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android – WebView Javascript cross domain from a local HTML file

Posted by: admin April 23, 2020 Leave a comment

Questions:

I load a local html file (from assets folder) to the app WebView.
In the HTML I run a jQuery.getJSON(url). the url is a remote server.

This action fails, and I’m guessing because of a different origin issue (cross domain). I run the same file on chrome and there it specifically says so.

Is there a way to allow the WebView in Android to load data from remote server on a local loaded HTML file?

How to&Answers:

Today morning I found solution that seems to be working.

The Java part

Initialize your WebView:

WebView _webView = (WebView) this.findViewById(R.id.id_of_your_webview_in_layout);

get WebView settings:

WebSettings settings = _webView.getSettings();

set following settings:

settings.setJavaScriptEnabled(true);
settings.setAllowFileAccessFromFileURLs(true); //Maybe you don't need this rule
settings.setAllowUniversalAccessFromFileURLs(true);

now you can load your your html file by standard way:

_webView.loadUrl("file:///android_asset/www/index.html");

The Javascript part

Create XHR request by standard way

var xhr = new XMLHttpRequest();
xhr.open("get", "http://google.com", false);
xhr.send();

Print the result somewhere

document.body.innerHTML = xhr.responseText

NOTICE:
This procedure works only on API level 16 or higher (At least the documentation says that).

Answer:

Don’t forget to add the internet permission in your manifest file:

<uses-permission android:name="android.permission.INTERNET"/>

Also make sure you are using JSONP requests (don’t forget the &callback=? as stated above)

Answer:

I load a local html file (from assets folder) to the app WebView

Note that you failed to say how you are doing this. I am going to guess that it was by a loadUrl() on a file:///android_asset URL.

Is there a way to allow the WebView in Android to load data from remote server on a local loaded HTML file?

Try using loadDataWithBaseURL() to load the content, supplying a URL on the remote server as the base URL.

Answer:

Ajax calls wont work from local file system. More over it will become cross-domain. So it wont work. It worked in eclipse, becuz you tried from local server.

Answer:

A solution we used was to use Android to get the update files from the server, place them and overwrite files in the web folder, and then browse.