contents of the file item as an array of bytes.     */    byte[] get();    /**     * Returns the contents of the file item as a String, using the specified     * encoding.  This method uses {@link #get()} to retrieve the     * contents of the item.     *     * @param encoding The character encoding to use.     *     * @return The contents of the item, as a string.     *     * @throws UnsupportedEncodingException if the requested character     *                                      encoding is not available.     */    String getString(String encoding)        throws UnsupportedEncodingException;    /**     * Returns the contents of the file item as a String, using the default     * character encoding.  This method uses {@link #get()} to retrieve the     * contents of the item.     *     * @return The contents of the item, as a string.     */    String getString();    /**     * A convenience method to write an uploaded item to disk. The client code     * is not concerned with whether or not the item is stored in memory, or on     * disk in a temporary location. They just want to write the uploaded item     * to a file.     * <p>     * This method is not guaranteed to succeed if called more than once for     * the same item. This allows a particular implementation to use, for     * example, file renaming, where possible, rather than copying all of the     * underlying data, thus gaining a significant performance benefit.     *     * @param file The <code>File</code> into which the uploaded item should     *             be stored.     *     * @throws Exception if an error occurs.     */    void write(File file) throws Exception;    /**     * Deletes the underlying storage for a file item, including deleting any     * associated temporary disk file. Although this storage will be deleted     * automatically when the <code>FileItem</code> instance is garbage     * collected, this method can be used to ensure that this is done at an     * earlier time, thus preserving system resources.     */    void delete();    /**     * Returns the name of the field in the multipart form corresponding to     * this file item.     *     * @return The name of the form field.     */    String getFieldName();    /**     * Sets the field name used to reference this file item.     *     * @param name The name of the form field.     */    void setFieldName(String name);    /**     * 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();    /**     * Specifies whether or not a <code>FileItem</code> instance represents     * a simple form field.     *     * @param state <code>true</code> if the instance represents a simple form     *              field; <code>false</code> if it represents an uploaded file.     */    void setFormField(boolean state);    /**     * Returns an {@link java.io.OutputStream OutputStream} that can     * be used for storing the contents of the file.     *     * @return An {@link java.io.OutputStream OutputStream} that can be used     *         for storing the contensts of the file.     *     * @throws IOException if an error occurs.     */    OutputStream getOutputStream() throws IOException;}