[webview_flutter] Add onReceivedError callback

packages/webview_flutter/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 0.3.20
+
+* Added support for receiving web resource loading errors. See `WebView.onWebResourceError`.
+
 ## 0.3.19+10
 
 * Replace deprecated `getFlutterEngine` call on Android.

packages/webview_flutter/android/src/main/java/io/flutter/plugins/webviewflutter/FlutterWebViewClient.java

@@ -4,17 +4,21 @@
 
 package io.flutter.plugins.webviewflutter;
 
+import android.annotation.SuppressLint;
 import android.annotation.TargetApi;
 import android.graphics.Bitmap;
 import android.os.Build;
 import android.util.Log;
 import android.view.KeyEvent;
+import android.webkit.WebResourceError;
 import android.webkit.WebResourceRequest;
 import android.webkit.WebView;
 import android.webkit.WebViewClient;
+import androidx.webkit.WebResourceErrorCompat;
 import androidx.webkit.WebViewClientCompat;
 import io.flutter.plugin.common.MethodChannel;
 import java.util.HashMap;
+import java.util.Locale;
 import java.util.Map;
 
 // We need to use WebViewClientCompat to get
@@ -30,6 +34,47 @@ class FlutterWebViewClient {
     this.methodChannel = methodChannel;
   }
 
+  private static String errorCodeToString(int errorCode) {
+    switch (errorCode) {
+      case WebViewClient.ERROR_AUTHENTICATION:
+        return "authentication";
+      case WebViewClient.ERROR_BAD_URL:
+        return "badUrl";
+      case WebViewClient.ERROR_CONNECT:
+        return "connect";
+      case WebViewClient.ERROR_FAILED_SSL_HANDSHAKE:
+        return "failedSslHandshake";
+      case WebViewClient.ERROR_FILE:
+        return "file";
+      case WebViewClient.ERROR_FILE_NOT_FOUND:
+        return "fileNotFound";
+      case WebViewClient.ERROR_HOST_LOOKUP:
+        return "hostLookup";
+      case WebViewClient.ERROR_IO:
+        return "io";
+      case WebViewClient.ERROR_PROXY_AUTHENTICATION:
+        return "proxyAuthentication";
+      case WebViewClient.ERROR_REDIRECT_LOOP:
+        return "redirectLoop";
+      case WebViewClient.ERROR_TIMEOUT:
+        return "timeout";
+      case WebViewClient.ERROR_TOO_MANY_REQUESTS:
+        return "tooManyRequests";
+      case WebViewClient.ERROR_UNKNOWN:
+        return "unknown";
+      case WebViewClient.ERROR_UNSAFE_RESOURCE:
+        return "unsafeResource";
+      case WebViewClient.ERROR_UNSUPPORTED_AUTH_SCHEME:
+        return "unsupportedAuthScheme";
+      case WebViewClient.ERROR_UNSUPPORTED_SCHEME:
+        return "unsupportedScheme";
+    }
+
+    final String message =
+        String.format(Locale.getDefault(), "Could not find a string for errorCode: %d", errorCode);
+    throw new IllegalArgumentException(message);
+  }
+
   @TargetApi(Build.VERSION_CODES.LOLLIPOP)
   private boolean shouldOverrideUrlLoading(WebView view, WebResourceRequest request) {
     if (!hasNavigationDelegate) {
@@ -79,6 +124,14 @@ private void onPageFinished(WebView view, String url) {
     methodChannel.invokeMethod("onPageFinished", args);
   }
 
+  private void onWebResourceError(final int errorCode, final String description) {
+    final Map<String, Object> args = new HashMap<>();
+    args.put("errorCode", errorCode);
+    args.put("description", description);
+    args.put("errorType", FlutterWebViewClient.errorCodeToString(errorCode));
+    methodChannel.invokeMethod("onWebResourceError", args);
+  }
+
   private void notifyOnNavigationRequest(
       String url, Map<String, String> headers, WebView webview, boolean isMainFrame) {
     HashMap<String, Object> args = new HashMap<>();
@@ -123,6 +176,20 @@ public void onPageFinished(WebView view, String url) {
         FlutterWebViewClient.this.onPageFinished(view, url);
       }
 
