Develop Reference

WebViewClient return data to Activity onPageFinished

I need to collect browser cookies from a WebView and return them to another Activity. Collecting the cookies works already but happens within a class that extends WebViewClient, and I don't know how to return the data from there.
There are 2 Activities; MainActivity and LoginActivity, respectively. MainActivity has a single button that creates an Intent and starts LoginActivity, which has a single WebView. OnCreate(), the WebView is directed to the login page of a website. When the user successfully logs into this site, it stores data in the browser cookies - data that I need for an API call later. How can I return this data to MainActivity?
The WebView has a custom WebViewClient with an overridden OnPageFinished() method, which if the URL is the one expected, will collect the browser cookies, as shown below.
class TempWebViewClient extends WebViewClient {
#Override
public void onPageFinished(WebView view, String url) {
// If page URL is the Home page (ie., you logged in successfully), collect cookies.
if (url.equals("https://slate.sheridancollege.ca/d2l/m/home")) {
String cookies = CookieManager.getInstance().getCookie(url);
String[] cookies2 = cookies.split(";");
String key1 = "";
String key2 = "";
// Find Keys placed in browser cookies.
for (String c : cookies2) {
String[] c2 = c.split("=");
if (c2[0].equals(" phrase1")) {
key1 = c2[1];
}
if (c2[0].equals(" phrase2")) {
key = c2[1];
}
}
}
}
}
LoginActivity should not call finish() (returning to MainActivity) until I've received the keys from the cookies. How can I achieve this, given what I have already? I don't know how LoginActivity can hold off returning to MainActivity until it has the data from its WebView.
public class LoginActivty extends Activity {
WebView webview;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
setupViews();
setContentView(webview);
}
public void setupViews() {
StrictMode.ThreadPolicy policy = new
StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);
CookieManager.getInstance().setAcceptCookie(true);
webview = new WebView(this);
webview.setWebViewClient(new TempWebViewClient());
webview.getSettings().setJavaScriptEnabled(true);
webview.loadUrl("website");
}
}

Create reference of login activity in TempWebclient to pass the result once you get your cookie.
class TempWebViewClient extends WebViewClient {
LoginActivty mDelegate;
public TempWebViewClient(LoginActivty ref) {
this.mDelegate = ref;
}
#Override
public void onPageFinished(WebView view, String url) {
// perform task
String cookie;// get from CookieManager
mDelegate.sendCookieAndFinish(cookie);
}
}
Create function in your login activity
public class LoginActivty extends Activity {
WebView webview;
#Override
protected void onCreate(Bundle savedInstanceState) {
....
}
public void setupViews() {
....
// send activity reference to webclient
webview.setWebViewClient(new TempWebViewClient(this));
}
public void sendCookieAndFinish(String cookie){
setResult(ResultCode,ResultIntent); // set result for your main activity
// store cookie to storage
finish();
}
}
From Main Activity start your LoginActivity for result

How can I access a WebView in my Activity from Application class without memory leak?

I feel like the answer should be obvious but I can't find it. How do I reference a WebView in my main activity from Application class? Using a public static var to hold a reference to it in Activity class is causing a memory leak.
Current code (works, but causes memory leak).
Activity
public class Core extends AppCompatActivity {
public static WebView coreView;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_core);
WebView myWebView = (WebView) findViewById(R.id.webview);
WebSettings webSettings = myWebView.getSettings();
webSettings.setJavaScriptEnabled(true);
webSettings.setDomStorageEnabled(true);
webSettings.setJavaScriptCanOpenWindowsAutomatically(true);
myWebView.setWebViewClient(new WebViewClient());
myWebView.setPadding(0,80,0,0);
coreView = myWebView;
}
}
Application
public class App extends Application {
#Override
public void onCreate() {
super.onCreate();
Core.coreView.loadUrl("http://www.google.com");
}
EDIT:
Full App class.
public class App extends Application {
#Override
public void onCreate() {
super.onCreate();
OneSignal.startInit(this)
.inFocusDisplaying(OneSignal.OSInFocusDisplayOption.Notification)
.setNotificationOpenedHandler(new MainNotificationOpenedHandler())
.setNotificationReceivedHandler(new MainNotificationReceivedHandler())
.unsubscribeWhenNotificationsAreDisabled(true)
.init();
OSPermissionSubscriptionState status = OneSignal.getPermissionSubscriptionState();
}
private class MainNotificationOpenedHandler implements OneSignal.NotificationOpenedHandler {
// This fires when a notification is opened by tapping on it.
#Override
public void notificationOpened(OSNotificationOpenResult result) {
OSNotificationAction.ActionType actionType = result.action.type;
JSONObject data = result.notification.payload.additionalData;
String customKey;
Core.coreView.loadUrl(result.notification.payload.launchURL);
}
}
private class MainNotificationReceivedHandler implements OneSignal.NotificationReceivedHandler {
#Override
public void notificationReceived(OSNotification notification) {
JSONObject data = notification.payload.additionalData;
}
}
}

