I'm trying to integrate a javascript plugin that loads some resources by using XmlHttpRequest calls. I want this script to run within a locally loaded page in WebView. As you might have guessed already, XmlHttpRequest calls are not allowed for local resources, so I promptly get the following error:
XMLHttpRequest cannot load file:///android_asset/resources.html. Cross
origin requests are only supported for HTTP.
At this point I thought that I could emulate the web server by intercepting the calls and then just loading the file myself, such as:
webView.setWebViewClient(new WebViewClient() {
#Override
public WebResourceResponse shouldInterceptRequest(final WebView view, String url) {
try {
if (url.contains("resources.html")) { //breakpoint here is not triggering
return new WebResourceResponse("text/html", "UTF-8", getAssets().open("resources.html"));
}
} catch (IOException e) {
return super.shouldInterceptRequest(view, url);
}
return super.shouldInterceptRequest(view, url);
}
});
The problem is that shouldInterceptRequest is not being called. The official documentation is very brief and doesn't specify what type of requests are intercepted. This article sort of implies that the method does intercept XmlHttpRequest calls, but it doesn't appear to be working.
Does anyone know if shouldInterceptRequest should be called after a XmlHttpRequest? If not, is there another way to do this? Thanks
In API level 16 WebSettings added methods setAllowFileAccessFromFileURLs() and setAllowUniversalAccessFromFileURLs(). Setting this to true for the webView might solve your problem.
As my testing on this, it seems that only external requests would be intercepted - you can try to modify the local references to be external as "http://foo.com/..." (instead of "file:///android_asset/...").
Related
I have a hybrid application where I have a WebView which is implementing the shouldOverrideUrlLoading method (both the deprecated and the newest version). This should take over control before loading any external links or certain links within my domain. Without going into specifics, the code looks roughtly like this:
private WebView mWebView;
mWebView.setWebViewClient(new myWebViewClient() {
#Override
public boolean shouldOverrideUrlLoading(WebView view, String url) {
if(url.isExternal() || url.contains("#specialCase")) {
// Do actions
return true;
}
return super.shouldOverrideUrlLoading(view, url);
}
});
I have noticed that all external links work properly, however shouldOverrideUrlLoading is not being called at all when the link is within my domain, so there is no way for me to detect those cases where I want to take over control.
The android documentation states
Give the host application a chance to take over the control when a new
url is about to be loaded in the current WebView.
Does that new mean different domain? Is there anything I am missing or doing wrong? Any ideas on how to detect the user has clicked a link pointing to the same domain?
Thank you in advance.
Finally found the reason why shouldOverrideUrlLoading was never been called.
Apparently the method is only called when the actual loading is about to start. Our web application is a single-page application, hence even though the URL changes, no new page is loaded and shouldOverrideUrlLoading is not called.
I want to add custom Headers to requests in the webview. I think it should be possible to do it in shouldInterceptRequest.. Since my minimum API level is less than 21 shouldInterceptRequest (final WebView view, final String url) is also called and therefore I need to add headers here as well but I am not sure how.
#Override
public WebResourceResponse shouldInterceptRequest(WebView view, WebResourceRequest request) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
request.getRequestHeaders().put("ClientId", "ANDROID");
request.getRequestHeaders().put("Tokon", token);
}
return super.shouldInterceptRequest(view, request);
}
#Override
public WebResourceResponse shouldInterceptRequest(final WebView view, final String url) {
// I need to updated the header here
return super.shouldInterceptRequest(view, url);
}
There is a suggestion to use view.loadUrl(url,headers) but this does not work either.
The difficulty you run into with pre API 21 is the shouldInterceptRequest only provides the intercepted URL and the webview without the body of the request. I ran into this same issue and discovered the following GitHub repository
https://github.com/KeejOow/android-post-webview
The important part of this project is interceptheader.html in the assets folder. This html contains javascript that is inserted at the top of every html response the webview loads. This JS intercepts every form and ajax submission from the page and loads the body data into a java class. Next the shouldInterceptRequest method determines whether the request is POST or GET (you only get those two, unfortunately) based on whether there is any data in the body.
Finally, once it has marshalled all the relevant information, it performs the request by itself (instead of passing it off to Android), returning the resulting WebResourceResponse.
Be warned that the repository has seen some aging. I had to do some fiddling to get pages to work as I wanted them.
The best place to add your headers is in the InterceptingWebViewClient class under shouldInterceptRequest.
conn.setRequestProperty("header-name", value);
After looking around, I am unable to find an easy way to intercept requests made by the WebView and change the URL.
For example, I would like requests *.melange to actually route to localhost:8080 while keeping the original URL as the Host header.
