org.directwebremoting.convert.FileConverter Maven / Gradle / Ivy

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DWR is easy Ajax for Java. It makes it simple to call Java code directly from Javascript. It gets rid of almost all the boiler plate code between the web browser and your Java code.
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/*
 * Copyright 2005 Joe Walker
 *
 * 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.directwebremoting.convert;

import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.InputStream;

import javax.imageio.ImageIO;
import javax.servlet.http.HttpServletRequest;

import org.directwebremoting.WebContextFactory;
import org.directwebremoting.extend.Converter;
import org.directwebremoting.extend.DownloadManager;
import org.directwebremoting.extend.FileGenerator;
import org.directwebremoting.extend.FormField;
import org.directwebremoting.extend.InboundContext;
import org.directwebremoting.extend.InboundVariable;
import org.directwebremoting.extend.MarshallException;
import org.directwebremoting.extend.NonNestedOutboundVariable;
import org.directwebremoting.extend.OutboundContext;
import org.directwebremoting.extend.OutboundVariable;
import org.directwebremoting.impl.DataUrlDownloadManager;
import org.directwebremoting.impl.FileTransferFileGenerator;
import org.directwebremoting.impl.ImageIOFileGenerator;
import org.directwebremoting.impl.InputStreamFileGenerator;
import org.directwebremoting.io.FileTransfer;
import org.directwebremoting.util.Messages;

/**
 * The FileConverter can only convert inbound files, convertOutbound is not
 * supported. 
 * Files come from an <input type="file"/> on the client.
 * @author Lance Semmens [uklance at gmail dot com]
 */
public class FileConverter extends BaseV20Converter implements Converter
{
    /* (non-Javadoc)
     * @see org.directwebremoting.extend.Converter#convertInbound(java.lang.Class, org.directwebremoting.extend.InboundVariable, org.directwebremoting.extend.InboundContext)
     */
    public Object convertInbound(Class paramType, InboundVariable data, InboundContext inctx) throws MarshallException
    {
        FormField formField = data.getFormField();
        if (paramType == FileTransfer.class)
        {
            return new FileTransfer(formField.getName(), formField.getMimeType(), formField.getInputStream());
        }
        else if (paramType == InputStream.class)
        {
            return formField.getInputStream();
        }
        else if (paramType == BufferedImage.class)
        {
            try
            {
                return ImageIO.read(formField.getInputStream());
            }
            catch (IOException ex)
            {
                throw new MarshallException(paramType, ex);
            }
        }

        throw new MarshallException(paramType, Messages.getString("MarshallException.FileFailure", paramType));
    }

    /* (non-Javadoc)
     * @see org.directwebremoting.extend.Converter#convertOutbound(java.lang.Object, org.directwebremoting.extend.OutboundContext)
     */
    public OutboundVariable convertOutbound(Object object, OutboundContext outboundContext) throws MarshallException
    {
        if (object == null)
        {
            return new NonNestedOutboundVariable("null");
        }

        try
        {
            FileGenerator generator;

            if (object instanceof BufferedImage)
            {
                BufferedImage image = (BufferedImage) object;
                generator = new ImageIOFileGenerator(image, "image/png", "image", "png");
            }
            else if (object instanceof InputStream)
            {
                InputStream in = (InputStream) object;
                generator = new InputStreamFileGenerator(in, "download.dat", "binary/octet-stream");
            }
            else if (object instanceof FileTransfer)
            {
                FileTransfer in = (FileTransfer) object;
                generator = new FileTransferFileGenerator(in);
            }
            else
            {
                throw new MarshallException(object.getClass());
            }

            DownloadManager downloadManager;
            if (preferDataUrlSchema && isDataUrlAvailable())
            {
                downloadManager = new DataUrlDownloadManager();
            }
            else
            {
                downloadManager = WebContextFactory.get().getContainer().getBean(DownloadManager.class);
            }

            String url = downloadManager.addFile(generator);
            return new NonNestedOutboundVariable(url);
        }
        catch (IOException ex)
        {
            throw new MarshallException(getClass(), ex);
        }
    }

    /**
     * Is the data: URL allowed by the current browser.
     * @return true if data: is allowed
     */
    protected boolean isDataUrlAvailable()
    {
        HttpServletRequest request = WebContextFactory.get().getHttpServletRequest();
        return request.getHeader("user-agent").indexOf("MSIE") == -1;
    }

    /**
     * Do we use a data: URL when we know it will work
     * @param preferDataUrlSchema
     */
    public void setPreferDataUrlSchema(boolean preferDataUrlSchema)
    {
        this.preferDataUrlSchema = preferDataUrlSchema;
    }

    /**
     * Do we use data: URLs when we can?
     */
    private boolean preferDataUrlSchema = false;
}