[webview_flutter] Implement loadRequest in Android package. (flutter#4563)

Implements the `loadRequest` method added in flutter#4450 for the Android package.

Related issue:
- flutter/flutter#27730

Author: BeMacized

packages/webview_flutter/webview_flutter_android/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 2.7.0
+
+* Adds support for the `loadRequest` method from the platform interface.
+
 ## 2.6.0
 
 * Adds implementation of the `loadFlutterAsset` method from the platform interface.

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

@@ -186,6 +186,8 @@ void loadDataWithBaseUrl(
 
     void loadUrl(Long instanceId, String url, Map<String, String> headers);
 
+    void postUrl(Long instanceId, String url, byte[] data);
+
     String getUrl(Long instanceId);
 
     Boolean canGoBack(Long instanceId);
@@ -410,6 +412,39 @@ static void setup(BinaryMessenger binaryMessenger, WebViewHostApi api) {
           channel.setMessageHandler(null);
         }
       }
+      {
+        BasicMessageChannel<Object> channel =
+            new BasicMessageChannel<>(
+                binaryMessenger, "dev.flutter.pigeon.WebViewHostApi.postUrl", getCodec());
+        if (api != null) {
+          channel.setMessageHandler(
+              (message, reply) -> {
+                Map<String, Object> wrapped = new HashMap<>();
+                try {
+                  ArrayList<Object> args = (ArrayList<Object>) message;
+                  Number instanceIdArg = (Number) args.get(0);
+                  if (instanceIdArg == null) {
+                    throw new NullPointerException("instanceIdArg unexpectedly null.");
+                  }
+                  String urlArg = (String) args.get(1);
+                  if (urlArg == null) {
+                    throw new NullPointerException("urlArg unexpectedly null.");
+                  }
+                  byte[] dataArg = (byte[]) args.get(2);
+                  if (dataArg == null) {
+                    throw new NullPointerException("dataArg unexpectedly null.");
+                  }
+                  api.postUrl(instanceIdArg.longValue(), urlArg, dataArg);
+                  wrapped.put("result", null);
+                } catch (Error | RuntimeException exception) {
+                  wrapped.put("error", wrapError(exception));
+                }
+                reply.reply(wrapped);
+              });
+        } else {
+          channel.setMessageHandler(null);
+        }
+      }
       {
         BasicMessageChannel<Object> channel =
             new BasicMessageChannel<>(

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

@@ -382,6 +382,12 @@ public void loadUrl(Long instanceId, String url, Map<String, String> headers) {
     webView.loadUrl(url, headers);
   }
 
+  @Override
+  public void postUrl(Long instanceId, String url, byte[] data) {
+    final WebView webView = (WebView) instanceManager.getInstance(instanceId);
+    webView.postUrl(url, data);
+  }
+
   @Override
   public String getUrl(Long instanceId) {
     final WebView webView = (WebView) instanceManager.getInstance(instanceId);

packages/webview_flutter/webview_flutter_android/android/src/test/java/io/flutter/plugins/webviewflutter/WebViewTest.java

@@ -208,6 +208,12 @@ public void loadUrl() {
     verify(mockWebView).loadUrl("https://www.google.com", new HashMap<>());
   }
 
+  @Test
+  public void postUrl() {
+    testHostApiImpl.postUrl(0L, "https://www.google.com", new byte[] {0x01, 0x02});
+    verify(mockWebView).postUrl("https://www.google.com", new byte[] {0x01, 0x02});
+  }
+
   @Test
   public void getUrl() {
     when(mockWebView.getUrl()).thenReturn("https://www.google.com");

packages/webview_flutter/webview_flutter_android/example/lib/main.dart

@@ -7,6 +7,7 @@
 import 'dart:async';
 import 'dart:convert';
 import 'dart:io';
+import 'dart:typed_data';
 import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_driver/driver_extension.dart';
@@ -189,6 +190,7 @@ enum _MenuOptions {
   loadLocalFile,
   loadHtmlString,
   transparentBackground,
+  doPostRequest,
 }
 
 class _SampleMenu extends StatelessWidget {
@@ -239,6 +241,9 @@ class _SampleMenu extends StatelessWidget {
               case _MenuOptions.transparentBackground:
                 _onTransparentBackground(controller.data!, context);
                 break;
+              case _MenuOptions.doPostRequest:
+                _onDoPostRequest(controller.data!, context);
+                break;
             }
           },
           itemBuilder: (BuildContext context) => <PopupMenuItem<_MenuOptions>>[
@@ -288,6 +293,10 @@ class _SampleMenu extends StatelessWidget {
               value: _MenuOptions.transparentBackground,
               child: Text('Transparent background example'),
             ),
+            const PopupMenuItem<_MenuOptions>(
+              value: _MenuOptions.doPostRequest,
+              child: Text('Post Request'),
+            ),
           ],
         );
       },
@@ -382,6 +391,16 @@ class _SampleMenu extends StatelessWidget {
     await controller.loadHtmlString(kExamplePage);
   }
 
