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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.UnsupportedEncodingException;
24  
25  /**
26   * <p> This class represents a file or form item that was received within a
27   * <code>multipart/form-data</code> POST request.
28   *
29   * <p> After retrieving an instance of this class from a {@link
30   * org.apache.commons.fileupload.FileUpload FileUpload} instance (see
31   * {@link org.apache.commons.fileupload.servlet.ServletFileUpload
32   * #parseRequest(javax.servlet.http.HttpServletRequest)}), you may
33   * either request all contents of the file at once using {@link #get()} or
34   * request an {@link java.io.InputStream InputStream} with
35   * {@link #getInputStream()} and process the file without attempting to load
36   * it into memory, which may come handy with large files.
37   *
38   * <p> While this interface does not extend
39   * <code>javax.activation.DataSource</code> per se (to avoid a seldom used
40   * dependency), several of the defined methods are specifically defined with
41   * the same signatures as methods in that interface. This allows an
42   * implementation of this interface to also implement
43   * <code>javax.activation.DataSource</code> with minimal additional work.
44   *
45   * @since 1.3 additionally implements FileItemHeadersSupport
46   */
47  public interface FileItem extends FileItemHeadersSupport {
48  
49      // ------------------------------- Methods from javax.activation.DataSource
50  
51      /**
52       * Returns an {@link java.io.InputStream InputStream} that can be
53       * used to retrieve the contents of the file.
54       *
55       * @return An {@link java.io.InputStream InputStream} that can be
56       *         used to retrieve the contents of the file.
57       *
58       * @throws IOException if an error occurs.
59       */
60      InputStream getInputStream() throws IOException;
61  
62      /**
63       * Returns the content type passed by the browser or <code>null</code> if
64       * not defined.
65       *
66       * @return The content type passed by the browser or <code>null</code> if
67       *         not defined.
68       */
69      String getContentType();
70  
71      /**
72       * Returns the original filename in the client's filesystem, as provided by
73       * the browser (or other client software). In most cases, this will be the
74       * base file name, without path information. However, some clients, such as
75       * the Opera browser, do include path information.
76       *
77       * @return The original filename in the client's filesystem.
78       * @throws InvalidFileNameException The file name contains a NUL character,
79       *   which might be an indicator of a security attack. If you intend to
80       *   use the file name anyways, catch the exception and use
81       *   InvalidFileNameException#getName().
82       */
83      String getName();
84  
85      // ------------------------------------------------------- FileItem methods
86  
87      /**
88       * Provides a hint as to whether or not the file contents will be read
89       * from memory.
90       *
91       * @return <code>true</code> if the file contents will be read from memory;
92       *         <code>false</code> otherwise.
93       */
94      boolean isInMemory();
95  
96      /**
97       * Returns the size of the file item.
98       *
99       * @return The size of the file item, in bytes.
100      */
101     long getSize();
102 
103     /**
104      * Returns the contents of the file item as an array of bytes.
105      *
106      * @return The contents of the file item as an array of bytes.
107      */
108     byte[] get();
109 
110     /**
111      * Returns the contents of the file item as a String, using the specified
112      * encoding.  This method uses {@link #get()} to retrieve the
113      * contents of the item.
114      *
115      * @param encoding The character encoding to use.
116      *
117      * @return The contents of the item, as a string.
118      *
119      * @throws UnsupportedEncodingException if the requested character
120      *                                      encoding is not available.
121      */
122     String getString(String encoding) throws UnsupportedEncodingException;
123 
124     /**
125      * Returns the contents of the file item as a String, using the default
126      * character encoding.  This method uses {@link #get()} to retrieve the
127      * contents of the item.
128      *
129      * @return The contents of the item, as a string.
130      */
131     String getString();
132 
133     /**
134      * A convenience method to write an uploaded item to disk. The client code
135      * is not concerned with whether or not the item is stored in memory, or on
136      * disk in a temporary location. They just want to write the uploaded item
137      * to a file.
138      * <p>
139      * This method is not guaranteed to succeed if called more than once for
140      * the same item. This allows a particular implementation to use, for
141      * example, file renaming, where possible, rather than copying all of the
142      * underlying data, thus gaining a significant performance benefit.
143      *
144      * @param file The <code>File</code> into which the uploaded item should
145      *             be stored.
146      *
147      * @throws Exception if an error occurs.
148      */
149     void write(File file) throws Exception;
150 
151     /**
152      * Deletes the underlying storage for a file item, including deleting any
153      * associated temporary disk file. Although this storage will be deleted
154      * automatically when the <code>FileItem</code> instance is garbage
155      * collected, this method can be used to ensure that this is done at an
156      * earlier time, thus preserving system resources.
157      */
158     void delete();
159 
160     /**
161      * Returns the name of the field in the multipart form corresponding to
162      * this file item.
163      *
164      * @return The name of the form field.
165      */
166     String getFieldName();
167 
168     /**
169      * Sets the field name used to reference this file item.
170      *
171      * @param name The name of the form field.
172      */
173     void setFieldName(String name);
174 
175     /**
176      * Determines whether or not a <code>FileItem</code> instance represents
177      * a simple form field.
178      *
179      * @return <code>true</code> if the instance represents a simple form
180      *         field; <code>false</code> if it represents an uploaded file.
181      */
182     boolean isFormField();
183 
184     /**
185      * Specifies whether or not a <code>FileItem</code> instance represents
186      * a simple form field.
187      *
188      * @param state <code>true</code> if the instance represents a simple form
189      *              field; <code>false</code> if it represents an uploaded file.
190      */
191     void setFormField(boolean state);
192 
193     /**
194      * Returns an {@link java.io.OutputStream OutputStream} that can
195      * be used for storing the contents of the file.
196      *
197      * @return An {@link java.io.OutputStream OutputStream} that can be used
198      *         for storing the contensts of the file.
199      *
200      * @throws IOException if an error occurs.
201      */
202     OutputStream getOutputStream() throws IOException;
203 
204 }