Here’s another Android WebView tutorial for those of you who are looking for a way to get the source code of a page loaded in a WebView instance.
This example is a bit more complicated than previous ones, so let me explain it step by step:
- First, a class called MyJavaScriptInterface is defined. It implements a single public method showHTML() which displays a dialog with the HTML it receives as a parameter.
- Then, an instance of this class is registered as a JavaScript interface called HTMLOUT. The showHTML() method can now be accessed from JavaScript like this: window.HTMLOUT.showHTML(‘…’)
- In order to call showHTML() when the page finishes loading, a WebViewClient instance which overrides onPageFinished() is added to the WebView. When the page finises loading, this method will inject a piece of JavaScript code into the page, using the method I described in an earlier post.
- Finally, a web page is loaded.
final Context myApp = this;
/* An instance of this class will be registered as a JavaScript interface */
class MyJavaScriptInterface
{
@SuppressWarnings("unused")
public void showHTML(String html)
{
new AlertDialog.Builder(myApp)
.setTitle("HTML")
.setMessage(html)
.setPositiveButton(android.R.string.ok, null)
.setCancelable(false)
.create()
.show();
}
}
final WebView browser = (WebView)findViewById(R.id.browser);
/* JavaScript must be enabled if you want it to work, obviously */
browser.getSettings().setJavaScriptEnabled(true);
/* Register a new JavaScript interface called HTMLOUT */
browser.addJavascriptInterface(new MyJavaScriptInterface(), "HTMLOUT");
/* WebViewClient must be set BEFORE calling loadUrl! */
browser.setWebViewClient(new WebViewClient() {
@Override
public void onPageFinished(WebView view, String url)
{
/* This call inject JavaScript into the page which just finished loading. */
browser.loadUrl("javascript:window.HTMLOUT.showHTML('<head>'+document.getElementsByTagName('html')[0].innerHTML+'</head>');");
}
});
/* load a web page */
browser.loadUrl("http://lexandera.com/files/jsexamples/gethtml.html");
WARNING
Unfortunately, this approach suffers from a major security hole: if your JavaScript can call showHTML(), then so can JavaScript from every other page that might get loaded into the WebView. Use with care.
![Reblog this post [with Zemanta]](http://img.zemanta.com/reblog_e.png?x-id=bb22593d-ec9d-4064-9842-2bcb7fae4d4f)
Related posts:
