Wednesday, 2 April 2014

How to a file download without download button/link etc.. in Vaadin 7


Request us for the complete code. If number of request reached 15, then the complete source code with demo will be published here.

For now, http://vaadintutorial.blogspot.in/2014/03/how-to-download-file-from-server-in.html

Saturday, 29 March 2014

Friday, 14 March 2014

How to download a file from the server in Vaadin 7 on demand / late binding of file / dynamically

Here is an advanced file downloader class which can set/change a file on each click of its download.
For instance, consider we have a download button/link and we want to change the file on the click of the button. This can be achieved by this component. This component has a common listener called AdvancedDownloaderListener.beforeDownload which will invoke when we click the button/link etc.. just before the download starts, so that we can change the file path. And, the changed file can be downloaded. 

The complete code with sample code is given below


The vaadin framework is build up on GWT libraries..

But my favourate framework is wffweb.


package com.example.samplevaadin.ui.componet.custom;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.util.logging.Logger;

import com.vaadin.server.ConnectorResource;
import com.vaadin.server.DownloadStream;
import com.vaadin.server.FileDownloader;
import com.vaadin.server.Resource;
import com.vaadin.server.StreamResource;
import com.vaadin.server.VaadinService;
import com.vaadin.server.VaadinSession;
import com.vaadin.server.StreamResource.StreamSource;
import com.vaadin.server.VaadinRequest;
import com.vaadin.server.VaadinResponse;
import com.vaadin.ui.AbstractComponent;

/**
 * an advanced file downloader
 *
 * @author visruth
 *
 */
public class AdvancedFileDownloader extends FileDownloader {

    /**
     *
     */
    private static final long serialVersionUID = 7914516170514586601L;
    private static final boolean DEBUG_MODE = true;

    private static final Logger logger = java.util.logging.Logger
            .getLogger(AdvancedFileDownloader.class.getName());

    private AbstractComponent extendedComponet;

    private AdvancedDownloaderListener dynamicDownloaderListener;
    private DownloaderEvent downloadEvent;

    public abstract class DownloaderEvent {

        /**
         *
         * @return
         */
        public abstract AbstractComponent getExtendedComponet();

        public abstract void setExtendedComponet(
                AbstractComponent extendedComponet);

    }

    public interface AdvancedDownloaderListener {
        /**
         * This method will be invoked just before the download starts. Thus, a
         * new file path can be set.
         *
         * @param downloadEvent
         */
        public void beforeDownload(DownloaderEvent downloadEvent);
    }

    public void fireEvent() {
        if (DEBUG_MODE) {
            logger.info("inside fireEvent");
        }
        if (this.dynamicDownloaderListener != null
                && this.downloadEvent != null) {
            if (DEBUG_MODE) {
                logger.info("beforeDownload is going to be invoked");
            }
            this.dynamicDownloaderListener.beforeDownload(this.downloadEvent);
        }
    }

    public void addAdvancedDownloaderListener(
            AdvancedDownloaderListener listener) {
        if (listener != null) {
            DownloaderEvent downloadEvent = new DownloaderEvent() {

                private AbstractComponent extendedComponet;

                @Override
                public void setExtendedComponet(
                        AbstractComponent extendedComponet) {
                    this.extendedComponet = extendedComponet;
                }

                @Override
                public AbstractComponent getExtendedComponet() {
                    // TODO Auto-generated method stub
                    return this.extendedComponet;
                }
            };
            downloadEvent
                    .setExtendedComponet(AdvancedFileDownloader.this.extendedComponet);
            this.dynamicDownloaderListener = listener;
            this.downloadEvent = downloadEvent;

        }
    }

    private static class FileResourceUtil {

        private String filePath;

        private String fileName = "";

        private File file;

        public String getFilePath() {
            return filePath;
        }

        public void setFilePath(String filePath) {
            this.filePath = filePath;
            file = new File(filePath);

            if (file.exists() && !file.isDirectory()) {
                fileName = file.getName();
            }
        }

        /**
         * makes a stream resource
         *
         * @return {@code StreamResource}
         */
        @SuppressWarnings("serial")
        public StreamResource getResource() {
            return new StreamResource(new StreamSource() {

                @Override
                public InputStream getStream() {

                    if (filePath != null && file != null) {

                        if (file.exists() && !file.isDirectory()) {
                            try {
                                return new FileInputStream(file);
                            } catch (FileNotFoundException e) {
                                e.printStackTrace();
                                return null;
                            }
                        } else {
                            return null;
                        }

                    }
                    return null;
                }

            }, FileResourceUtil.this.fileName) {
                @Override
                public String getFilename() {
                    return FileResourceUtil.this.fileName;
                }

            };
        }

    }

    private FileResourceUtil resource;

    private AdvancedFileDownloader(FileResourceUtil resource) {

        super(resource == null ? (resource = new FileResourceUtil())
                .getResource() : resource.getResource());

