Develop Reference

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.

Inject Content into WebView Before Loading Url

I have an app with a previously-existing, web-based registration process that I am trying to use inside a WebView. I need to add some style tags to the html in order to hide some elements for better displaying the content inside my app. I can get it to work on initial load, but I cannot figure out how to do it from one page to the next inside the WebView. Here is what I have working:
On initial load of the site, I am getting the raw html and appending "<style>MY STYLES HERE</style>" to the string before calling
wv.loadDataWithBaseURL(url, rawHtml, null, "UTF-8", url);
This works perfectly, but if a user clicks a link on the page and it loads another page into the WebView, then this code does not get called and the style tag is lost.
I assume I need to override "shouldOverrideUrlLoading" in the WebViewClient, but I don't know how to intercept the html from here. I thought I would try something like:
#Override
public boolean shouldOverrideUrlLoading(WebView view, String url) {
String rawHtml = getRawHtml(url) + "<style>...</style>";
wv.loadDataWithBaseURL(url, rawHtml, null, "UTF-8", url);
}
But this obviously sends it into an endless loop of intercepting the load to start a new load.
I have also tried overriding onPageFinished and doing:
wv.loadUrl("javascript:(function() { ... })()");
which works, except that it waits until the entire page is loaded before executing. This causes the page to appear loaded with all of the UI elements in tact, and then all of the ones I am trying to hide suddenly disappear. My ultimate goal is to enhance the look and feel of the site on a mobile device, so this is not an option.
Is there something else I can do in "shouldOverrideUrlLoading" to inject style tags? Or if not, what else can I try?

I've run into this problem, and depending on the number of redirects, etc, we have not been able to make the injected JavaScript available all the time.
At minimum, you should use the wv.loadUrl("javascript:(function() { ... })()"); approach, but call it in both onPageStarted() and onPageFinished().
Depending on the complexity of your pages, you might need to inject the JavaScript in onLoadResource() as well.

Android webview url redirect

I have a webview in my application which upon launch displays an html page. The page has a hyperlink which on click is supposed to display a video.
When i run the application and click on the video hyperlink link , nothing happens. But if i load the same page in android browser, then it launches a default video player and everything works fine.
I debugged it furthers by putting a log statement in shouldOverrideUrlLoading method and noticed that, when the hyperlink is clicked it gets redirected to another link and then to another link (final video streaming url).
My question is : why would the link work perfectly in default android browser and not through a webview.
Thanks

What is happening is when you click the hyperlink, that link probably has some popups inside of it. You need to define the onCreateWindow function in your webview's WebChromeClient. This handles how calls to open new windows or popups are handled.
public boolean onCreateWindow (WebView view, boolean dialog, boolean userGesture, Message resultMsg) {
((WebView.WebViewTransport) resultMsg.obj).setWebView(myWebView);
resultMsg.sendToTarget();
return true;
}

After declaring your WebView you should set javascript enabled, then your WebView will work as a browser.
For example:
WebView mwebview = new WebView(this);
setContentView(mwebview);
mwebview.getSettings().setJavaScriptEnabled(true);
or
mwebview.getSettings().setPluginState(PluginState.ON); // this is for newer API's

Basically, do not expect your embedded WebView works the same as Android default Browser. The default Browser is built on the same WebView, but there are lots a customization. (Especially around the no-standard uri, HTML5 stuff)
I followed code from here: WebView and HTML5 <video>, and I put the video link to a video tag, and I got the Video playing in my own version of WebView. The behavior is a little different from the default Browser. Given more time, we could figure that out by looking at its code, but anyways ...

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.