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 */
017 package org.apache.commons.fileupload;
018
019 import java.io.File;
020 import java.io.IOException;
021 import java.io.InputStream;
022 import java.io.OutputStream;
023 import java.io.Serializable;
024 import 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 */
049 public 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 }