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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 578253 2007-09-21 20:13:14Z jochen $
52   */
53  public interface FileItem extends Serializable {
54  
55  
56      // ------------------------------- Methods from javax.activation.DataSource
57  
58  
59      /**
60       * Returns an {@link java.io.InputStream InputStream} that can be
61       * used to retrieve the contents of the file.
62       *
63       * @return An {@link java.io.InputStream InputStream} that can be
64       *         used to retrieve the contents of the file.
65       *
66       * @throws IOException if an error occurs.
67       */
68      InputStream getInputStream() throws IOException;
69  
70  
71      /**
72       * Returns the content type passed by the browser or <code>null</code> if
73       * not defined.
74       *
75       * @return The content type passed by the browser or <code>null</code> if
76       *         not defined.
77       */
78      String getContentType();
79  
80  
81      /**
82       * Returns the original filename in the client's filesystem, as provided by
83       * the browser (or other client software). In most cases, this will be the
84       * base file name, without path information. However, some clients, such as
85       * the Opera browser, do include path information.
86       *
87       * @return The original filename in the client's filesystem.
88       */
89      String getName();
90  
91  
92      // ------------------------------------------------------- FileItem methods
93  
94  
95      /**
96       * Provides a hint as to whether or not the file contents will be read
97       * from memory.
98       *
99       * @return <code>true</code> if the file contents will be read from memory;
100      *         <code>false</code> otherwise.
101      */
102     boolean isInMemory();
103 
104 
105     /**
106      * Returns the size of the file item.
107      *
108      * @return The size of the file item, in bytes.
109      */
110     long getSize();
111 
112 
113     /**
114      * Returns the contents of the file item as an array of bytes.
115      *
116      * @return The contents of the file item as an array of bytes.
117      */
118     byte[] get();
119 
120 
121     /**
122      * Returns the contents of the file item as a String, using the specified
123      * encoding.  This method uses {@link #get()} to retrieve the
124      * contents of the item.
125      *
126      * @param encoding The character encoding to use.
127      *
128      * @return The contents of the item, as a string.
129      *
130      * @throws UnsupportedEncodingException if the requested character
131      *                                      encoding is not available.
132      */
133     String getString(String encoding) throws UnsupportedEncodingException;
134 
135 
136     /**
137      * Returns the contents of the file item as a String, using the default
138      * character encoding.  This method uses {@link #get()} to retrieve the
139      * contents of the item.
140      *
141      * @return The contents of the item, as a string.
142      */
143     String getString();
144 
145 
146     /**
147      * A convenience method to write an uploaded item to disk. The client code
148      * is not concerned with whether or not the item is stored in memory, or on
149      * disk in a temporary location. They just want to write the uploaded item
150      * to a file.
151      * <p>
152      * This method is not guaranteed to succeed if called more than once for
153      * the same item. This allows a particular implementation to use, for
154      * example, file renaming, where possible, rather than copying all of the
155      * underlying data, thus gaining a significant performance benefit.
156      *
157      * @param file The <code>File</code> into which the uploaded item should
158      *             be stored.
159      *
160      * @throws Exception if an error occurs.
161      */
162     void write(File file) throws Exception;
163 
164 
165     /**
166      * Deletes the underlying storage for a file item, including deleting any
167      * associated temporary disk file. Although this storage will be deleted
168      * automatically when the <code>FileItem</code> instance is garbage
169      * collected, this method can be used to ensure that this is done at an
170      * earlier time, thus preserving system resources.
171      */
172     void delete();
173 
174 
175     /**
176      * Returns the name of the field in the multipart form corresponding to
177      * this file item.
178      *
179      * @return The name of the form field.
180      */
181     String getFieldName();
182 
183 
184     /**
185      * Sets the field name used to reference this file item.
186      *
187      * @param name The name of the form field.
188      */
189     void setFieldName(String name);
190 
191 
192     /**
193      * Determines whether or not a <code>FileItem</code> instance represents
194      * a simple form field.
195      *
196      * @return <code>true</code> if the instance represents a simple form
197      *         field; <code>false</code> if it represents an uploaded file.
198      */
199     boolean isFormField();
200 
201 
202     /**
203      * Specifies whether or not a <code>FileItem</code> instance represents
204      * a simple form field.
205      *
206      * @param state <code>true</code> if the instance represents a simple form
207      *              field; <code>false</code> if it represents an uploaded file.
208      */
209     void setFormField(boolean state);
210 
211 
212     /**
213      * Returns an {@link java.io.OutputStream OutputStream} that can
214      * be used for storing the contents of the file.
215      *
216      * @return An {@link java.io.OutputStream OutputStream} that can be used
217      *         for storing the contensts of the file.
218      *
219      * @throws IOException if an error occurs.
220      */
221     OutputStream getOutputStream() throws IOException;
222 
223 }