downloadUrlToStorageInBackground in ImageList model for imageViewer downloads & overrides the image every time - codenameone

Question

class ImageList implements ListModel<Image> {
private int selection;
private Image[] images;
private EventDispatcher listeners = new EventDispatcher();
public ImageList() {
this.images = new EncodedImage[imageURLs.length];
}
public Image getItemAt(final int index) {
if (images[index] == null) {
images[index] = placeholderForTable;
Util.downloadUrlToStorageInBackground(imageURLs[index], "list" + index, (e) -> {
try {
images[index] = EncodedImage.create(Storage.getInstance().createInputStream("list" + index));
listeners.fireDataChangeEvent(index, DataChangedListener.CHANGED);
} catch (IOException err) {
err.printStackTrace();
}
});
}
return images[index];
}
public int getSize() {
return imageURLs.length;
}
public int getSelectedIndex() {
return selection;
}
public void setSelectedIndex(int index) {
selection = index;
}
public void addDataChangedListener(DataChangedListener l) {
listeners.addListener(l);
}
public void removeDataChangedListener(DataChangedListener l) {
listeners.removeListener(l);
}
public void addSelectionListener(SelectionListener l) {
}
public void removeSelectionListener(SelectionListener l) {
}
public void addItem(Image item) {
}
public void removeItem(int index) {
}
}
protected void postMenuForm(Form f) {
BusinessForumImagesConnection bfic = new BusinessForumImagesConnection();
bfic.businessForumImagesConnectionMethod(new ActionListener() {
#Override
public void actionPerformed(ActionEvent evt) {
if (bfic.response != null) {
for (int i = 0; i < imgLoop; i++) {
HashMap hm = (HashMap) bfic.response.get(i);
String imgUrl = (String) hm.get("imgUrl");
imageURLs[i] = imgUrl;
}
}
}
});
if (imageURLs != null) {
ImageList imodel = new ImageList();
ImageViewer iv = new ImageViewer(imodel.getItemAt(0));
iv.setImageList(imodel);
Container adsContainer = BoxLayout.encloseY(adsLabel, iv);
slideIndex = 0;
Runnable r = new Runnable() {
public void run() {
if (slideIndex < imodel.getSize()) {
nextImage = (Image) imodel.getItemAt(slideIndex);
if (nextImage != null) {
iv.setImage(nextImage);
}
slideIndex++;
} else {
slideIndex = 0;
}
}
};
if (uITimer == null) {
uITimer = new UITimer(r);
}
if (uITimer != null) {
uITimer.schedule(5000, true, f); //5 seconds
}
f.add(BorderLayout.SOUTH, adsContainer);
adsContainer.setLeadComponent(adsLabel);
adsLabel.addActionListener((e) -> {
showForm("BusinessForum", null);
});
}
}
I had used URLImage.createToStorage before but imageViewer didnt work properly so I have used ImageList model. But everytime the form is opened, it jst redownloads the imgs and overrides them in storage, that makes the app slower. How can I make sure if the image is already downloaded, it doesnt download it again and jst shows them in imgViewer? thankyou

Answer 1

The download method will always download regardless...
You need to check if the Storage file exists and if so load that.
See the WebServices/Dogs demo in the new kitchen sink: http://www.codenameone.com/blog/kitchensink-ii.html