View Javadoc

    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 }