+      @TargetApi(Build.VERSION_CODES.M)
+      @Override
+      public void onReceivedError(
+          WebView view, WebResourceRequest request, WebResourceError error) {
+        FlutterWebViewClient.this.onWebResourceError(
+            error.getErrorCode(), error.getDescription().toString());
+      }
+
+      @Override
+      public void onReceivedError(
+          WebView view, int errorCode, String description, String failingUrl) {
+        FlutterWebViewClient.this.onWebResourceError(errorCode, description);
+      }
+
       @Override
       public void onUnhandledKeyEvent(WebView view, KeyEvent event) {
         // Deliberately empty. Occasionally the webview will mark events as having failed to be
@@ -154,6 +221,22 @@ public void onPageFinished(WebView view, String url) {
         FlutterWebViewClient.this.onPageFinished(view, url);
       }
 
+      // This method is only called when the WebViewFeature.RECEIVE_WEB_RESOURCE_ERROR feature is
+      // enabled. The deprecated method is called when a device doesn't support this.
+      @SuppressLint("RequiresFeature")
+      @Override
+      public void onReceivedError(
+          WebView view, WebResourceRequest request, WebResourceErrorCompat error) {
+        FlutterWebViewClient.this.onWebResourceError(
+            error.getErrorCode(), error.getDescription().toString());
+      }
+
+      @Override
+      public void onReceivedError(
+          WebView view, int errorCode, String description, String failingUrl) {
+        FlutterWebViewClient.this.onWebResourceError(errorCode, description);
+      }
+
       @Override
       public void onUnhandledKeyEvent(WebView view, KeyEvent event) {
         // Deliberately empty. Occasionally the webview will mark events as having failed to be

packages/webview_flutter/example/test_driver/webview_flutter_e2e.dart

@@ -4,12 +4,14 @@
 
 import 'dart:async';
 import 'dart:convert';
+import 'dart:io';
 import 'dart:typed_data';
 
 import 'package:flutter/foundation.dart';
 import 'package:flutter/services.dart';
 import 'package:flutter/widgets.dart';
 import 'package:flutter_test/flutter_test.dart';
+import 'package:webview_flutter/platform_interface.dart';
 import 'package:webview_flutter/webview_flutter.dart';
 import 'package:e2e/e2e.dart';
 
@@ -576,6 +578,52 @@ void main() {
       expect(currentUrl, 'https://www.google.com/');
     });
 
+    testWidgets('onWebResourceError', (WidgetTester tester) async {
+      final Completer<WebResourceError> errorCompleter =
+          Completer<WebResourceError>();
+
+      await tester.pumpWidget(
+        Directionality(
+          textDirection: TextDirection.ltr,
+          child: WebView(
+            key: GlobalKey(),
+            initialUrl: 'https://www.notawebsite..com',
+            onWebResourceError: (WebResourceError error) {
+              errorCompleter.complete(error);
+            },
+          ),
+        ),
+      );
+
+      final WebResourceError error = await errorCompleter.future;
+      expect(error, isNotNull);
+
+      if (Platform.isIOS) expect(error.domain, isNotNull);
+      if (Platform.isAndroid) expect(error.errorType, isNotNull);
+    });
+
+    testWidgets('onWebResourceError is not called with valid url',
+        (WidgetTester tester) async {
+      final Completer<WebResourceError> errorCompleter =
+          Completer<WebResourceError>();
+
+      await tester.pumpWidget(
+        Directionality(
+          textDirection: TextDirection.ltr,
+          child: WebView(
+            key: GlobalKey(),
+            initialUrl:
+                'data:text/html;charset=utf-8;base64,PCFET0NUWVBFIGh0bWw+',
+            onWebResourceError: (WebResourceError error) {
+              errorCompleter.complete(error);
+            },
+          ),
+        ),
+      );
+
+      expect(errorCompleter.future, doesNotComplete);
+    });
+
     testWidgets('can block requests', (WidgetTester tester) async {
       final Completer<WebViewController> controllerCompleter =
           Completer<WebViewController>();

packages/webview_flutter/ios/Classes/FLTWKNavigationDelegate.m

@@ -5,10 +5,10 @@
 #import "FLTWKNavigationDelegate.h"
 
