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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    *
9    *      http://www.apache.org/licenses/LICENSE-2.0
10   *
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  package org.apache.commons.fileupload;
18  
19  import java.io.File;
20  import java.io.IOException;
21  import java.io.InputStream;
22  import java.io.OutputStream;
23  import java.io.Serializable;
24  import java.io.UnsupportedEncodingException;
25  
26  /**
27   * <p> This class represents a file or form item that was received within a
28   * <code>multipart/form-data</code> POST request.
29   *
30   * <p> After retrieving an instance of this class from a {@link
31   * org.apache.commons.fileupload.FileUpload FileUpload} instance (see
32   * {@link org.apache.commons.fileupload.FileUpload
33   * #parseRequest(javax.servlet.http.HttpServletRequest)}), you may
34   * either request all contents of the file at once using {@link #get()} or
35   * request an {@link java.io.InputStream InputStream} with
36   * {@link #getInputStream()} and process the file without attempting to load
37   * it into memory, which may come handy with large files.
38   *
39   * <p> While this interface does not extend
40   * <code>javax.activation.DataSource</code> per se (to avoid a seldom used
41   * dependency), several of the defined methods are specifically defined with
42   * the same signatures as methods in that interface. This allows an
43   * implementation of this interface to also implement
44   * <code>javax.activation.DataSource</code> with minimal additional work.
45   *
46   * @author <a href="mailto:Rafal.Krzewski@e-point.pl">Rafal Krzewski</a>
47   * @author <a href="mailto:sean@informage.net">Sean Legassick</a>
48   * @author <a href="mailto:jvanzyl@apache.org">Jason van Zyl</a>
49   * @author <a href="mailto:martinc@apache.org">Martin Cooper</a>
50   *
51   * @version $Id: FileItem.java 479262 2006-11-26 03:09:24Z niallp $
52   */
53  public interface FileItem
54      extends Serializable {
55  
56  
57      // ------------------------------- Methods from javax.activation.DataSource
58  
59  
60      /**
61       * Returns an {@link java.io.InputStream InputStream} that can be
62       * used to retrieve the contents of the file.
63       *
64       * @return An {@link java.io.InputStream InputStream} that can be
65       *         used to retrieve the contents of the file.
66       *
67       * @throws IOException if an error occurs.
68       */
69      InputStream getInputStream()
70          throws IOException;
71  
72  
73      /**
74       * Returns the content type passed by the browser or <code>null</code> if
75       * not defined.
76       *
77       * @return The content type passed by the browser or <code>null</code> if
78       *         not defined.
79       */
80      String getContentType();
81  
82  
83      /**
84       * Returns the original filename in the client's filesystem, as provided by
85       * the browser (or other client software). In most cases, this will be the
86       * base file name, without path information. However, some clients, such as
87       * the Opera browser, do include path information.
88       *
89       * @return The original filename in the client's filesystem.
90       */
91      String getName();
92  
93  
94      // ------------------------------------------------------- FileItem methods
95  
96  
97      /**
98       * Provides a hint as to whether or not the file contents will be read
99       * from memory.
100      *
101      * @return <code>true</code> if the file contents will be read from memory;
102      *         <code>false</code> otherwise.
103      */
104     boolean isInMemory();
105 
106 
107     /**
108      * Returns the size of the file item.
109      *
110      * @return The size of the file item, in bytes.
111      */
112     long getSize();
113 
114 
115     /**
116      * Returns the contents of the file item as an array of bytes.
117      *
118      * @return The contents of the file item as an array of bytes.
119      */
120     byte[] get();
121 
122 
123     /**
124      * Returns the contents of the file item as a String, using the specified
125      * encoding.  This method uses {@link #get()} to retrieve the
126      * contents of the item.
127      *
128      * @param encoding The character encoding to use.
129      *
130      * @return The contents of the item, as a string.
131      *
132      * @throws UnsupportedEncodingException if the requested character
133      *                                      encoding is not available.
134      */
135     String getString(String encoding)
136         throws UnsupportedEncodingException;
137 
138 
139     /**
140      * Returns the contents of the file item as a String, using the default
141      * character encoding.  This method uses {@link #get()} to retrieve the
142      * contents of the item.
143      *
144      * @return The contents of the item, as a string.
145      */
146     String getString();
147 
148 
149     /**
150      * A convenience method to write an uploaded item to disk. The client code
151      * is not concerned with whether or not the item is stored in memory, or on
152      * disk in a temporary location. They just want to write the uploaded item
153      * to a file.
154      * <p>
155      * This method is not guaranteed to succeed if called more than once for
156      * the same item. This allows a particular implementation to use, for
157      * example, file renaming, where possible, rather than copying all of the
158      * underlying data, thus gaining a significant performance benefit.
159      *
160      * @param file The <code>File</code> into which the uploaded item should
161      *             be stored.
162      *
163      * @throws Exception if an error occurs.
164      */
165     void write(File file) throws Exception;
166 
167 
168     /**
169      * Deletes the underlying storage for a file item, including deleting any
170      * associated temporary disk file. Although this storage will be deleted
171      * automatically when the <code>FileItem</code> instance is garbage
172      * collected, this method can be used to ensure that this is done at an
173      * earlier time, thus preserving system resources.
174      */
175     void delete();
176 
177 
178     /**
179      * Returns the name of the field in the multipart form corresponding to
180      * this file item.
181      *
182      * @return The name of the form field.
183      */
184     String getFieldName();
185 
186 
187     /**
188      * Sets the field name used to reference this file item.
189      *
190      * @param name The name of the form field.
191      */
192     void setFieldName(String name);
193 
194 
195     /**
196      * Determines whether or not a <code>FileItem</code> instance represents
197      * a simple form field.
198      *
199      * @return <code>true</code> if the instance represents a simple form
200      *         field; <code>false</code> if it represents an uploaded file.
201      */
202     boolean isFormField();
203 
204 
205     /**
206      * Specifies whether or not a <code>FileItem</code> instance represents
207      * a simple form field.
208      *
209      * @param state <code>true</code> if the instance represents a simple form
210      *              field; <code>false</code> if it represents an uploaded file.
211      */
212     void setFormField(boolean state);
213 
214 
215     /**
216      * Returns an {@link java.io.OutputStream OutputStream} that can
217      * be used for storing the contents of the file.
218      *
219      * @return An {@link java.io.OutputStream OutputStream} that can be used
220      *         for storing the contensts of the file.
221      *
222      * @throws IOException if an error occurs.
223      */
224     OutputStream getOutputStream() throws IOException;
225 
226 }