de.tudarmstadt.ukp.csniper.webapp.support.wicket.AjaxFileDownload.java Source code

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/*******************************************************************************
 * Copyright 2013
 * Ubiquitous Knowledge Processing (UKP) Lab
 * Technische Universitt Darmstadt
 * 
 * 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 de.tudarmstadt.ukp.csniper.webapp.support.wicket;

import java.io.File;

import org.apache.wicket.ajax.AjaxRequestTarget;
import org.apache.wicket.behavior.AbstractAjaxBehavior;
import org.apache.wicket.request.IRequestCycle;
import org.apache.wicket.request.handler.resource.ResourceStreamRequestHandler;
import org.apache.wicket.request.http.WebResponse;
import org.apache.wicket.request.resource.ContentDisposition;
import org.apache.wicket.util.file.Files;
import org.apache.wicket.util.resource.FileResourceStream;
import org.apache.wicket.util.resource.IResourceStream;

public class AjaxFileDownload extends AbstractAjaxBehavior {
    private static final long serialVersionUID = -2488536366826706596L;

    private File file;
    private String filename;
    private String contentType;

    /**
     * Call this method to initiate the download.
     */
    public void initiate(AjaxRequestTarget target, File aFile, String aFilename, String aContentType) {
        file = aFile;
        filename = aFilename;
        contentType = aContentType;

        String url = getCallbackUrl().toString();
        url = url + (url.contains("?") ? "&" : "?");
        url = url + "antiCache=" + System.currentTimeMillis();

        // the timeout is needed to let Wicket release the channel
        target.appendJavaScript("setTimeout(\"window.location.href='" + url + "'\", 100);");
    }

    @Override
    public void onRequest() {
        IResourceStream resourceStream = new FileResourceStream(file);
        getComponent().getRequestCycle()
                .scheduleRequestHandlerAfterCurrent(new ResourceStreamRequestHandler(resourceStream) {
                    @Override
                    public void respond(IRequestCycle requestCycle) {
                        ((WebResponse) requestCycle.getResponse()).setContentType(contentType);
                        super.respond(requestCycle);
                        Files.remove(file);
                    }
                }.setFileName(filename).setContentDisposition(ContentDisposition.ATTACHMENT));
    }
}