How to read the data in a Blob in WebView on Android? [duplicate]

Question

I have a server that creates an object blob on the browser and I want to download this within WebView in an Android app. I tried redirecting the request to the browser instance as well as using the download manager to do this, but neither of them seems to work (Even though if I open up the same page in Chrome, the download operation works there).

I tried the following code,it throws error:

Android.content.ActivityNotFoundException: No Activity found to handle Intent { act=android.intent.action.VIEW dat=blob:https%3A//111.111.111.111%3A8080/40b63131-63b1-4fa4-9451-c6297bbd111a"

Edit

Android.content.ActivityNotFoundException: No Activity found to handle Intent { act=android.intent.action.VIEW dat=blob:http://digitalinsensu.com/0f0d6127-a0f1-44c3-af85-72f648258d6d

Code:

mWebView.setDownloadListener(new DownloadListener() {
public void onDownloadStart(String url, String userAgent,String contentDisposition, String mimetype,long contentLength) {
    Intent i = new Intent(Intent.ACTION_VIEW);
    i.setData(Uri.parse(url));
    startActivity(i);
}
});

and this throws java.lang.IllegalArgumentException: Can only download HTTP/HTTPS URIs error:

mWebView.setDownloadListener(new DownloadListener() {
    public void onDownloadStart(String url, String userAgent,String contentDisposition, String mimetype,long contentLength) {
        DownloadManager.Request request = new DownloadManager.Request(Uri.parse(url));
        request.allowScanningByMediaScanner();
        request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
        request.setDestinationInExternalPublicDir(Environment.DIRECTORY_DOWNLOADS, "download");
        DownloadManager dm = (DownloadManager) getSystemService(DOWNLOAD_SERVICE);
        dm.enqueue(request);

    }
});

How should I be downloading the blob? Any help would be appreciated.

Why would you use a webview to download an object? It won't know how to parse anything but a webpage. Use DownloadManager instead. — Gabe Sechan
– Gabe Sechan, Commented Feb 15, 2016 at 2:39
@GabeSechan I load a url in my webview that does a bunch of things and creates a blob, and I want to download that to the device. — Alice Van Der Land
– Alice Van Der Land, Commented Feb 15, 2016 at 2:43
@DougStevenson I understand that the code does not work because it tries to operate on a blob saved on the browser rather than an HTTP address, but I have not been able to find how to download a blob in Android. — Alice Van Der Land
– Alice Van Der Land, Commented Feb 15, 2016 at 2:46
@GulizTuncay If the url string is just "blob:" I don't think there's anything you can do with that to get to the data you want. — Doug Stevenson
– Doug Stevenson, Commented Feb 15, 2016 at 2:55

rekire · Accepted Answer · 2016-12-23 10:55:19Z

0

You need to intercept the callback for handling url clicks like this:

webView.setWebViewClient(new WebViewClient() {
    @Override
    public void onPageStarted(WebView view, String url, Bitmap favicon) {
        super.onPageStarted(view, url, favicon);
        shouldOverrideUrlLoading(view, Uri.parse(url));
    }

    @TargetApi(Build.VERSION_CODES.LOLLIPOP)
    @Override
    public boolean shouldOverrideUrlLoading(WebView view, WebResourceRequest request) {
        return shouldOverrideUrlLoading(view, request.getUrl());
    }

    // legacy callback
    @Override
    public boolean shouldOverrideUrlLoading(WebView view, String url) {
        if(Build.VERSION.SDK_INT < Build.VERSION_CODES.LOLLIPOP) {
            return shouldOverrideUrlLoading(view, Uri.parse(url));
        }
        return super.shouldOverrideUrlLoading(view, url);
    }

    private boolean shouldOverrideUrlLoading(final WebView view, final Uri request) {
        if(request.getScheme().equals("blob")) {
            // do your special handling for blob urls here
            return true;
        }
    }
});

In shouldOverrideUrlLoading() you can do your special handling.

answered Dec 23, 2016 at 10:55

rekire

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7 Comments

anon Over a year ago

Which type of special handling please specify? bdw shouldOverrideUrlLoading() is not called at all :-(

rekire Over a year ago

What do you want to do with that url?

rekire Over a year ago

try this special handling: webView.loadUrl(request.toString().substring(5));

rekire Over a year ago

How should the correct http address look like? I mean there is no official blob protocol.

Alexey Ozerov Over a year ago

shouldOverrideUrlLoading() isn't triggered at all for this download (tested with Webview 66)

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