[webview_flutter] Android implementation of loadFile and loadHtmlString methods

packages/webview_flutter/webview_flutter_android/CHANGELOG.md

@@ -1,5 +1,6 @@
-## NEXT
+## 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.
 * Updates to webview_flutter_platform_interface version 1.5.2.
 
 ## 2.3.1

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

@@ -173,6 +173,16 @@ public interface WebViewHostApi {
 
     void dispose(Long instanceId);
 
+    void loadData(Long instanceId, String data, String mimeType, String encoding);
+
+    void loadDataWithBaseUrl(
+        Long instanceId,
+        String baseUrl,
+        String data,
+        String mimeType,
+        String encoding,
+        String historyUrl);
+
     void loadUrl(Long instanceId, String url, Map<String, String> headers);
 
     String getUrl(Long instanceId);
@@ -274,6 +284,96 @@ static void setup(BinaryMessenger binaryMessenger, WebViewHostApi api) {
           channel.setMessageHandler(null);
         }
       }
+      {
+        BasicMessageChannel<Object> channel =
+            new BasicMessageChannel<>(
+                binaryMessenger, "dev.flutter.pigeon.WebViewHostApi.loadData", 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 dataArg = (String) args.get(1);
+                  if (dataArg == null) {
+                    throw new NullPointerException("dataArg unexpectedly null.");
+                  }
+                  String mimeTypeArg = (String) args.get(2);
+                  if (mimeTypeArg == null) {
+                    throw new NullPointerException("mimeTypeArg unexpectedly null.");
+                  }
+                  String encodingArg = (String) args.get(3);
+                  if (encodingArg == null) {
+                    throw new NullPointerException("encodingArg unexpectedly null.");
+                  }
+                  api.loadData(instanceIdArg.longValue(), dataArg, mimeTypeArg, encodingArg);
+                  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<>(
+                binaryMessenger,
+                "dev.flutter.pigeon.WebViewHostApi.loadDataWithBaseUrl",
+                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 baseUrlArg = (String) args.get(1);
+                  if (baseUrlArg == null) {
+                    throw new NullPointerException("baseUrlArg unexpectedly null.");
+                  }
+                  String dataArg = (String) args.get(2);
+                  if (dataArg == null) {
+                    throw new NullPointerException("dataArg unexpectedly null.");
+                  }
+                  String mimeTypeArg = (String) args.get(3);
+                  if (mimeTypeArg == null) {
+                    throw new NullPointerException("mimeTypeArg unexpectedly null.");
+                  }
+                  String encodingArg = (String) args.get(4);
+                  if (encodingArg == null) {
+                    throw new NullPointerException("encodingArg unexpectedly null.");
+                  }
+                  String historyUrlArg = (String) args.get(5);
+                  if (historyUrlArg == null) {
+                    throw new NullPointerException("historyUrlArg unexpectedly null.");
+                  }
+                  api.loadDataWithBaseUrl(
+                      instanceIdArg.longValue(),
+                      baseUrlArg,
+                      dataArg,
+                      mimeTypeArg,
+                      encodingArg,
+                      historyUrlArg);
+                  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

@@ -352,6 +352,30 @@ public void dispose(Long instanceId) {
     }
   }
 
+  @Override
+  public void loadData(Long instanceId, String data, String mimeType, String encoding) {
+    final WebView webView = (WebView) instanceManager.getInstance(instanceId);
+    webView.loadData(
+        data, parseNullStringIdentifier(mimeType), parseNullStringIdentifier(encoding));
+  }
+
+  @Override
+  public void loadDataWithBaseUrl(
+      Long instanceId,
+      String baseUrl,
+      String data,
+      String mimeType,
+      String encoding,
+      String historyUrl) {
+    final WebView webView = (WebView) instanceManager.getInstance(instanceId);
+    webView.loadDataWithBaseURL(
+        parseNullStringIdentifier(baseUrl),
+        data,
+        parseNullStringIdentifier(mimeType),
+        parseNullStringIdentifier(encoding),
+        parseNullStringIdentifier(historyUrl));
+  }
+
   @Override
   public void loadUrl(Long instanceId, String url, Map<String, String> headers) {
     final WebView webView = (WebView) instanceManager.getInstance(instanceId);
@@ -477,4 +501,13 @@ public void setWebChromeClient(Long instanceId, Long clientInstanceId) {
     final WebView webView = (WebView) instanceManager.getInstance(instanceId);
     webView.setWebChromeClient((WebChromeClient) instanceManager.getInstance(clientInstanceId));
   }
+
+  @Nullable
+  private static String parseNullStringIdentifier(String value) {
+    if (value.equals(nullStringIdentifier)) {
+      return null;
+    }
+
+    return value;
+  }
 }

