Flutter如何从flutterWebviewPlugin.evalJavascript(addEventListener)中检索javascript值

本文介绍了Flutter如何从flutterWebviewPlugin.evalJavascript(addEventListener)中检索javascript值的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

我有一个浮动的代码段，用于侦听我的iframe页面中的postMessage.(flutter_webview_plugin:^ 0.3.9 + 1)

I have a flutter code snippet which listens for postMessage from my iframe page. (flutter_webview_plugin: ^0.3.9+1)

flutterWebviewPlugin.onStateChanged.listen((viewState) async {
    String script = 'window.addEventListener("message", receiveMessage, false);' +
            'function receiveMessage(event) {console.log(\'receiving data from child , data as follows: \',event.data)}';
    flutterWebviewPlugin.evalJavascript(script);
}

如果 event.data 返回特定值，我想触发特定的颤动功能，相机值将触发我的特定功能，该功能会调用相机插件，依此类推.意思是说我的目标iFrame将尝试通过 postMessage 方法进行跨域通信.

I would like to trigger specific flutter functions if event.data returns a specific value , camera value would trigger my specific function that calls the camera plugin and so on. Meaning to say that my target iFrame will attempt to do a cross-origin communication via postMessage method.

对于Cordova，我可以执行以下操作:

For Cordova, I could do something like this:

window.addEventListener( "message" , function( event )
{
  else if( event.data.indexOf( "camera" ) >= 0 )
        {
           //Trigger Camera Function

我该如何进行颤振?

推荐答案

为您提供2种解决方案:

2 solution for you:

解决方案1 :推荐

import 'package:flutter/material.dart';
import 'package:flutter_webview_plugin/flutter_webview_plugin.dart';

final Set<JavascriptChannel> jsChannels = [
  JavascriptChannel(
      name: 'Print',
      onMessageReceived: (JavascriptMessage message) {
        print('message.message: ${message.message}');
      }),
].toSet();

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      routes: {
        "/": (_) => WebviewScaffold(
              url: Uri.dataFromString(
                      '<html><button onclick="Print.postMessage(\'test\');">Click me</button></html>',
                      mimeType: 'text/html')
                  .toString(),
              appBar: new AppBar(title: new Text("Widget webview")),
              javascriptChannels: jsChannels,
            ),
      },
    );
  }
}

解决方案2 :如果要保留window.post. (也许您想在其他平台上使用iframe)

Solution 2: If you want to keep your window.post. (Maybe you would like to use the iframe from another platform)

import 'package:flutter/material.dart';
import 'package:flutter_webview_plugin/flutter_webview_plugin.dart';

final Set<JavascriptChannel> jsChannels = [
  JavascriptChannel(
      name: 'Print',
      onMessageReceived: (JavascriptMessage message) {
        print('message.message: ${message.message}');
      }),
].toSet();

void main() {
  final flutterWebviewPlugin = FlutterWebviewPlugin();
  flutterWebviewPlugin.onStateChanged.listen((state) async {
    if (state.type == WebViewState.finishLoad) {
      String script =
          'window.addEventListener("message", receiveMessage, false);' +
              'function receiveMessage(event) {Print.postMessage(event.data);}';
      flutterWebviewPlugin.evalJavascript(script);
    }
  });
  return runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      routes: {
        "/": (_) => WebviewScaffold(
              url: Uri.dataFromString(
                      '<html><button onclick="window.postMessage(\'test\', \'*\');">Click me</button></html>',
                      mimeType: 'text/html')
                  .toString(),
              appBar: new AppBar(title: new Text("Widget webview")),
              javascriptChannels: jsChannels,
            ),
      },
    );
  }
}

pubspec.yaml:

dependencies:
  flutter:
    sdk: flutter
  cupertino_icons: ^0.1.2
  flutter_webview_plugin: 0.3.9+1

参考:

https://github.com/fluttercommunity/flutter_webview_plugin/issues/309
https://github.com/fluttercommunity/flutter_webview_plugin/pull/457
https://github.com/fluttercommunity/flutter_webview_plugin/issues/364
https://github.com/fluttercommunity/flutter_webview_plugin/pull/523/files
https://github.com/fluttercommunity/flutter_webview_plugin/issues/305

https://github.com/fluttercommunity/flutter_webview_plugin/issues/309
https://github.com/fluttercommunity/flutter_webview_plugin/pull/457
https://github.com/fluttercommunity/flutter_webview_plugin/issues/364
https://github.com/fluttercommunity/flutter_webview_plugin/pull/523/files
https://github.com/fluttercommunity/flutter_webview_plugin/issues/305

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