MemoryFileItemFactory.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package es.alvsanand.webpage.web.fileupload.common;

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileItemFactory;
import org.apache.commons.io.FileCleaningTracker;


/**
 * <p>The default {@link org.apache.commons.fileupload.FileItemFactory}
 * implementation. This implementation creates
 * {@link org.apache.commons.fileupload.FileItem} instances which keep their
 * content either in memory, for smaller items, or in a temporary file on disk,
 * for larger items. The size threshold, above which content will be stored on
 * disk, is configurable, as is the directory in which temporary files will be
 * created.</p>
 *
 * <p>If not otherwise configured, the default configuration values are as
 * follows:
 * <ul>
 *   <li>Size threshold is 10KB.</li>
 *   <li>Repository is the system default temp directory, as returned by
 *       <code>System.getProperty("java.io.tmpdir")</code>.</li>
 * </ul>
 * </p>
 *
 * <p>Temporary files, which are created for file items, should be
 * deleted later on. The best way to do this is using a
 * {@link FileCleaningTracker}, which you can set on the
 * {@link MemoryFileItemFactory}. However, if you do use such a tracker,
 * then you must consider the following: Temporary files are automatically
 * deleted as soon as they are no longer needed. (More precisely, when the
 * corresponding instance of {@link java.io.File} is garbage collected.)
 * This is done by the so-called reaper thread, which is started
 * automatically when the class {@link org.apache.commons.io.FileCleaner}
 * is loaded.
 * It might make sense to terminate that thread, for example, if
 * your web application ends. See the section on "Resource cleanup"
 * in the users guide of commons-fileupload.</p>
 *
 * @author <a href="mailto:martinc@apache.org">Martin Cooper</a>
 *
 * @since FileUpload 1.1
 *
 * @version $Id: DiskFileItemFactory.java 735374 2009-01-18 02:18:45Z jochen $
 */
public class MemoryFileItemFactory implements FileItemFactory {

    // ----------------------------------------------------- Manifest constants


    /**
     * The default threshold above which uploads will be stored on disk.
     */
    public static final int DEFAULT_SIZE_THRESHOLD = 10240;


    // ----------------------------------------------------- Instance Variables


    /**
     * The threshold above which uploads will be stored on disk.
     */
    private int sizeThreshold = DEFAULT_SIZE_THRESHOLD;

    // ----------------------------------------------------------- Constructors


    /**
     * Constructs an unconfigured instance of this class. The resulting factory
     * may be configured by calling the appropriate setter methods.
     */
    public MemoryFileItemFactory() {
        this(DEFAULT_SIZE_THRESHOLD);
    }


    /**
     * Constructs a preconfigured instance of this class.
     *
     * @param sizeThreshold The threshold, in bytes, below which items will be
     *                      retained in memory and above which they will be
     *                      stored as a file.
     * @param repository    The data repository, which is the directory in
     *                      which files will be created, should the item size
     *                      exceed the threshold.
     */
    public MemoryFileItemFactory(int sizeThreshold) {
        this.sizeThreshold = sizeThreshold;
    }

    // ------------------------------------------------------------- Properties


    /**
     * Returns the size threshold beyond which files are written directly to
     * disk. The default value is 10240 bytes.
     *
     * @return The size threshold, in bytes.
     *
     * @see #setSizeThreshold(int)
     */
    public int getSizeThreshold() {
        return sizeThreshold;
    }


    /**
     * Sets the size threshold beyond which files are written directly to disk.
     *
     * @param sizeThreshold The size threshold, in bytes.
     *
     * @see #getSizeThreshold()
     *
     */
    public void setSizeThreshold(int sizeThreshold) {
        this.sizeThreshold = sizeThreshold;
    }


    // --------------------------------------------------------- Public Methods

    /**
     * Create a new {@link es.alvsanand.webpage.web.fileupload.common.MemoryFileItem}
     * instance from the supplied parameters and the local factory
     * configuration.
     *
     * @param fieldName   The name of the form field.
     * @param contentType The content type of the form field.
     * @param isFormField <code>true</code> if this is a plain form field;
     *                    <code>false</code> otherwise.
     * @param fileName    The name of the uploaded file, if any, as supplied
     *                    by the browser or other client.
     *
     * @return The newly created file item.
     */
    public FileItem createItem(String fieldName, String contentType,
            boolean isFormField, String fileName) {
        MemoryFileItem result = new MemoryFileItem(fieldName, contentType,
                isFormField, fileName, sizeThreshold);
        return result;
    }
}