    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017package org.apache.commons.fileupload;
    018
    019import java.io.File;
    020import java.io.IOException;
    021import java.io.InputStream;
    022import java.io.OutputStream;
    023import java.io.UnsupportedEncodingException;
    024
    025/**
    026 * <p> This class represents a file or form item that was received within a
    027 * {@code multipart/form-data} POST request.
    028 *
    029 * <p> After retrieving an instance of this class from a {@link
    030 * org.apache.commons.fileupload.FileUpload FileUpload} instance (see
    031 * {@link org.apache.commons.fileupload.servlet.ServletFileUpload
    032 * #parseRequest(javax.servlet.http.HttpServletRequest)}), you may
    033 * either request all contents of the file at once using {@link #get()} or
    034 * request an {@link java.io.InputStream InputStream} with
    035 * {@link #getInputStream()} and process the file without attempting to load
    036 * it into memory, which may come handy with large files.
    037 *
    038 * <p> While this interface does not extend
    039 * {@code javax.activation.DataSource} per se (to avoid a seldom used
    040 * dependency), several of the defined methods are specifically defined with
    041 * the same signatures as methods in that interface. This allows an
    042 * implementation of this interface to also implement
    043 * {@code javax.activation.DataSource} with minimal additional work.
    044 *
    045 * @since 1.3 additionally implements FileItemHeadersSupport
    046 */
    047public interface FileItem extends FileItemHeadersSupport {
    048
    049    /**
    050     * Deletes the underlying storage for a file item, including deleting any
    051     * associated temporary disk file. Although this storage will be deleted
    052     * automatically when the {@code FileItem} instance is garbage
    053     * collected, this method can be used to ensure that this is done at an
    054     * earlier time, thus preserving system resources.
    055     */
    056    void delete();
    057
    058    /**
    059     * Returns the contents of the file item as an array of bytes.
    060     *
    061     * @return The contents of the file item as an array of bytes.
    062     */
    063    byte[] get();
    064
    065    /**
    066     * Returns the content type passed by the browser or {@code null} if
    067     * not defined.
    068     *
    069     * @return The content type passed by the browser or {@code null} if
    070     *         not defined.
    071     */
    072    String getContentType();
    073
    074    /**
    075     * Returns the name of the field in the multipart form corresponding to
    076     * this file item.
    077     *
    078     * @return The name of the form field.
    079     */
    080    String getFieldName();
    081
    082    /**
    083     * Returns an {@link java.io.InputStream InputStream} that can be
    084     * used to retrieve the contents of the file.
    085     *
    086     * @return An {@link java.io.InputStream InputStream} that can be
    087     *         used to retrieve the contents of the file.
    088     *
    089     * @throws IOException if an error occurs.
    090     */
    091    InputStream getInputStream() throws IOException;
    092
    093    /**
    094     * Returns the original file name in the client's file system, as provided by
    095     * the browser (or other client software). In most cases, this will be the
    096     * base file name, without path information. However, some clients, such as
    097     * the Opera browser, do include path information.
    098     *
    099     * @return The original file name in the client's file system.
    100     * @throws InvalidFileNameException The file name contains a NUL character,
    101     *   which might be an indicator of a security attack. If you intend to
    102     *   use the file name anyways, catch the exception and use
    103     *   InvalidFileNameException#getName().
    104     */
    105    String getName();
    106
    107    /**
    108     * Returns an {@link java.io.OutputStream OutputStream} that can
    109     * be used for storing the contents of the file.
    110     *
    111     * @return An {@link java.io.OutputStream OutputStream} that can be used
    112     *         for storing the contents of the file.
    113     *
    114     * @throws IOException if an error occurs.
    115     */
    116    OutputStream getOutputStream() throws IOException;
    117
    118    /**
    119     * Returns the size of the file item.
    120     *
    121     * @return The size of the file item, in bytes.
    122     */
    123    long getSize();
    124
    125    /**
    126     * Returns the contents of the file item as a String, using the default
    127     * character encoding.  This method uses {@link #get()} to retrieve the
    128     * contents of the item.
    129     *
    130     * @return The contents of the item, as a string.
    131     */
    132    String getString();
    133
    134    /**
    135     * Returns the contents of the file item as a String, using the specified
    136     * encoding.  This method uses {@link #get()} to retrieve the
    137     * contents of the item.
    138     *
    139     * @param encoding The character encoding to use.
    140     * @return The contents of the item, as a string.
    141     * @throws UnsupportedEncodingException if the requested character
    142     *                                      encoding is not available.
    143     */
    144    String getString(String encoding) throws UnsupportedEncodingException;
    145
    146    /**
    147     * Determines whether or not a {@code FileItem} instance represents
    148     * a simple form field.
    149     *
    150     * @return {@code true} if the instance represents a simple form
    151     *         field; {@code false} if it represents an uploaded file.
    152     */
    153    boolean isFormField();
    154
    155    /**
    156     * Provides a hint as to whether or not the file contents will be read
    157     * from memory.
    158     *
    159     * @return {@code true} if the file contents will be read from memory;
    160     *         {@code false} otherwise.
    161     */
    162    boolean isInMemory();
    163
    164    /**
    165     * Sets the field name used to reference this file item.
    166     *
    167     * @param name The name of the form field.
    168     */
    169    void setFieldName(String name);
    170
    171    /**
    172     * Specifies whether or not a {@code FileItem} instance represents
    173     * a simple form field.
    174     *
    175     * @param state {@code true} if the instance represents a simple form
    176     *              field; {@code false} if it represents an uploaded file.
    177     */
    178    void setFormField(boolean state);
    179
    180    /**
    181     * A convenience method to write an uploaded item to disk. The client code
    182     * is not concerned with whether or not the item is stored in memory, or on
    183     * disk in a temporary location. They just want to write the uploaded item
    184     * to a file.
    185     * <p>
    186     * This method is not guaranteed to succeed if called more than once for
    187     * the same item. This allows a particular implementation to use, for
    188     * example, file renaming, where possible, rather than copying all of the
    189     * underlying data, thus gaining a significant performance benefit.
    190     *
    191     * @param file The {@code File} into which the uploaded item should
    192     *             be stored.
    193     *
    194     * @throws Exception if an error occurs.
    195     */
    196    void write(File file) throws Exception;
    197
    198}