        AdvancedFileDownloader.this.resource = resource;
        System.out.println("created a new instance of resource : " + resource);
    }

    public AdvancedFileDownloader() {
        this(null);
    }

    /**
     * @return the current file path
     */
    public String getFilePath() {
        return resource.getFilePath();
    }

    /**
     * sets the path for the file for downloading
     *
     * @param filePath
     *            path of the file, i.e. path + file name with extension
     */
    public void setFilePath(String filePath) {

        if (resource != null && filePath != null) {
            this.resource.setFilePath(filePath);
            ;
        }
    }

    @Override
    public boolean handleConnectorRequest(VaadinRequest request,
            VaadinResponse response, String path) throws IOException {

      
        if (!path.matches("dl(/.*)?")) {
            // Ignore if it isn't for us
            return false;
        }
        VaadinSession session = getSession();

        session.lock();
        AdvancedFileDownloader.this.fireEvent();

        DownloadStream stream;

        try {
            Resource resource = getFileDownloadResource();
            if (!(resource instanceof ConnectorResource)) {
                return false;
            }
            stream = ((ConnectorResource) resource).getStream();

            if (stream.getParameter("Content-Disposition") == null) {
                // Content-Disposition: attachment generally forces download
                stream.setParameter("Content-Disposition",
                        "attachment; filename=\"" + stream.getFileName() + "\"");
            }

            // Content-Type to block eager browser plug-ins from hijacking
            // the file
            if (isOverrideContentType()) {
                stream.setContentType("application/octet-stream;charset=UTF-8");
            }
          
        } finally {
            session.unlock();
        }
        stream.writeResponse(request, response);
        return true;
    }
}


Sample code to run :



package com.example.samplevaadin;

import javax.servlet.annotation.WebServlet;

import com.example.samplevaadin.ui.componet.custom.AdvancedFileDownloader;
import com.example.samplevaadin.ui.componet.custom.AdvancedFileDownloader.AdvancedDownloaderListener;
import com.example.samplevaadin.ui.componet.custom.AdvancedFileDownloader.DownloaderEvent;
import com.vaadin.annotations.Theme;
import com.vaadin.annotations.VaadinServletConfiguration;
import com.vaadin.server.VaadinRequest;
import com.vaadin.server.VaadinServlet;
import com.vaadin.ui.Button;
import com.vaadin.ui.Link;
import com.vaadin.ui.TextField;
import com.vaadin.ui.UI;
import com.vaadin.ui.VerticalLayout;

@SuppressWarnings("serial")
@Theme("samplevaadin")
public class DemoUI extends UI {

    @WebServlet(value = "/*", asyncSupported = true)
    @VaadinServletConfiguration(productionMode = false, ui = DemoUI.class)
    public static class Servlet extends VaadinServlet {
    }

    @Override
    protected void init(VaadinRequest request) {

        final VerticalLayout layout = new VerticalLayout();
        layout.setMargin(true);

       
        final TextField inputFilepathField = new TextField();
        inputFilepathField.setValue("/home/visruthcv/README.txt");
        inputFilepathField.setImmediate(true);
        layout.addComponent(inputFilepathField);

        Button downloadButton = new Button("Download Button");
        // or
        Link downloadLink = new Link();
        downloadLink.setCaption("Download link");

        final AdvancedFileDownloader downloader = new AdvancedFileDownloader();
        downloader
                .addAdvancedDownloaderListener(new AdvancedDownloaderListener() {

                    /**
                     * This method will be invoked just before the download
                     * starts. Thus, a new file path can be set.
                     *
                     * @param downloadEvent
                     */
                    @Override
                    public void beforeDownload(DownloaderEvent downloadEvent) {

                        String filePath = inputFilepathField.getValue();

                        downloader.setFilePath(filePath);
                       
                        System.out.println("Starting downlad by button "
                                + filePath.substring(filePath.lastIndexOf("/")));
                    }

                });

        downloader.extend(downloadButton);
        layout.addComponent(downloadButton);

        final AdvancedFileDownloader downloaderForLink = new AdvancedFileDownloader();
        downloaderForLink
                .addAdvancedDownloaderListener(new AdvancedDownloaderListener() {

                    /**
                     * This method will be invoked just before the download
                     * starts. Thus, a new file path can be set.
                     *
                     * @param downloadEvent
                     */
                    @Override
                    public void beforeDownload(DownloaderEvent downloadEvent) {

                        String filePath = inputFilepathField.getValue();

                        downloaderForLink.setFilePath(filePath);
                        System.out.println("Starting download by link "
                                + filePath.substring(filePath.lastIndexOf("/")));
                       
                    }

                });

        downloaderForLink.extend(downloadLink);
        layout.addComponent(downloadLink);

        setContent(layout);
    }

}



Please request us if you want to add any other functionality in AdvancedFileDownloader class. You can also request us for any special case requirement for which you didn't find any solution anywhere.

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Tuesday, 4 March 2014

Request us for a tutorial fo Vaadin

Request us for a tutorial (any of Vaadin functionality) which you don't find anywhere online, we will post it.