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

@@ -156,6 +156,52 @@ public void releaseInputAwareWebViewDependents() {
     verify(mockJavaScriptChannel2).release();
   }
 
+  @Test
+  public void loadData() {
+    testHostApiImpl.loadData(
+        0L, "VGhpcyBkYXRhIGlzIGJhc2U2NCBlbmNvZGVkLg==", "text/plain", "base64");
+    verify(mockWebView)
+        .loadData("VGhpcyBkYXRhIGlzIGJhc2U2NCBlbmNvZGVkLg==", "text/plain", "base64");
+  }
+
+  @Test
+  public void loadDataWithNullValues() {
+    testHostApiImpl.loadData(
+        0L, "VGhpcyBkYXRhIGlzIGJhc2U2NCBlbmNvZGVkLg==", "<null-value>", "<null-value>");
+    verify(mockWebView).loadData("VGhpcyBkYXRhIGlzIGJhc2U2NCBlbmNvZGVkLg==", null, null);
+  }
+
+  @Test
+  public void loadDataWithBaseUrl() {
+    testHostApiImpl.loadDataWithBaseUrl(
+        0L,
+        "https://flutter.dev",
+        "VGhpcyBkYXRhIGlzIGJhc2U2NCBlbmNvZGVkLg==",
+        "text/plain",
+        "base64",
+        "about:blank");
+    verify(mockWebView)
+        .loadDataWithBaseURL(
+            "https://flutter.dev",
+            "VGhpcyBkYXRhIGlzIGJhc2U2NCBlbmNvZGVkLg==",
+            "text/plain",
+            "base64",
+            "about:blank");
+  }
+
+  @Test
+  public void loadDataWithBaseUrlAndNullValues() {
+    testHostApiImpl.loadDataWithBaseUrl(
+        0L,
+        "<null-value>",
+        "VGhpcyBkYXRhIGlzIGJhc2U2NCBlbmNvZGVkLg==",
+        "<null-value>",
+        "<null-value>",
+        "<null-value>");
+    verify(mockWebView)
+        .loadDataWithBaseURL(null, "VGhpcyBkYXRhIGlzIGJhc2U2NCBlbmNvZGVkLg==", null, null, null);
+  }
+
   @Test
   public void loadUrl() {
     testHostApiImpl.loadUrl(0L, "https://www.google.com", new HashMap<>());

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

@@ -6,8 +6,10 @@
 
 import 'dart:async';
 import 'dart:convert';
+import 'dart:io';
 import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
+import 'package:path_provider/path_provider.dart';
 import 'package:webview_flutter_android/webview_surface_android.dart';
 import 'package:webview_flutter_platform_interface/webview_flutter_platform_interface.dart';
 
@@ -38,6 +40,25 @@ The navigation delegate is set to block navigation to the youtube website.
 </html>
 ''';
 
+const String kExamplePage = '''
+<!DOCTYPE html>
+<html lang="en">
+<head>
+<title>Load file or HTML string example</title>
+</head>
+<body>
+
+<h1>Local demo page</h1>
+<p>
+  This is an example page used to demonstrate how to load a local file or HTML 
+  string using the <a href="https://pub.dev/packages/webview_flutter">Flutter 
+  webview</a> plugin.
+</p>
+
+</body>
+</html>
+''';
+
 class _WebViewExample extends StatefulWidget {
   const _WebViewExample({Key? key}) : super(key: key);
 
