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.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;

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

import org.directwebremoting.Container;
import org.directwebremoting.ConversionException;
import org.directwebremoting.WebContextFactory;
import org.directwebremoting.extend.AbstractConverter;
import org.directwebremoting.extend.ContainerUtil;
import org.directwebremoting.extend.DataUrlDownloadManager;
import org.directwebremoting.extend.DownloadManager;
import org.directwebremoting.extend.FormField;
import org.directwebremoting.extend.InboundVariable;
import org.directwebremoting.extend.NonNestedOutboundVariable;
import org.directwebremoting.extend.OutboundContext;
import org.directwebremoting.extend.OutboundVariable;
import org.directwebremoting.io.FileTransfer;
import org.directwebremoting.io.InputStreamFactory;
import org.directwebremoting.util.BrowserDetect;
import org.directwebremoting.util.CopyUtils;
import org.directwebremoting.util.UserAgent;

/**
 * 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]
 * @author Joe Walker [joe at getahead dot org]
 * @author Niklas Johansson [niklas dot json at gmail dot com]
 */
public class FileConverter extends AbstractConverter
{
    /* (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) throws ConversionException
    {
        if (data.isNull())
        {
            return null;
        }

        try
        {
            final FormField formField = data.getFormField();
            if (paramType == FileTransfer.class)
            {
                InputStreamFactory inFactory = new InputStreamFactory()
                {
                    public InputStream getInputStream() throws IOException
                    {
                        return formField.getInputStream();
                    }

                    public void close() throws IOException
                    {
                        formField.getInputStream().close();
                    }
                };
                return new FileTransfer(formField.getName(), formField.getMimeType(), formField.getFileSize(), inFactory);
            }
            else if (paramType == InputStream.class)
            {
                return formField.getInputStream();
            }
            else if (paramType == BufferedImage.class)
            {
                return ImageIO.read(formField.getInputStream());
            }
            else if (paramType.isArray() && paramType.getComponentType() == Byte.TYPE)
            {
                InputStream in = formField.getInputStream();
                ByteArrayOutputStream out = new ByteArrayOutputStream();
                CopyUtils.copy(in, out);
                return out.toByteArray();
            }
        }
        catch (IOException ex)
        {
            throw new ConversionException(paramType, ex);
        }

        throw new ConversionException(paramType, "File conversion is not possible for a " + paramType);
    }

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

        try
        {
            FileTransfer transfer;

            if (object instanceof BufferedImage)
            {
                transfer = new FileTransfer((BufferedImage) object, "png");
            }
            else if (object instanceof InputStream)
            {
                final InputStream in = (InputStream) object;
                transfer = new FileTransfer("download.dat", "binary/octet-stream", -1, new InputStreamFactory()
                {
                    public InputStream getInputStream() throws IOException
                    {
                        return in;
                    }

                    public void close() throws IOException
                    {
                        in.close();
                    }
                });
            }
            else if (object instanceof FileTransfer)
            {
                transfer = (FileTransfer) object;
            }
            else if (object.getClass().isArray() && object.getClass().getComponentType() == Byte.TYPE)
            {
                transfer = new FileTransfer("download.dat", "binary/octet-stream", (byte[]) object);
            }
            else
            {
                throw new ConversionException(object.getClass());
            }

            Container container = WebContextFactory.get().getContainer();
            boolean preferDataUrlSchema = ContainerUtil.getBooleanSetting(container, "preferDataUrlSchema", false);

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

            String url = downloadManager.addFileTransfer(transfer);
            return new NonNestedOutboundVariable(url);
        }
        catch (IOException ex)
        {
            throw new ConversionException(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 BrowserDetect.atLeast(request, UserAgent.IE, 8) ||
               BrowserDetect.atLeast(request, UserAgent.Gecko, 20041107) ||
               BrowserDetect.atLeast(request, UserAgent.AppleWebKit, 2) ||
               BrowserDetect.atLeast(request, UserAgent.Opera, 8);
    }
}