+  Future<void> _onDoPostRequest(
+      WebViewController controller, BuildContext context) async {
+    final WebViewRequest request = WebViewRequest(
+      uri: Uri.parse('https://httpbin.org/post'),
+      method: WebViewRequestMethod.post,
+      body: Uint8List.fromList('Test Body'.codeUnits),
+    );
+    await controller.loadRequest(request);
+  }
+
   Widget _getCookieList(String cookies) {
     if (cookies == null || cookies == '""') {
       return Container();

packages/webview_flutter/webview_flutter_android/example/lib/web_view.dart

@@ -418,6 +418,11 @@ class WebViewController {
     return _webViewPlatformController.loadUrl(url, headers);
   }
 
+  /// Loads a page by making the specified request.
+  Future<void> loadRequest(WebViewRequest request) async {
+    return _webViewPlatformController.loadRequest(request);
+  }
+
   /// Accessor to the current URL that the WebView is displaying.
   ///
   /// If [WebView.initialUrl] was never specified, returns `null`.

packages/webview_flutter/webview_flutter_android/lib/src/android_webview.dart

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'dart:typed_data';
 import 'dart:ui';
 
 import 'package:flutter/foundation.dart';
@@ -169,6 +170,13 @@ class WebView {
     return api.loadUrlFromInstance(this, url, headers);
   }
 
+  /// Loads the URL with postData using "POST" method into this WebView.
+  ///
+  /// If url is not a network URL, it will be loaded with [loadUrl] instead, ignoring the postData param.
+  Future<void> postUrl(String url, Uint8List data) {
+    return api.postUrlFromInstance(this, url, data);
+  }
+
   /// Gets the URL for the current page.
   ///
   /// This is not always the same as the URL passed to

packages/webview_flutter/webview_flutter_android/lib/src/android_webview.pigeon.dart

@@ -220,6 +220,33 @@ class WebViewHostApi {
     }
   }
 
+  Future<void> postUrl(
+      int arg_instanceId, String arg_url, Uint8List arg_data) async {
+    final BasicMessageChannel<Object?> channel = BasicMessageChannel<Object?>(
+        'dev.flutter.pigeon.WebViewHostApi.postUrl', codec,
+        binaryMessenger: _binaryMessenger);
+    final Map<Object?, Object?>? replyMap =
+        await channel.send(<Object>[arg_instanceId, arg_url, arg_data])
+            as Map<Object?, Object?>?;
+    if (replyMap == null) {
+      throw PlatformException(
+        code: 'channel-error',
+        message: 'Unable to establish connection on channel.',
+        details: null,
+      );
+    } else if (replyMap['error'] != null) {
+      final Map<Object?, Object?> error =
+          (replyMap['error'] as Map<Object?, Object?>?)!;
+      throw PlatformException(
+        code: (error['code'] as String?)!,
+        message: error['message'] as String?,
+        details: error['details'],
+      );
+    } else {
+      return;
+    }
+  }
+
   Future<String> getUrl(int arg_instanceId) async {
     final BasicMessageChannel<Object?> channel = BasicMessageChannel<Object?>(
         'dev.flutter.pigeon.WebViewHostApi.getUrl', codec,

packages/webview_flutter/webview_flutter_android/lib/src/android_webview_api_impls.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'dart:typed_data';
+
 import 'package:flutter/services.dart';
 
 import 'android_webview.dart';
@@ -152,6 +154,15 @@ class WebViewHostApiImpl extends WebViewHostApi {
     return loadUrl(instanceManager.getInstanceId(instance)!, url, headers);
   }
 
+  /// Helper method to convert instances ids to objects.
+  Future<void> postUrlFromInstance(
+    WebView instance,
+    String url,
+    Uint8List data,
+  ) {
+    return postUrl(instanceManager.getInstanceId(instance)!, url, data);
+  }
+
   /// Helper method to convert instances ids to objects.
   Future<String> getUrlFromInstance(WebView instance) {
     return getUrl(instanceManager.getInstanceId(instance)!);

packages/webview_flutter/webview_flutter_android/lib/webview_android_widget.dart

@@ -3,6 +3,7 @@
 // found in the LICENSE file.
 
 import 'dart:async';
+import 'dart:typed_data';
 
 import 'package:flutter/widgets.dart';
 import 'package:webview_flutter_platform_interface/webview_flutter_platform_interface.dart';
@@ -210,6 +211,28 @@ class WebViewAndroidPlatformController extends WebViewPlatformController {
     return webView.loadUrl(url, headers ?? <String, String>{});
   }
 
+  /// When making a POST request, headers are ignored. As a workaround, make
+  /// the request manually and load the response data using [loadHTMLString].
+  @override
+  Future<void> loadRequest(
+    WebViewRequest request,
+  ) async {
+    if (!request.uri.hasScheme) {
+      throw ArgumentError('WebViewRequest#uri is required to have a scheme.');
+    }
+    switch (request.method) {
+      case WebViewRequestMethod.get:
+        return webView.loadUrl(request.uri.toString(), request.headers);
+      case WebViewRequestMethod.post:
+        return webView.postUrl(
+            request.uri.toString(), request.body ?? Uint8List(0));
+      default:
+        throw UnimplementedError(
+          'This version of webview_android_widget currently has no implementation for HTTP method ${request.method.serialize()} in loadRequest.',
+        );
+    }
+  }
+
   @override
   Future<String?> currentUrl() => webView.getUrl();