@@ -135,6 +156,8 @@ enum _MenuOptions {
   listCache,
   clearCache,
   navigationDelegate,
+  loadLocalFile,
+  loadHtmlString,
 }
 
 class _SampleMenu extends StatelessWidget {
@@ -172,6 +195,12 @@ class _SampleMenu extends StatelessWidget {
               case _MenuOptions.navigationDelegate:
                 _onNavigationDelegateExample(controller.data!, context);
                 break;
+              case _MenuOptions.loadLocalFile:
+                _onLoadLocalFileExample(controller.data!, context);
+                break;
+              case _MenuOptions.loadHtmlString:
+                _onLoadHtmlStringExample(controller.data!, context);
+                break;
             }
           },
           itemBuilder: (BuildContext context) => <PopupMenuItem<_MenuOptions>>[
@@ -204,6 +233,14 @@ class _SampleMenu extends StatelessWidget {
               value: _MenuOptions.navigationDelegate,
               child: Text('Navigation Delegate example'),
             ),
+            const PopupMenuItem<_MenuOptions>(
+              value: _MenuOptions.loadHtmlString,
+              child: Text('Load HTML string'),
+            ),
+            const PopupMenuItem<_MenuOptions>(
+              value: _MenuOptions.loadLocalFile,
+              child: Text('Load local file'),
+            ),
           ],
         );
       },
@@ -281,6 +318,18 @@ class _SampleMenu extends StatelessWidget {
     await controller.loadUrl('data:text/html;base64,$contentBase64');
   }
 
+  Future<void> _onLoadLocalFileExample(
+      WebViewController controller, BuildContext context) async {
+    final String pathToIndex = await _prepareLocalFile();
+
+    await controller.loadFile(pathToIndex);
+  }
+
+  Future<void> _onLoadHtmlStringExample(
+      WebViewController controller, BuildContext context) async {
+    await controller.loadHtmlString(kExamplePage);
+  }
+
   Widget _getCookieList(String cookies) {
     if (cookies == null || cookies == '""') {
       return Container();
@@ -294,6 +343,16 @@ class _SampleMenu extends StatelessWidget {
       children: cookieWidgets.toList(),
     );
   }
+
+  static Future<String> _prepareLocalFile() async {
+    final String tmpDir = (await getTemporaryDirectory()).path;
+    final File indexFile = File('$tmpDir/www/index.html');
+
+    await Directory('$tmpDir/www').create(recursive: true);
+    await indexFile.writeAsString(kExamplePage);
+
+    return indexFile.path;
+  }
 }
 
 class _NavigationControls extends StatelessWidget {

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

@@ -363,6 +363,28 @@ class WebViewController {
 
   WebView _widget;
 
+  /// Loads the file located on the specified [absoluteFilePath].
+  ///
+  /// The [absoluteFilePath] parameter should contain the absolute path to the
+  /// file as it is stored on the device. For example:
+  /// `/Users/username/Documents/www/index.html`.
+  ///
+  /// Throws an ArgumentError if the [absoluteFilePath] does not exist.
+  Future<void> loadFile(String absoluteFilePath) {
+    return _webViewPlatformController.loadFile(absoluteFilePath);
+  }
+
+  /// Loads the supplied HTML string.
+  ///
+  /// The [baseUrl] parameter is used when resolving relative URLs within the
+  /// HTML string.
+  Future<void> loadHtmlString(String html, {String? baseUrl}) {
+    return _webViewPlatformController.loadHtmlString(
+      html,
+      baseUrl: baseUrl,
+    );
+  }
+
   /// Loads the specified URL.
   ///
   /// If `headers` is not null and the URL is an HTTP URL, the key value paris in `headers` will

packages/webview_flutter/webview_flutter_android/example/pubspec.yaml

@@ -8,6 +8,9 @@ environment:
 dependencies:
   flutter:
     sdk: flutter
+
+  path_provider: ^2.0.6
+
   webview_flutter_android:
     # When depending on this package from a real application you should use:
     #   webview_flutter: ^x.y.z