[webview_flutter] Implement loadRequest in Android package.

packages/webview_flutter/webview_flutter_android/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 2.5.0
+
+* Adds support for the `loadRequest` method from the platform interface.
+
 ## 2.4.0
 
 * Adds support for Android's `WebView.loadData` and `WebView.loadDataWithBaseUrl` methods and implements the `loadFile` and `loadHtmlString` methods from the platform interface.

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

@@ -185,6 +185,8 @@ 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);
@@ -407,6 +409,39 @@ 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:path_provider/path_provider.dart';
@@ -158,6 +159,7 @@ enum _MenuOptions {
   navigationDelegate,
   loadLocalFile,
   loadHtmlString,
+  doPostRequest,
 }
 
 class _SampleMenu extends StatelessWidget {
@@ -201,6 +203,9 @@ class _SampleMenu extends StatelessWidget {
               case _MenuOptions.loadHtmlString:
                 _onLoadHtmlStringExample(controller.data!, context);
                 break;
+              case _MenuOptions.doPostRequest:
+                _onDoPostRequest(controller.data!, context);
+                break;
             }
           },
           itemBuilder: (BuildContext context) => <PopupMenuItem<_MenuOptions>>[
@@ -241,6 +246,10 @@ class _SampleMenu extends StatelessWidget {
               value: _MenuOptions.loadLocalFile,
               child: Text('Load local file'),
             ),
+            const PopupMenuItem<_MenuOptions>(
+              value: _MenuOptions.doPostRequest,
+              child: Text('Post Request'),
+            ),
           ],
         );
       },
@@ -330,6 +339,17 @@ 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,
+      headers: <String, String>{'foo': 'bar', 'Content-Type': 'text/plain'},
+      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

@@ -402,6 +402,11 @@ 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 +2,8 @@
 // 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/foundation.dart';
 import 'package:flutter/widgets.dart' show AndroidViewSurface;
 
@@ -166,6 +168,13 @@ 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

@@ -3,9 +3,11 @@
 // found in the LICENSE file.
 
 import 'dart:async';
+import 'dart:io';
+import 'dart:typed_data';
 
 import 'package:flutter/widgets.dart';
-
+import 'package:http/http.dart' as http;
 import 'package:webview_flutter_platform_interface/webview_flutter_platform_interface.dart';
 
 import 'src/android_webview.dart' as android_webview;
@@ -120,6 +122,8 @@ class WebViewAndroidPlatformController extends WebViewPlatformController {
 
   late WebViewAndroidWebViewClient _webViewClient;
 
+  http.Client _httpClient = http.Client();
+
   /// Represents the WebView maintained by platform code.
   late final android_webview.WebView webView;
 
@@ -148,6 +152,12 @@ class WebViewAndroidPlatformController extends WebViewPlatformController {
   @visibleForTesting
   WebViewAndroidWebViewClient get webViewClient => _webViewClient;
 
+  /// Sets the HTTP client used for making requests on the dart side.
+  @visibleForTesting
+  set httpClient(http.Client httpClient) {
+    _httpClient = httpClient;
+  }
+
   @override
   Future<void> loadHtmlString(String html, {String? baseUrl}) {
     return webView.loadDataWithBaseUrl(
@@ -174,6 +184,46 @@ class WebViewAndroidPlatformController extends WebViewPlatformController {
     return webView.loadUrl(url, headers ?? <String, String>{});
   }
 
+  @override
+  Future<void> loadRequest(
+    WebViewRequest request,
+  ) async {
+    switch (request.method) {
+      case WebViewRequestMethod.get:
+        return loadUrl(request.uri.toString(), request.headers);
+      case WebViewRequestMethod.post:
+        // If the request requires no additional headers, postUrl can be used directly.
+        if (request.headers.isEmpty) {
+          return webView.postUrl(
+              request.uri.toString(), request.body ?? Uint8List(0));
+        }
+        // Otherwise, the request has to be made manually.
+        else {
+          final HTTPResponseWithUrl responseWithUrl =
+              await postUrlAndFollowRedirects(
+            request.uri,
+            headers: request.headers,
+            body: request.body ?? Uint8List(0),
+          );
+          final http.Response response = responseWithUrl.response;
+
+          final String baseUrl = responseWithUrl.url;
+          final String mimeType =
+              response.headers['content-type'] ?? 'text/html';
+
+          return webView.loadDataWithBaseUrl(
+            data: response.body,
+            baseUrl: baseUrl,
+            mimeType: mimeType,
+          );
+        }
+      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();
 
@@ -282,6 +332,46 @@ class WebViewAndroidPlatformController extends WebViewPlatformController {
 
   Future<void> _dispose() => webView.release();
 
+  // The http package currently does not expose the resulting url when
+  // automatically following redirects. Because of this, redirects have to be
+  // followed manually so that the final url can be tracked. Once this
+  // functionality has been implemented in the http package, this method
+  // should be removed.
+  // https://github.com/dart-lang/http/issues/556
+  // https://github.com/dart-lang/http/issues/293
+  /// Makes a POST request and automatically follows any redirections
+  /// while keeping track of the new location. Returns the final response
+  /// together with the url of the final redirection.
+  /// This method is only publicly visible for testing purposes.
+  @visibleForTesting
+  Future<HTTPResponseWithUrl> postUrlAndFollowRedirects(Uri uri,
+      {Map<String, String>? headers,
+      Uint8List? body,
+      int redirections = 0}) async {
+    final http.Request req = http.Request('POST', uri)
+      ..followRedirects = false
+      ..bodyBytes = body ?? <int>[];
+    req.headers.addAll(headers ?? <String, String>{});
+    final http.Response response =
+        await http.Response.fromStream(await _httpClient.send(req));
+
+    // If it's a redirection, follow it.
+    if (response.statusCode >= 300 &&
+        response.statusCode < 400 &&
+        response.headers.containsKey('location')) {
+      redirections++;
+      // Maximum of 20 redirections (Default in Chrome & Firefox).
+      if (redirections >= 20) {
+        throw const HttpException('Maximum amount of redirections reached.');
+      }
+      final Uri redirectUri = Uri.parse(response.headers['location']!);
+      return postUrlAndFollowRedirects(redirectUri,
+          headers: headers, body: body, redirections: redirections);
+    }
+
+    return HTTPResponseWithUrl(response, uri.toString());
+  }
+
   void _setCreationParams(CreationParams creationParams) {
     final WebSettings? webSettings = creationParams.webSettings;
     if (webSettings != null) {
@@ -636,3 +726,17 @@ class WebViewProxy {
     return android_webview.WebView.setWebContentsDebuggingEnabled(true);
   }
 }
+
+/// Wrapper class for bundling a http response with the url it came from.
+/// This class is only publicly visible for testing purposes.
+@visibleForTesting
+class HTTPResponseWithUrl {
+  /// Constructs a [HTTPResponseWithUrl].
+  HTTPResponseWithUrl(this.response, this.url);
+
+  /// The response object.
+  final http.Response response;
+
+  /// The url the response came from.
+  final String url;
+}

packages/webview_flutter/webview_flutter_android/pigeons/android_webview.dart

@@ -46,6 +46,12 @@ abstract class WebViewHostApi {
     Map<String, String> headers,
   );
 
+  void postUrl(
+    int instanceId,
+    String url,
+    Uint8List data,
+  );
+
   String getUrl(int instanceId);
 
   bool canGoBack(int instanceId);