Detailed explanation of the method of implementing interactive Webview in Flutter

1. Introduce the webview_flutter plugin

To use Webview in Flutter applications, you need to first introduce the webview_flutter plugin. The following dependencies can be added to the file:

dependencies:
  flutter:
    sdk: flutter
  webview_flutter: ^2.0.0

Then run the flutter packages get command to get the plugin.

2. Create a Webview Part

In Flutter applications, use the Webview component to display web content. We can create a simple Webview part using the following code:

import 'package:webview_flutter/webview_flutter.dart';
class MyWebview extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Webview example'),
      ),
      body: WebView(
        initialUrl: '',
      ),
    );
  }
}

The above code creates a Scaffold part that contains an AppBar and a Webview part. The initialUrl property of the Webview component is used to specify the initial URL to be loaded.

3. Add interactive functions

To implement interaction with Webview, you can use some of the methods provided in the webview_flutter plugin. For example, we can use the evaluateJavascript method to execute JavaScript code and communicate with the web page through JavaScriptChannels. The following code shows how to add a JavaScriptChannel to the Webview:

class MyWebview extends StatefulWidget {
  @override
  _MyWebviewState createState() => _MyWebviewState();
}
class _MyWebviewState extends State<MyWebview> {
  WebViewController _controller;
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Webview example'),
      ),
      body: WebView(
        initialUrl: '',
        javascriptMode: ,
        onWebViewCreated: (WebViewController controller) {
          _controller = controller;
          _controller.addJavascriptChannel(
              JavascriptChannel(
                name: 'MyChannel',
                onMessageReceived: (JavascriptMessage message) {
                  String data = ;
                  // Perform related operations                },
              ),
          );
        },
      ),
    );
  }
}

The above code creates a WebViewController object in the onWebViewCreated property of the WebView component, and adds a JavaScriptChannel called "MyChannel" to the WebViewController through the addJavascriptChannel method. In JavaScript, we can access this channel and send messages.

4. Send a message between Dart code and JavaScript

To send messages between Dart code and JavaScript, you can communicate using WebViewController and JavaScriptChannel respectively. The following example shows how to send messages to JavaScript in Dart code and receive and process these messages in JavaScript:

RaisedButton(
  onPressed: () {
    _controller.evaluateJavascript("('Hello from Flutter!')");
  },
  child: Text('Send a message to Webview'),
),

JavaScript code example:

 = function(message) {
  // Process the received message  (message);
}

In the above code, when the user clicks the button, the Dart code will send a message to the Webview through the evaluateJavascript method. In JavaScript, we use the postMessage function to receive this message and can view it in the console.

in conclusion

By introducing the webview_flutter plugin and using WebViewController and JavaScriptChannel, we can implement interactive Webviews in Flutter applications. In this way, we can more conveniently display web content for users and implement interactive functions with web pages. Hope this article can help you understand and apply Webview interaction in Flutter.

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