 @implementation FLTWKNavigationDelegate {
-  FlutterMethodChannel* _methodChannel;
+  FlutterMethodChannel *_methodChannel;
 }
 
-- (instancetype)initWithChannel:(FlutterMethodChannel*)channel {
+- (instancetype)initWithChannel:(FlutterMethodChannel *)channel {
   self = [super init];
   if (self) {
     _methodChannel = channel;
@@ -18,18 +18,18 @@ - (instancetype)initWithChannel:(FlutterMethodChannel*)channel {
 
 #pragma mark - WKNavigationDelegate conformance
 
-- (void)webView:(WKWebView*)webView didStartProvisionalNavigation:(WKNavigation*)navigation {
+- (void)webView:(WKWebView *)webView didStartProvisionalNavigation:(WKNavigation *)navigation {
   [_methodChannel invokeMethod:@"onPageStarted" arguments:@{@"url" : webView.URL.absoluteString}];
 }
 
-- (void)webView:(WKWebView*)webView
-    decidePolicyForNavigationAction:(WKNavigationAction*)navigationAction
+- (void)webView:(WKWebView *)webView
+    decidePolicyForNavigationAction:(WKNavigationAction *)navigationAction
                     decisionHandler:(void (^)(WKNavigationActionPolicy))decisionHandler {
   if (!self.hasDartNavigationDelegate) {
     decisionHandler(WKNavigationActionPolicyAllow);
     return;
   }
-  NSDictionary* arguments = @{
+  NSDictionary *arguments = @{
     @"url" : navigationAction.request.URL.absoluteString,
     @"isForMainFrame" : @(navigationAction.targetFrame.isMainFrame)
   };
@@ -56,13 +56,52 @@ - (void)webView:(WKWebView*)webView
                             decisionHandler(WKNavigationActionPolicyAllow);
                             return;
                           }
-                          NSNumber* typedResult = result;
+                          NSNumber *typedResult = result;
                           decisionHandler([typedResult boolValue] ? WKNavigationActionPolicyAllow
                                                                   : WKNavigationActionPolicyCancel);
                         }];
 }
 
-- (void)webView:(WKWebView*)webView didFinishNavigation:(WKNavigation*)navigation {
+- (void)webView:(WKWebView *)webView didFinishNavigation:(WKNavigation *)navigation {
   [_methodChannel invokeMethod:@"onPageFinished" arguments:@{@"url" : webView.URL.absoluteString}];
 }
+
++ (id)errorCodeToString:(NSUInteger)code {
+  switch (code) {
+    case WKErrorUnknown:
+      return @"unknown";
+    case WKErrorWebContentProcessTerminated:
+      return @"webContentProcessTerminated";
+    case WKErrorWebViewInvalidated:
+      return @"webViewInvalidated";
+    case WKErrorJavaScriptExceptionOccurred:
+      return @"javaScriptExceptionOccurred";
+    case WKErrorJavaScriptResultTypeIsUnsupported:
+      return @"javaScriptResultTypeIsUnsupported";
+  }
+
+  return [NSNull null];
+}
+
+- (void)onWebResourceError:(NSError *)error {
+  [_methodChannel invokeMethod:@"onWebResourceError"
+                     arguments:@{
+                       @"errorCode" : @(error.code),
+                       @"domain" : error.domain,
+                       @"description" : error.description,
+                       @"errorType" : [FLTWKNavigationDelegate errorCodeToString:error.code],
+                     }];
+}
+
+- (void)webView:(WKWebView *)webView
+    didFailNavigation:(WKNavigation *)navigation
+            withError:(NSError *)error {
+  [self onWebResourceError:error];
+}
+
+- (void)webView:(WKWebView *)webView
+    didFailProvisionalNavigation:(WKNavigation *)navigation
+                       withError:(NSError *)error {
+  [self onWebResourceError:error];
+}
 @end