diskfileitem.java

java上传文件的一个例子。使用了apache的第三方开源组件。

/*
 * Copyright 2001-2005 The Apache Software Foundation
 *
 * Licensed 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 org.apache.commons.fileupload.disk;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.ObjectOutputStream;
import java.io.ObjectInputStream;
import java.io.UnsupportedEncodingException;
import java.rmi.server.UID;
import java.util.Map;
import org.apache.commons.io.IOUtils;
import org.apache.commons.io.FileCleaner;
import org.apache.commons.io.output.DeferredFileOutputStream;

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.ParameterParser;


/**
 * <p> The default implementation of the
 * {@link org.apache.commons.fileupload.FileItem FileItem} interface.
 *
 * <p> After retrieving an instance of this class from a {@link
 * org.apache.commons.fileupload.DiskFileUpload DiskFileUpload} instance (see
 * {@link org.apache.commons.fileupload.DiskFileUpload
 * #parseRequest(javax.servlet.http.HttpServletRequest)}), you may
 * either request all contents of file at once using {@link #get()} or
 * request an {@link java.io.InputStream InputStream} with
 * {@link #getInputStream()} and process the file without attempting to load
 * it into memory, which may come handy with large files.
 *
 * @author <a href="mailto:[e-mail]">Rafal Krzewski</a>
 * @author <a href="mailto:[e-mail]">Sean Legassick</a>
 * @author <a href="mailto:[e-mail]">Jason van Zyl</a>
 * @author <a href="mailto:[e-mail]">John McNally</a>
 * @author <a href="mailto:[e-mail]">Martin Cooper</a>
 * @author Sean C. Sullivan
 *
 * @since FileUpload 1.1
 *
 * @version $Id: DiskFileItem.java 399546 2006-05-04 04:53:30Z martinc $
 */
public class DiskFileItem
    implements FileItem {

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


    /**
     * Default content charset to be used when no explicit charset
     * parameter is provided by the sender. Media subtypes of the
     * "text" type are defined to have a default charset value of
     * "ISO-8859-1" when received via HTTP.
     */
    public static final String DEFAULT_CHARSET = "ISO-8859-1";


    // ----------------------------------------------------------- Data members


    /**
     * UID used in unique file name generation.
     */
    private static final String UID =
            new UID().toString().replace(':', '_').replace('-', '_');

    /**
     * Counter used in unique identifier generation.
     */
    private static int counter = 0;


    /**
     * The name of the form field as provided by the browser.
     */
    private String fieldName;


    /**
     * The content type passed by the browser, or <code>null</code> if
     * not defined.
     */
    private String contentType;


    /**
     * Whether or not this item is a simple form field.
     */
    private boolean isFormField;


    /**
     * The original filename in the user's filesystem.
     */
    private String fileName;


    /**
     * The size of the item, in bytes. This is used to cache the size when a
     * file item is moved from its original location.
     */
    private long size = -1;


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


    /**
     * The directory in which uploaded files will be stored, if stored on disk.
     */
    private File repository;


    /**
     * Cached contents of the file.
     */
    private byte[] cachedContent;


    /**
     * Output stream for this item.
     */
    private transient DeferredFileOutputStream dfos;

    /**
     * File to allow for serialization of the content of this item.
     */
    private File dfosFile;


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


    /**
     * Constructs a new <code>DiskFileItem</code> instance.
     *
     * @param fieldName     The name of the form field.
     * @param contentType   The content type passed by the browser or
     *                      <code>null</code> if not specified.
     * @param isFormField   Whether or not this item is a plain form field, as
     *                      opposed to a file upload.
     * @param fileName      The original filename in the user's filesystem, or
     *                      <code>null</code> if not specified.
     * @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 DiskFileItem(String fieldName, String contentType,
            boolean isFormField, String fileName, int sizeThreshold,
            File repository) {
        this.fieldName = fieldName;
        this.contentType = contentType;
        this.isFormField = isFormField;
        this.fileName = fileName;
        this.sizeThreshold = sizeThreshold;
        this.repository = repository;
    }


    // ------------------------------- Methods from javax.activation.DataSource


    /**
     * Returns an {@link java.io.InputStream InputStream} that can be
     * used to retrieve the contents of the file.
     *
     * @return An {@link java.io.InputStream InputStream} that can be
     *         used to retrieve the contents of the file.
     *
     * @throws IOException if an error occurs.
     */
    public InputStream getInputStream()
        throws IOException {
        if (!isInMemory()) {
            return new FileInputStream(dfos.getFile());
        }

        if (cachedContent == null) {
            cachedContent = dfos.getData();
        }
        return new ByteArrayInputStream(cachedContent);
    }


    /**
     * Returns the content type passed by the agent or <code>null</code> if
     * not defined.
     *
     * @return The content type passed by the agent or <code>null</code> if
     *         not defined.
     */
    public String getContentType() {
        return contentType;
    }


    /**
     * Returns the content charset passed by the agent or <code>null</code> if
     * not defined.
     *
     * @return The content charset passed by the agent or <code>null</code> if
     *         not defined.
     */
    public String getCharSet() {
        ParameterParser parser = new ParameterParser();
        parser.setLowerCaseNames(true);
        // Parameter parser can handle null input
        Map params = parser.parse(getContentType(), ';');
        return (String) params.get("charset");
    }


    /**
     * Returns the original filename in the client's filesystem.
     *
     * @return The original filename in the client's filesystem.
     */
    public String getName() {
        return fileName;
    }


    // ------------------------------------------------------- FileItem methods


    /**
     * Provides a hint as to whether or not the file contents will be read
     * from memory.
     *
     * @return <code>true</code> if the file contents will be read
     *         from memory; <code>false</code> otherwise.
     */
    public boolean isInMemory() {
        if (cachedContent != null) {
            return true;
        } else {
            return dfos.isInMemory();
        }
    }


    /**
     * Returns the size of the file.
     *
     * @return The size of the file, in bytes.
     */
    public long getSize() {
        if (size >= 0) {
            return size;
        } else if (cachedContent != null) {
            return cachedContent.length;
        } else if (dfos.isInMemory()) {
            return dfos.getData().length;
        } else {
            return dfos.getFile().length();
        }
    }


    /**
     * Returns the contents of the file as an array of bytes.  If the
     * contents of the file were not yet cached in memory, they will be
     * loaded from the disk storage and cached.
     *
     * @return The contents of the file as an array of bytes.
     */
    public byte[] get() {
        if (isInMemory()) {
            if (cachedContent == null) {
                cachedContent = dfos.getData();
            }
            return cachedContent;
        }

        byte[] fileData = new byte[(int) getSize()];
        FileInputStream fis = null;

        try {
            fis = new FileInputStream(dfos.getFile());
            fis.read(fileData);
        } catch (IOException e) {
            fileData = null;
        } finally {
            if (fis != null) {
                try {
                    fis.close();
                } catch (IOException e) {
                    // ignore
                }
            }
        }

        return fileData;
    }


    /**
     * Returns the contents of the file as a String, using the specified
     * encoding.  This method uses {@link #get()} to retrieve the
     * contents of the file.
     *
     * @param charset The charset to use.
     *
     * @return The contents of the file, as a string.
     *
     * @throws UnsupportedEncodingException if the requested character
     *                                      encoding is not available.
     */
    public String getString(final String charset)
        throws UnsupportedEncodingException {
        return new String(get(), charset);
    }


    /**
     * Returns the contents of the file as a String, using the default
     * character encoding.  This method uses {@link #get()} to retrieve the
     * contents of the file.
     *