Ну, вы можете достичь этого, как это
webView.setWebViewClient(new WebViewClient() {
@Override
public boolean shouldOverrideUrlLoading(WebView view, String url) {
if (url.equals("alert://alert")) {
Toast.makeText(this, "alert", Toast.LENGTH_LONG).show();
} else if (url.equals("choose://image")) {
Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
intent.addCategory(Intent.CATEGORY_OPENABLE);
intent.setType("image/*");
startActivityForResult(intent, FILECHOOSER_RESULTCODE);
}
return true;
}
});
и ваш HTML должен быть таким
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>Test Android Popup</title>
</head>
<body>
<label>Test Alert 1:</label>
<form action="alert://alert">
<input type="submit" value="Click me!">
</form>
<br>
<label>Test Browse file</label>
<form action="image://choose">
<input type="submit" value="Choose File">
</form>
</body>
</html>