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jsfjsf-2primefaces
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Reputation: 18712

Why does an image in graphicImage not load fully (PrimeFaces mobile)?

I have an application, which uses PrimeFaces Mobile to display images.

Sometimes, but not always, the image is not displayed fully - only the top part.

Screenshot

The XHTML code of the page with that image looks like this:

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml"
      xmlns:h="http://java.sun.com/jsf/html"
      xmlns:f="http://java.sun.com/jsf/core"
      xmlns:p="http://primefaces.org/ui"
      xmlns:pm="http://primefaces.org/mobile">

<f:view renderKitId="PRIMEFACES_MOBILE"/>

<h:head>

</h:head>

<f:event listener="#{main.loadFirstImage}" type="preRenderView" />

<h:body id="body">

    <pm:page id="page">
        <pm:header title="myapp">
        </pm:header>

        <pm:content id="content">
            <h:form>
                <p:graphicImage id="image" rendered="false" value="#{main.currentImage()}"
                                cache="false">
                </p:graphicImage>

                [...]

            </h:form>
        </pm:content>

        <pm:footer title="m.myapp.com"></pm:footer>
    </pm:page>
</h:body>

</html>

And the main bean has following code:

@ManagedBean(name = "main")
@SessionScoped
public class MainView {

    private byte[] currentImageData;
    private byte[] productId;
    private byte[] imageId;

    public void loadFirstImage()
    {
        // This method initializes currentImageData
        fetchNextImage();
    }

    [...]

    public StreamedContent currentImage()
    {
        FacesContext context = FacesContext.getCurrentInstance();

        if (context.getCurrentPhaseId() == PhaseId.RENDER_RESPONSE) {
            return new DefaultStreamedContent();
        }
        else {
            return new DefaultStreamedContent(new ByteArrayInputStream(currentImageData));
        }
    }

    [...]
}

How can I fix this error?

Update 1 (03.11.2014 23:21 MSK):

I've tried following to fix the error:

1) Disabling cache for all elements of that Primefaces page.

2) Disabling response chunking by setting maxExtensionSize and maxTrailerSize (server.xml) to -1.

Response chunking settings

3) Adding a filter with following doFilter:

@Override
public void doFilter(final ServletRequest aServletRequest,
                     final ServletResponse aServletResponse,
                     final FilterChain aFilterChain) throws IOException, ServletException {
    System.out.println("aServletRequest instanceof HttpServletRequest: " +
            (aServletRequest instanceof HttpServletRequest));

    if (aServletRequest instanceof HttpServletRequest)
    {
        final HttpServletRequest request = (HttpServletRequest) aServletRequest;

        final String requestURI = request.getRequestURI().toLowerCase();

        if (!requestURI.endsWith("/javax.faces.resource/dynamiccontent.properties"))
        {
            aFilterChain.doFilter(aServletRequest, aServletResponse);
        }
    }
}

4) Changing the currentImage method to 

public StreamedContent currentImage()
{
    FacesContext context = FacesContext.getCurrentInstance();

    if (context.getCurrentPhaseId() == PhaseId.RENDER_RESPONSE) {
        // So, we're rendering the view. Return a stub StreamedContent so that it will generate right URL.
        return new DefaultStreamedContent();
    }
    else {
        String mimeType = null;

        if (imageFileName.toLowerCase().endsWith(".png"))
        {
            mimeType = "image/png";
        }
        else if (imageFileName.toLowerCase().endsWith(".jpeg") || imageFileName.toLowerCase().endsWith(".jpg"))
        {
            mimeType = "image/jpeg";
        }

        // So, browser is requesting the image. Return a real StreamedContent with the image bytes.
        return new DefaultStreamedContent(new ByteArrayInputStream(currentImageData), mimeType);
    }
}

But it still doesn't work. I wrote a piece of code in another web application and using different framework (Vaadin), which displays images from the same source.

I get the same error (images are displayed only partially).

From this I conclude that the error must occur

  1. when images are retrieved from a particular and/or
  2. when images are saved in MongoDB.

Code for retrieving images from URL

If the error occurs during reading the image, it occurs in the following method:

protected Binary readImage(final String viewItemURL) {
    InputStream inputStream = null;
    Binary image = null;
    try
    {
        inputStream = new URL(viewItemURL).openStream();;
        byte bytes[] = new byte[inputStream.available()];
        inputStream.read(bytes);

        image = new Binary(bytes);
    }
    catch (final IOException exception)
    {
        LOGGER.error("", exception);
    }
    finally
    {
        IOUtils.closeQuietly(inputStream);
    }
    return image;
}

viewItemURL is the URL of the image.

Code for saving image in MongoDB

If the problem is with saving images in the database, it occurs in the following method:

protected void saveProductImages(final byte[] aNewProductId, final List<String> aPictureUrls,
                               final IMongoPersistenceState aPersistenceState) {
    final DB db = aPersistenceState.getDb();
    final DBCollection productImagesColl = db.getCollection(
            MyAppPersistenceAction.COLLECTION_USER_PRODUCT_IMAGES);

    for (final String curPictureUrl : aPictureUrls)
    {
        final Binary imageData = readImage(curPictureUrl);

        final Map<String,Object> map = new HashMap<String, Object>();

        map.put(FIELD_COLLECTION_USER_PRODUCT_IMAGES_CREATOR_EMAIL, CREATOR_EMAIL);
        map.put(FIELD_COLLECTION_USER_PRODUCT_IMAGES_PRODUCT_ID, aNewProductId);
        map.put(FIELD_COLLECTION_USER_PRODUCT_IMAGES_DATA, imageData);
        final String fileName = extractFileName(curPictureUrl);
        map.put(FIELD_COLLECTION_USER_PRODUCT_IMAGES_FILE_NAME, fileName);
        map.put(FIELD_COLLECTION_USER_PRODUCT_IMAGES_MIME_TYPE, getMimeType(fileName));
        map.put(FIELD_COLLECTION_USER_PRODUCT_IMAGES_IS_DELETED, Boolean.FALSE);

        productImagesColl.insert(WriteConcern.SAFE, createRecordObject(map));
    }
}

Upvotes: 1

Views: 1836

Answers (1)

BalusC
BalusC

Reputation: 1108632

Your readImage() method has a major bug:

byte bytes[] = new byte[inputStream.available()];

The InputStream#available() doesn't do what you think it does. It doesn't return the total content length which is what the remainder of the code is expecting. It returns the amount of bytes available for reading without blocking all other threads (i.e. bytes which are currently already put in hardware buffer). This totally explains why you get only that part of the image to display.

No need to be ashamed. Practically all Java starters make the same mistake. The right way to read an InputStream fully is to invoke any read() method on it as long as until it returns -1 indicating EOF (end of file). You can find a bunch of examples and utility library shortcuts in this related question: Convert InputStream to byte array in Java.

Here's a full rewrite of readImage() method doing the right thing, making use of IOUtils which you appear to already have at your hands (and Java 7's try-with-resources with AutoCloseable):

protected Binary readImage(final String viewItemURL) {
    try (InputStream inputStream = new URL(viewItemURL).openStream()) {
        return new Binary(IOUtils.toByteArray(inputStream));
    }
    catch (final IOException exception) {
        LOGGER.error("", exception);
        return null;
    }
}

Upvotes: 4

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