001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.commons.fileupload2.core;
018
019import java.io.IOException;
020import java.io.InputStream;
021import java.io.OutputStream;
022import java.nio.charset.Charset;
023import java.nio.file.InvalidPathException;
024import java.nio.file.Path;
025
026/**
027 * <p>
028 * This class represents a file or form item that was received within a {@code multipart/form-data} POST request.
029 * </p>
030 * <p>
031 * After retrieving an instance of this class from a {@link AbstractFileUpload FileUpload} instance (see
032 * {@code org.apache.commons.fileupload2.core.servlet.ServletFileUpload #parseRequest(javax.servlet.http.HttpServletRequest)}), you may either request all
033 * contents of the file at once using {@link #get()} or request an {@link InputStream} with {@link #getInputStream()} and process the file without attempting to
034 * load it into memory, which may come handy with large files.
035 * </p>
036 * <p>
037 * While this interface does not extend {@code javax.activation.DataSource} (to avoid a seldom used dependency), several of the defined methods are specifically
038 * defined with the same signatures as methods in that interface. This allows an implementation of this interface to also implement
039 * {@code javax.activation.DataSource} with minimal additional work.
040 * </p>
041 *
042 * @param <F> The FileItem type.
043 */
044public interface FileItem<F extends FileItem<F>> extends FileItemHeadersProvider<F> {
045
046    /**
047     * Deletes the underlying storage for a file item, including deleting any associated temporary disk file. Use this method to ensure that this is done at an
048     * earlier time, to preserve resources.
049     *
050     * @return {@code this} instance.
051     * @throws IOException if an error occurs.
052     */
053    F delete() throws IOException;
054
055    /**
056     * Gets the contents of the file item as a byte array.
057     *
058     * @return The contents of the file item as a byte array.
059     * @throws IOException if an I/O error occurs
060     */
061    byte[] get() throws IOException;
062
063    /**
064     * Gets the content type passed by the browser or {@code null} if not defined.
065     *
066     * @return The content type passed by the browser or {@code null} if not defined.
067     */
068    String getContentType();
069
070    /**
071     * Gets the name of the field in the multipart form corresponding to this file item.
072     *
073     * @return The name of the form field.
074     */
075    String getFieldName();
076
077    /**
078     * Gets an {@link java.io.InputStream InputStream} that can be used to retrieve the contents of the file.
079     *
080     * @return An {@link java.io.InputStream InputStream} that can be used to retrieve the contents of the file.
081     * @throws IOException if an error occurs.
082     */
083    InputStream getInputStream() throws IOException;
084
085    /**
086     * Gets the original file name in the client's file system, as provided by the browser (or other client software). In most cases, this will be the base file
087     * name, without path information. However, some clients, such as the Opera browser, do include path information.
088     *
089     * @return The original file name in the client's file system.
090     * @throws InvalidPathException The file name contains a NUL character, which might be an indicator of a security attack. If you intend to use the file name
091     *                              anyways, catch the exception and use InvalidFileNameException#getName().
092     */
093    String getName();
094
095    /**
096     * Gets an {@link java.io.OutputStream OutputStream} that can be used for storing the contents of the file.
097     *
098     * @return An {@link java.io.OutputStream OutputStream} that can be used for storing the contents of the file.
099     * @throws IOException if an error occurs.
100     */
101    OutputStream getOutputStream() throws IOException;
102
103    /**
104     * Gets the size of the file item.
105     *
106     * @return The size of the file item, in bytes.
107     */
108    long getSize();
109
110    /**
111     * Gets the contents of the file item as a String, using the default character encoding. This method uses {@link #get()} to retrieve the contents of the
112     * item.
113     *
114     * @return The contents of the item, as a string.
115     *
116     * @throws IOException if an I/O error occurs
117     */
118    String getString() throws IOException;
119
120    /**
121     * Gets the contents of the file item as a String, using the specified encoding. This method uses {@link #get()} to retrieve the contents of the item.
122     *
123     * @param toCharset The character encoding to use.
124     * @return The contents of the item, as a string.
125     * @throws IOException if an I/O error occurs
126     */
127    String getString(Charset toCharset) throws IOException;
128
129    /**
130     * Tests whether or not a {@code FileItem} instance represents a simple form field.
131     *
132     * @return {@code true} if the instance represents a simple form field; {@code false} if it represents an uploaded file.
133     */
134    boolean isFormField();
135
136    /**
137     * Tests a hint as to whether or not the file contents will be read from memory.
138     *
139     * @return {@code true} if the file contents will be read from memory; {@code false} otherwise.
140     */
141    boolean isInMemory();
142
143    /**
144     * Sets the field name used to reference this file item.
145     *
146     * @param name The name of the form field.
147     * @return {@code this} instance.
148     */
149    F setFieldName(String name);
150
151    /**
152     * Sets whether or not a {@code FileItem} instance represents a simple form field.
153     *
154     * @param state {@code true} if the instance represents a simple form field; {@code false} if it represents an uploaded file.
155     * @return {@code this} instance.
156     */
157    F setFormField(boolean state);
158
159    /**
160     * Writes an uploaded item to disk.
161     * <p>
162     * The client code is not concerned with whether or not the item is stored in memory, or on disk in a temporary location. They just want to write the
163     * uploaded item to a file.
164     * </p>
165     * <p>
166     * This method is not guaranteed to succeed if called more than once for the same item. This allows a particular implementation to use, for example, file
167     * renaming, where possible, rather than copying all of the underlying data, thus gaining a significant performance benefit.
168     * </p>
169     *
170     * @param file The {@code File} into which the uploaded item should be stored.
171     * @throws IOException if an error occurs.
172     * @return {@code this} instance.
173     */
174    F write(Path file) throws IOException;
175
176}