load startpage from offline container instead of simplay reloading, to avoid deadlocks on bad links

Author: xtools-at

app/src/main/java/at/xtools/pwawrapper/ui/UIManager.java

@@ -37,7 +37,7 @@ public UIManager(Activity activity) {
         offlineContainer.setOnClickListener(new View.OnClickListener() {
             @Override
             public void onClick(View v) {
-                webView.reload();
+                webView.loadUrl(Constants.WEBAPP_URL);
                 setOffline(false);
             }
         });

app/src/main/java/at/xtools/pwawrapper/webview/WebViewHelper.java

@@ -2,14 +2,17 @@
 
 import android.annotation.TargetApi;
 import android.app.Activity;
+import android.app.AlertDialog;
 import android.content.Context;
 import android.content.Intent;
 import android.graphics.Bitmap;
 import android.net.ConnectivityManager;
 import android.net.NetworkInfo;
 import android.net.Uri;
 import android.os.Build;
+import android.os.Handler;
 import android.os.Message;
+import android.util.Log;
 import android.webkit.CookieManager;
 import android.webkit.WebChromeClient;
 import android.webkit.WebResourceError;
@@ -140,37 +143,32 @@ public void onProgressChanged(WebView view, int newProgress) {
         webView.setWebViewClient(new WebViewClient() {
             @Override
             public void onPageStarted(WebView view, String url, Bitmap favicon) {
-                // prevent loading content that isn't ours
-                if (!url.startsWith(Constants.WEBAPP_URL)) {
-                    // stop loading
-                    view.stopLoading();
-
-                    // open external URL in Browser/3rd party apps instead
-                    Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse(url));
-                    activity.startActivity(intent);
-                }
-                // activate loading animation screen
-                uiManager.setLoading(true);
                 super.onPageStarted(view, url, favicon);
+                Log.d("TAG", "started url: "+url);
+                handleUrlLoad(view, url);
             }
 
             // handle loading error by showing the offline screen
             @Deprecated
             @Override
             public void onReceivedError(WebView view, int errorCode, String description, String failingUrl) {
+                Log.d("TAG", "receivedError Old");
                 if (Build.VERSION.SDK_INT < Build.VERSION_CODES.M) {
-                    uiManager.setOffline(true);
+                    handleLoadError(view, failingUrl, errorCode);
                 }
             }
 
             @TargetApi(Build.VERSION_CODES.M)
             @Override
             public void onReceivedError(WebView view, WebResourceRequest request, WebResourceError error) {
+                Log.d("TAG", "receivedError New");
                 if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
                     // new API method calls this on every error for each resource.
                     // we only want to interfere if the page itself got problems.
-                    if (view.getUrl().equals(request.getUrl().toString())) {
-                        uiManager.setOffline(true);
+                    String url = request.getUrl().toString();
+                    if (view.getUrl().equals(url)) {
+                        Log.d("TAG", "receivedError New page match " + error.getDescription().toString());
+                        handleLoadError(view, url, error.getErrorCode());
                     }
                 }
             }
@@ -186,6 +184,67 @@ public void onResume() {
         webView.onResume();
     }
 
+    // show "no app found" dialog
+    private void showNoAppDialog(Activity thisActivity) {
+        new AlertDialog.Builder(thisActivity)
+            .setTitle(R.string.noapp_heading)
+            .setMessage(R.string.noapp_description)
+            .show();
+    }
+    // handle load errors
+    private void handleLoadError(WebView view, String url, int errorCode) {
+        if (errorCode != WebViewClient.ERROR_UNSUPPORTED_SCHEME) {
+            uiManager.setOffline(true);
+        } else {
+            Log.d("TAG", "unsupported scheme!");
+            // Unsupported Scheme, recover
+            new Handler().postDelayed(new Runnable() {
+                @Override
+                public void run() {
+                    goBack();
+                }
+            }, 100);
+        }
+    }
+
+    // handle external urls
+    private boolean handleUrlLoad(WebView view, String url) {
+        // prevent loading content that isn't ours
+        if (!url.startsWith(Constants.WEBAPP_URL)) {
+            // stop loading
+            view.stopLoading();
+
+            /*
+            // handle non-http protocols, like mailto: or whatsapp:
+            if (!url.startsWith("http")) {
+                // this hit the WebView's onReceivedError callback, recover
+                goBack();
+                uiManager.setOffline(false);
+            }
+            */
+
+            // open external URL in Browser/3rd party apps instead
+            try {
+                Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse(url));
+                if (intent.resolveActivity(activity.getPackageManager()) != null) {
+                    activity.startActivity(intent);
+                } else {
+                    showNoAppDialog(activity);
+                }
+            } catch (Exception e) {
+                showNoAppDialog(activity);
+            }
+            // return value for shouldOverrideUrlLoading
+            return true;
+        } else {
+            // let WebView load the page!
+            // activate loading animation screen
+            uiManager.setLoading(true);
+            // return value for shouldOverrideUrlLoading
+            return false;
+        }
+    }
+
     // handle back button press
     public boolean goBack() {
         if (webView.canGoBack()) {

app/src/main/res/values-de/strings.xml

@@ -1,4 +1,6 @@
 <resources>
     <string name="offline_heading">Keine Internetverbindung.</string>
     <string name="offline_description">Hier tippen um es erneut zu versuchen!</string>
+    <string name="noapp_heading">Keine App gefunden.</string>
+    <string name="noapp_description">Keine App auf diesem Gerät kann die gewählte Aktion ausführen.</string>
 </resources>

app/src/main/res/values-en/strings.xml

@@ -1,4 +1,6 @@
 <resources>
     <string name="offline_heading">You are offline.</string>
     <string name="offline_description">Tap here to retry!</string>
+    <string name="noapp_heading">App not found.</string>
+    <string name="noapp_description">No App on this device can carry out this action.</string>
 </resources>

app/src/main/res/values/strings.xml

@@ -2,4 +2,6 @@
     <string name="app_name" translatable="false">Leasing Rechner</string>
     <string name="offline_heading">You are offline.</string>
     <string name="offline_description">Tap here to retry!</string>
+    <string name="noapp_heading">App not found.</string>
+    <string name="noapp_description">No App on this device can carry out this action.</string>
 </resources>