It appears, at first glance, that the easiest method to achieve this sort of URL rewriting would be to use the "new" (API Level 21 or higher) shouldInterceptRequest, copy the values out of the WebResourceRequest to make the HTTP request manually then return a WebResourceResponse with the correct values. In my mind, there "should" be an easier way to do this.
Please let me know if I am missing something obvious. Thanks!
private class MyWebviewclient extends WebViewClient {
#Override
public boolean shouldOverrideUrlLoading(WebView view, String url) {
if(url.contains("melange"){
String newUrl = "http://localhost:8080"+url.split("melange")[1];
loadUrl(newUrl);
}
return false;
}
}
Now,
yourWebView.setWebViewClient(new MyWebviewclient());
I have an App that uses custom schemes in Android WebViewClient's shouldInterceptRequest(WebView view, String url) and shouldOverrideUrlLoading(WebView view, String url) to intercept requests in a web application and use a native library to fetch resources from elsewhere in shouldInterceptRequest. This has worked fine up until Android 4.4 KitKat, where Google has made some crucial changes to the webView component.
http://developer.android.com/guide/webapps/migrating.html#URLs
Now the url received in shouldOverrideUrlLoading suddenly gets invalid, looking like this; custom-scheme:////my.pathname.com/. First I suspected the extra slashes were because Android did not think the url were valid RFC3986, but in a series of resource fetches (css, js, images), the url starts off correct and suddenly changes to the invalid format. The webView in Android 4.3 kept the url correctly as custom-scheme://my.pathname.com/. It seems like the base url suddenly changes to '/' instead of 'my.pathname.com'.
Then my attention changed to the fact that the webView 4.4 migration guide talks about:
If you call methods on WebView from any thread other than your app's UI thread, it can cause unexpected results. http://developer.android.com/guide/webapps/migrating.html#Threads
This also might be what I am experiencing, but I have not yet come up with a solution where I can use runOnUiThread() to fetch data with the native api and return it to the webView inside shouldInterceptRequest. Has anyone experienced something similar?
Here is a simplified version of my shouldInterceptRequest code:
#Override
public WebResourceResponse shouldInterceptRequest(WebView view, String url) {
if (urlStartsWithKnownPrefix(url)) {
UrlFetchResult fetchRes = api.fetchUrl(url);
String charset = "utf-8";
String mime = fetchRes.getMimetype();
WebResourceResponse res = new WebResourceResponse(mime, charset, new ByteArrayInputStream(fetchRes.getResult()));
return res;
}
return null;
}
Are you using jquery-mobile by any chance? This sounds very similar to: How can I use relative urls in ajax requests within trigger.io apps on Android 4.4 (kitkat)?
I have a sharepoint site, which has ntlm authentication. in order for me to load the page, i do an authentication to the site using this.
public String LoadUrlWithNTLM(String url){
CkHttp http = new CkHttp();
http.put_Login("username");
http.put_Password("password");
http.put_NtlmAuth(true);
http.put_SessionLogFilename("ntlmAuthLog.txt");
String source = http.quickGetStr(url);
return source;
}
and load the webview with this.
public void LoadWebView(String url, String source){
webView = (WebView) findViewById(R.id.webView1);
webView.getSettings().setJavaScriptEnabled(true);
webView.setWebViewClient(new WebViewClient());
webView.loadDataWithBaseURL(url, source, "text/html", "", "");
}
i call this in the OnCreate()
source= LoadUrlWithNTLM(url);
LoadWebView(url,source);
then i check if there is a url event click with this
webView.setWebViewClient(new WebViewClient() {
public boolean shouldOverrideUrlLoading(WebView view, String url){
String toWebView = LoadUrlWithNTLM(url);
LoadWebView(url,source);
return false;
}
});
at some point, i can manage through go to the Sharepoint Site with NTLM Authentication, but when i click some link, it just display "401 UNAUTHORIZED" and do not invoke the shouldOverrideUrlLoading() method on breakpoint.
After authorizing, each subsequent HTTP request should include an Authorization header that contains the result of the prior authorization. If the subsequent request were sent using Chilkat HTTP, then the object would automatically send this Authorization header. However, the WebView has no knowledge of it, and it's including any Authorization header with it's request, and therefore you get the "401 Unauthorized" error.
One solution is to see if you can do NTLM authorization with WebView. I'm assuming you're using Chilkat only because this is not possible.
Another solution is to use Chilkat as you are doing, but then get the value of the Authorization header (from Chilkat) and explicitly set this header field with WebView. I don't know enough about WebView to know whether this is possible. To get the value of the Authorization header from Chilkat may require a new Chilkat feature (and I think this may be easy to do). (or it's already possible, but in a convoluted way)