How do I reference a WebView in my main activity from Application class?
You don't. You move that code into the activity, or something scoped to that activity (e.g., a fragment).
For example, your code in your question is guaranteed to crash, as Core.coreView will not be set by the time onCreate() of an Application is called. onCreate() of an Application is called before any components, such as an activity, are created, as part of your process starting.

The method addJavascriptInterface(WebViewActivity.JavaScriptInterface, String) is undefined for the type CordovaWebView

I am not able to open link in Cordova webview on HTML button click. It shows "The method addJavascriptInterface(WebViewActivity.JavaScriptInterface, String) is undefined for the type CordovaWebView"
public class WebViewActivity extends CordovaActivity{
JavaScriptInterface JSInterface;
CordovaWebView mainView;
#SuppressLint("SetJavaScriptEnabled") public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
super.init();
setContentView(R.layout.webview);
mainView = (CordovaWebView) findViewById(R.id.webView1);
JavaScriptInterface jsInterface = new JavaScriptInterface(this);
mainView.getSettings().setJavaScriptEnabled(true);
mainView.addJavascriptInterface(jsInterface, "JSInterface");
System.out.println("Opening webview");
mainView.loadUrl("file:///android_asset/index.html" );
}
public class JavaScriptInterface {
Context mContext;
/** Instantiate the interface and set the context */
JavaScriptInterface(Context c) {
mContext = c;
}
public void changeActivity()
{
Log.d("In webviewActivity", "Inside change activity");
Intent i = new Intent(WebViewActivity.this, Google.class);
startActivity(i);
Log.d("After Intent", "Opening google class");
finish();
}
}
}

what version of cordova are you using?
I had the same problem with cordova 5.1, I recommend you to see this answer:
Accessing appView from Cordova 5.0.0
There you can see the method to access to your appview object and add the javascriptinterface.
Hope It helps!

Android - Call method from main class within JavaScriptInterface

I'm relatively new to android development and I'm trying to make a WebView that will allow me to launch the android camera app. How can I go about calling a method in the main class from with my JavaScriptInterface?
Thanks.
public class MainActivity extends Activity {
public static final int MEDIA_TYPE_IMAGE = 1888;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
WebView mainWebView = (WebView) findViewById(R.id.mainWebView);
mainWebView.addJavascriptInterface(new JavaScriptInterface(this), "Android");
WebSettings webSettings = mainWebView.getSettings();
webSettings.setJavaScriptEnabled(true);
mainWebView.setWebViewClient(new MyCustomWebViewClient());
//mainWebView.setScrollBarStyle(View.SCROLLBARS_INSIDE_OVERLAY);
mainWebView.loadUrl("file:///mnt/sdcard/page.html");
}
private class MyCustomWebViewClient extends WebViewClient {
#Override
public boolean shouldOverrideUrlLoading(WebView view, String url) {
view.loadUrl(url);
return true;
}
}
public void takePicture() {
Intent intent = new Intent(android.provider.MediaStore.ACTION_IMAGE_CAPTURE);
startActivityForResult(intent, MEDIA_TYPE_IMAGE);
}
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode == MEDIA_TYPE_IMAGE) {
Bitmap photo = (Bitmap) data.getExtras().get("data");
ByteArrayOutputStream stream = new ByteArrayOutputStream();
photo.compress(Bitmap.CompressFormat.PNG, 100, stream);
byte[] byteArray = stream.toByteArray();
}}
}
package com.cargowise.view;
import android.content.Context;
import android.os.Handler;
import android.widget.Toast;
public class JavaScriptInterface {
Context mContext;
/** Instantiate the interface and set the context */
JavaScriptInterface(Context c) {
mContext = c;
}
public void takePic() {
MainActivity.takePicture();
}
public void showToast(String toast) {
Toast.makeText(mContext, toast, Toast.LENGTH_SHORT).show();
}

You have stored the context which you should be able to use to access your MainActivity.
Change this:
public void takePic() {
MainActivity.takePicture();
}
To this:
public void takePic() {
((MainActivity)mContext).takePicture();
}
Note: you might want to add some type-checking or limit the type of the context that is given to a MainActivity to enforce correct behavior.

