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.Serializable;
024import java.io.UnsupportedEncodingException;
025
026/**
027 * <p> This class represents a file or form item that was received within a
028 * <code>multipart/form-data</code> POST request.
029 *
030 * <p> After retrieving an instance of this class from a {@link
031 * org.apache.commons.fileupload.FileUpload FileUpload} instance (see
032 * {@link org.apache.commons.fileupload.servlet.ServletFileUpload
033 * #parseRequest(javax.servlet.http.HttpServletRequest)}), you may
034 * either request all contents of the file at once using {@link #get()} or
035 * request an {@link java.io.InputStream InputStream} with
036 * {@link #getInputStream()} and process the file without attempting to load
037 * it into memory, which may come handy with large files.
038 *
039 * <p> While this interface does not extend
040 * <code>javax.activation.DataSource</code> per se (to avoid a seldom used
041 * dependency), several of the defined methods are specifically defined with
042 * the same signatures as methods in that interface. This allows an
043 * implementation of this interface to also implement
044 * <code>javax.activation.DataSource</code> with minimal additional work.
045 *
046 * @version $Id: FileItem.java 1454690 2013-03-09 12:08:48Z simonetripodi $
047 * @since 1.3 additionally implements FileItemHeadersSupport
048 */
049public interface FileItem extends Serializable, FileItemHeadersSupport {
050
051    // ------------------------------- Methods from javax.activation.DataSource
052
053    /**
054     * Returns an {@link java.io.InputStream InputStream} that can be
055     * used to retrieve the contents of the file.
056     *
057     * @return An {@link java.io.InputStream InputStream} that can be
058     *         used to retrieve the contents of the file.
059     *
060     * @throws IOException if an error occurs.
061     */
062    InputStream getInputStream() throws IOException;
063
064    /**
065     * Returns the content type passed by the browser or <code>null</code> if
066     * not defined.
067     *
068     * @return The content type passed by the browser or <code>null</code> if
069     *         not defined.
070     */
071    String getContentType();
072
073    /**
074     * Returns the original filename in the client's filesystem, as provided by
075     * the browser (or other client software). In most cases, this will be the
076     * base file name, without path information. However, some clients, such as
077     * the Opera browser, do include path information.
078     *
079     * @return The original filename in the client's filesystem.
080     * @throws InvalidFileNameException The file name contains a NUL character,
081     *   which might be an indicator of a security attack. If you intend to
082     *   use the file name anyways, catch the exception and use
083     *   InvalidFileNameException#getName().
084     */
085    String getName();
086
087    // ------------------------------------------------------- FileItem methods
088
089    /**
090     * Provides a hint as to whether or not the file contents will be read
091     * from memory.
092     *
093     * @return <code>true</code> if the file contents will be read from memory;
094     *         <code>false</code> otherwise.
095     */
096    boolean isInMemory();
097
098    /**
099     * Returns the size of the file item.
100     *
101     * @return The size of the file item, in bytes.
102     */
103    long getSize();
104
105    /**
106     * Returns the contents of the file item as an array of bytes.
107     *
108     * @return The contents of the file item as an array of bytes.
109     */
110    byte[] get();
111
112    /**
113     * Returns the contents of the file item as a String, using the specified
114     * encoding.  This method uses {@link #get()} to retrieve the
115     * contents of the item.
116     *
117     * @param encoding The character encoding to use.
118     *
119     * @return The contents of the item, as a string.
120     *
121     * @throws UnsupportedEncodingException if the requested character
122     *                                      encoding is not available.
123     */
124    String getString(String encoding) throws UnsupportedEncodingException;
125
126    /**
127     * Returns the contents of the file item as a String, using the default
128     * character encoding.  This method uses {@link #get()} to retrieve the
129     * contents of the item.
130     *
131     * @return The contents of the item, as a string.
132     */
133    String getString();
134
135    /**
136     * A convenience method to write an uploaded item to disk. The client code
137     * is not concerned with whether or not the item is stored in memory, or on
138     * disk in a temporary location. They just want to write the uploaded item
139     * to a file.
140     * <p>
141     * This method is not guaranteed to succeed if called more than once for
142     * the same item. This allows a particular implementation to use, for
143     * example, file renaming, where possible, rather than copying all of the
144     * underlying data, thus gaining a significant performance benefit.
145     *
146     * @param file The <code>File</code> into which the uploaded item should
147     *             be stored.
148     *
149     * @throws Exception if an error occurs.
150     */
151    void write(File file) throws Exception;
152
153    /**
154     * Deletes the underlying storage for a file item, including deleting any
155     * associated temporary disk file. Although this storage will be deleted
156     * automatically when the <code>FileItem</code> instance is garbage
157     * collected, this method can be used to ensure that this is done at an
158     * earlier time, thus preserving system resources.
159     */
160    void delete();
161
162    /**
163     * Returns the name of the field in the multipart form corresponding to
164     * this file item.
165     *
166     * @return The name of the form field.
167     */
168    String getFieldName();
169
170    /**
171     * Sets the field name used to reference this file item.
172     *
173     * @param name The name of the form field.
174     */
175    void setFieldName(String name);
176
177    /**
178     * Determines whether or not a <code>FileItem</code> instance represents
179     * a simple form field.
180     *
181     * @return <code>true</code> if the instance represents a simple form
182     *         field; <code>false</code> if it represents an uploaded file.
183     */
184    boolean isFormField();
185
186    /**
187     * Specifies whether or not a <code>FileItem</code> instance represents
188     * a simple form field.
189     *
190     * @param state <code>true</code> if the instance represents a simple form
191     *              field; <code>false</code> if it represents an uploaded file.
192     */
193    void setFormField(boolean state);
194
195    /**
196     * Returns an {@link java.io.OutputStream OutputStream} that can
197     * be used for storing the contents of the file.
198     *
199     * @return An {@link java.io.OutputStream OutputStream} that can be used
200     *         for storing the contensts of the file.
201     *
202     * @throws IOException if an error occurs.
203     */
204    OutputStream getOutputStream() throws IOException;
205
206}