Develop Reference

Android and custom URL scheme

I'm working on an app with a custom url scheme.
It is opening some webpage for authentication in a chrome tab. This is done in xamarin forms like this:
Browser.OpenAsync(apiUrl + "mobile", new BrowserLaunchOptions
{
LaunchMode = BrowserLaunchMode.SystemPreferred,
TitleMode = BrowserTitleMode.Hide,
});
everything work as expected if I return a webpage with a link and click the the link manually:
Click here to go the app
But if i return a 302 redirect to the same url it will not close the chrome tab and dont focus the app again.
If i add a javascript in the response, it will not automatically open the url (close the chrome tab and focus the app)
I've tried things like this:
window.location = url;
window.open(url,'_self');
setTimeout(()=>window.open(url,'_self'),10);
(url is a valid variable, even tried alert(url) after changing the location and it show the correct url.
Why does it only work when I click the link manually?

In order to maintain the user's security and experience, the browser prohibits the direct use of window.open(URL) in JS to open new links.
Try to change like below:
setTimeout(()=>window.open(url,'_self'),500); //The delay time must not be too short or you will be intercepted

How to get Webview 'url' from AccessibilityNodeInfo

Suppose ,I'm on the third party app say Amazon.
Now I'm able to access all of the window content using accessibility service and accessibility event type : typeViewFocused.
And I have a condition that if the window content contains class name android.webkit.WebView then I have to find the loaded URL for that Webview. But couldn't find the URL
, I can access all the content inside webview but I dont need the content of WebView I only need that URL which that webview used to load the content. Even I have checked all AccessibilityNodeInfo objects but not able to find URL

android webview form post

I want to write a form proxy in my app. The html file is stored locally and the form code is
<form action="custom" method="POST" />
My custom WebView should handle the action tag differently. So custom should be redirected to a different URL, depending on user settings in my app.
I wrote a custom WebView and where I override postUrl, but it is never fired. I also tried a custom WebViewClient and override shouldOverrideUrlLoading, but this is also not fired.
Which method should I override to change my post url and the CONTENT-TYPE for my formular?
Edit: I found https://code.google.com/p/android/issues/detail?id=9122 and I thing nobody found a solution for this problem. That's really bad.

Inject javascript into WebView right after the page is loaded and change action of the form using it. You can simply inject javascript by calling webView.loadUrl("javascript:...");

Android WebView (4.4) Converts Custom URL

I have an app that heavily uses the Android WebView to display my custom HTML content. The latest Android update (4.4/Kit-Kat/SDK-19) featured a redesigned WebView.
One of my users with a Nexus 5 reported a problem where some links cause the app to crash. I ran in the 4.4 emulator and debug into my WebViewClient's shouldOverrideUrlLoading() method. On all previously tested Android versions (2.2-4.3) the url String passed into the method had my custom url with "/" characters in it. In 4.4 the exact same link now has "\" characters in their place.
This doesn't make any sense to me. I load the HTML exactly the same, so somehow the new WebView converted all my slashes into backslashes.
Why does the new WebView do this?

Changes in URL handling are a known issue. Please see the migration guide for more detail.
The behaviour in this particular case will depend on what your base URL's scheme is, from what you're describing I'm guessing your base URL's scheme is "http(s)://" in which case the Chromium WebView performs URL normalization.
You might want to consider using the URI class to handle the discrepancy between the Classic and Chromium WebViews in this case.

I did more debugging and discovered I actually have the question reversed. Turns out the older versions of WebView did conversions of the URL, not the new one.
I load HTML with a format similar to this into a WebView:
link
I use the double back slashes as delimiters and parse the data later when the link is clicked. In older versions of WebView it converted my double backslash characters into forward slashes. It had been so long since I was in that code, I forgot I adjusted my code to use forward slashes rather than the backslashes in the original HTML.
The new version of WebView leaves my custom URL intact, giving me the exact same string as my original HTML. So turns out the old WebView is the problem not the new one.

The new WebView applies additional restrictions when requesting resources and resolving links that use a custom URL scheme. For example, if you implement callbacks such as shouldOverrideUrlLoading() or shouldInterceptRequest(), then WebView invokes them only for valid URLs.
If you are using a custom URL scheme or a base URL and notice that your app is receiving fewer calls to these callbacks or failing to load resources on Android 4.4, ensure that the requests specify valid URLs that conform to RFC 3986.
For example, the new WebView may not call your shouldOverrideUrlLoading() method for links like this:
Show Profile
The result of the user clicking such a link can vary:
If you loaded the page by calling loadData() or loadDataWithBaseURL() with an invalid or null base URL, then you will not receive the shouldOverrideUrlLoading() callback for this type of link on the page.
Note: When you use loadDataWithBaseURL() and the base URL is invalid or set null, all links in the content you are loading must be absolute.
If you loaded the page by calling loadUrl() or provided a valid base URL with loadDataWithBaseURL(), then you will receive the shouldOverrideUrlLoading() callback for this type of link on the page, but the URL you receive will be absolute, relative to the current page. For example, the URL you receive will be "http://www.example.com/showProfile" instead of just "showProfile".
Instead of using a simple string in a link as shown above, you can use a custom scheme such as the following:
Show Profile
You can then handle this URL in your shouldOverrideUrlLoading() method like this:
// The URL scheme should be non-hierarchical (no trailing slashes)
private static final String APP_SCHEME = "example-app:";
#Override
public boolean shouldOverrideUrlLoading(WebView view, String url) {
if (url.startsWith(APP_SCHEME)) {
urlData = URLDecoder.decode(url.substring(APP_SCHEME.length()), "UTF-8");
respondToData(urlData);
return true;
}
return false;
}
If you can't alter the HTML then you may be able to use loadDataWithBaseURL() and set a base URL consisting of a custom scheme and a valid host, such as "example-app:///". For example:
webView.loadDataWithBaseURL("example-app://example.co.uk/", HTML_DATA,
null, "UTF-8", null);
The valid host name should conform to RFC 3986 and it's important to include the trailing slash at the end, otherwise, any requests from the loaded page may be dropped.

to avoid webview below 4.4 convert backslash to forward slash, I just escape my url, then in Java code, use URI.decode to get the real url.That works for me.

page not available when opening link in webview

I take the response from an HTTP connection in the form of string and show that to webview like this:
WebView engine = (WebView)findViewById(R.id.webview);
engine.loadData(endResult, "text/html", "UTF-8"); /*endresult is string*/
I actually get a response that contains the google page (google search result direct from google.com).
The loadData method works well i.e it shows the web page but when I click on one of the links on that page it shows "page not available" and said that "xyz link might be temporarily down or it may have moved to permanently to a new web address".
this happens for all links accept the first present link on that page. i.e it shows correct page from first link on that page but fails for others..

I noticed that OSes prior to 2.3 failed to follow links if setHorizontalScrollBarEnabled and setVerticalScrollBarEnabled are set to false.

try to use loadDataWithBaseURL of the WebView class

I would avoid using engine.loadData - it seems to cause all sorts of crazy problems.
Use engine.loadDataWithBaseURL instead, and pass the base URL of where the content exists. I would think that the content you are loading is using relative paths in it's HTML so it's looking inside your app resources. By specifying the base URL you get around this problem.