The suggestion of calling ((MainActivity)mContext).takePicture() is (probably) wrong, at least for me it failed. The reason is that the call will be not on the main/UI thread, but rather on some another thread.
Also, you MUST put the #JavascriptInterface annotation before each interface method.
The right way to place calls to main UI thread, which in turn will be able to do everything as usual on that thread, is this:
...inside JavaScriptInterface class
public void takePic() {
((MainActivity)mContext).post(new Runnable() {
#Override
public void run() {
((MainActivity)mContext).takePicture();
}
});
}
In Kotlin it would look much simpler:
#JavascriptInterface
fun takePic() {
(mContext as MainActivity).mainWebView?.post {
(mContext as MainActivity).takePicture()
}
}
Full example of integration of WebView with Android backend, with calls bak and forth between JS and Android, is here: https://github.com/latitov/Android_WebViewApp_FullScreen

sharing "Global" variables across activities, problem when using a Webview...?

I'm sharing some variables accross activities by using a class like this :
public class Globals {
static Boolean hint1_graph_type_switcher;
static Boolean hint2_stockview_valuation;
other variables ...
}
then I'm using these variables anywhere across my multiple activites with ...
if (Globals.hint2_stockview_valuation == false) {
....
}
pretty basic and it was working fine untill ...
I introduced some webview stuff like this:
//-----------------------------------------------------------
// open a webview with the NEWS when the more_arrow is clicked :
mNews.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
String news_URL = "http://us.m.yahoo.com/w/yfinance/symbolheadlines/"+ ticker + "/?.intl=us&.lang=en";
Intent news_Webview_intent = new Intent(Chart_View.this, News_Webview.class);
news_Webview_intent.putExtra("NEWS_URL", news_URL);
startActivity(news_Webview_intent);
}
});
//-----------------------------------------------------------
and here's the News_Webview.class:
public class News_Webview extends Activity {
//
// http://www.chrisdanielson.com/tag/progressdialog/
//
String news_URL;
private WebView webview;
private ProgressDialog progressBar;
private static final String TAG = "Hub";
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
setContentView(R.layout.webview_news);
this.webview = (WebView)findViewById(R.id.webView);
Bundle extras = getIntent().getExtras();
if (this.getIntent().getExtras()!=null){
news_URL = extras.getString("NEWS_URL");
}
WebSettings settings = webview.getSettings();
settings.setJavaScriptEnabled(true);
webview.setScrollBarStyle(WebView.SCROLLBARS_OUTSIDE_OVERLAY);
final AlertDialog alertDialog = new AlertDialog.Builder(this).create();
progressBar = ProgressDialog.show(News_Webview.this, "", "Loading...");
webview.setWebViewClient(new WebViewClient() {
public boolean shouldOverrideUrlLoading(WebView view, String url) {
//Log.i(TAG, "Processing webview url click...");
Intent viewIntent = new Intent("android.intent.action.VIEW", Uri.parse(url));
startActivity(viewIntent);
return true;
}
public void onPageFinished(WebView view, String url) {
//Log.i(TAG, "Finished loading URL: " +url);
if (progressBar.isShowing()) {
progressBar.dismiss();
}
}
public void onReceivedError(WebView view, int errorCode, String description, String failingUrl) {
Log.e(TAG, "Error: " + description);
Toast.makeText(News_Webview.this, "Oh no! " + description, Toast.LENGTH_SHORT).show();
alertDialog.setTitle("Error");
alertDialog.setMessage(description);
alertDialog.setButton("OK", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
return;
}
});
alertDialog.show();
}
});
webview.loadUrl(news_URL);
}
}
the problem now is that, when it "comes back" from this Activity, it looks like my Globals variables have disappeared ???
if (Globals.hint2_stockview_valuation == false) {
fires an error :
06-23 12:14:03.443:
ERROR/AndroidRuntime(2611): Caused by:
java.lang.NullPointerException
2 questions then :
Should I use something else than this "Global" class to share variables across activities ? Is it just bad practice to do this ?? I know that I can use the preferences but I thought it was quicker to do it this way (no need to "read" the preferences everytime I start a new activity ...
Any idea on WHY this is happening ? Should I "get back" my savedInstanceState in some way when my activity returns from the News_Webview.class ???
As always, thank you for your help.
H.

U could use intent.putExtra() for inter-activity interaction...
One thing(just for diagnostics) i would suggest is initializing the static variables to some value and then run the App... i suppose your global class is getting re-initialized when the intent started activity returns back...
I have used global variables, but in my case i kept them in an activity which never died. All other activities came after it and it worked perfectly fine...

The NullPointerException is bubbling up from the android runtime and has nothing to do with your Globals type.