servletfileupload.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.servlet;

import java.util.List;
import javax.servlet.http.HttpServletRequest;
import org.apache.commons.fileupload.FileItemFactory;
import org.apache.commons.fileupload.FileUpload;
import org.apache.commons.fileupload.FileUploadException;

/**
 * <p>High level API for processing file uploads.</p>
 *
 * <p>This class handles multiple files per single HTML widget, sent using
 * <code>multipart/mixed</code> encoding type, as specified by
 * <a href="http://www.ietf.org/rfc/rfc1867.txt">RFC 1867</a>.  Use {@link
 * #parseRequest(HttpServletRequest)} to acquire a list of {@link
 * org.apache.commons.fileupload.FileItem}s associated with a given HTML
 * widget.</p>
 *
 * <p>How the data for individual parts is stored is determined by the factory
 * used to create them; a given part may be in memory, on disk, or somewhere
 * else.</p>
 *
 * @author <a href="mailto:[e-mail]">Rafal Krzewski</a>
 * @author <a href="mailto:[e-mail]">Daniel Rall</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
 *
 * @version $Id: ServletFileUpload.java 350090 2005-12-01 00:56:20Z martinc $
 */
public class ServletFileUpload extends FileUpload {

    // ---------------------------------------------------------- Class methods


    /**
     * Utility method that determines whether the request contains multipart
     * content.
     *
     * @param req The servlet request to be evaluated. Must be non-null.
     *
     * @return <code>true</code> if the request is multipart;
     *         <code>false</code> otherwise.
     */
    //NOTE: This method cannot be enabled until the one in FileUploadBase is
    //      removed, since it is not possible to override a static method.
    //public static final boolean isMultipartContent(
    //        HttpServletRequest request) {
    //    if (!"post".equals(request.getMethod().toLowerCase())) {
    //        return false;
    //    }
    //    return FileUploadBase.isMultipartContent(
    //            new ServletRequestContext(request));
    //}


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


    /**
     * Constructs an uninitialised instance of this class. A factory must be
     * configured, using <code>setFileItemFactory()</code>, before attempting
     * to parse requests.
     *
     * @see FileUpload#FileUpload(FileItemFactory)
     */
    public ServletFileUpload() {
        super();
    }


    /**
     * Constructs an instance of this class which uses the supplied factory to
     * create <code>FileItem</code> instances.
     *
     * @see FileUpload#FileUpload()
     */
    public ServletFileUpload(FileItemFactory fileItemFactory) {
        super(fileItemFactory);
    }


    // --------------------------------------------------------- Public methods


    /**
     * Processes an <a href="http://www.ietf.org/rfc/rfc1867.txt">RFC 1867</a>
     * compliant <code>multipart/form-data</code> stream.
     *
     * @param request The servlet request to be parsed.
     *
     * @return A list of <code>FileItem</code> instances parsed from the
     *         request, in the order that they were transmitted.
     *
     * @throws FileUploadException if there are problems reading/parsing
     *                             the request or storing files.
     */
    public List /* FileItem */ parseRequest(HttpServletRequest request)
            throws FileUploadException {
        return parseRequest(new ServletRequestContext(request));
    }
}