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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 }