flutter开发实战-inappwebview实现flutter与Javascript方法调用
在使用inappwebview时候,需要flutter端与JS进行交互,调用相应的方法,在inappwebview中的JavaScript Handlers。
一、JavaScript Handlers
要添加JavaScript Handlers,可以使用InAppWebViewController.addJavaScriptHandler方法,在该方法中定义handlerName和JavaScript端调用它时要调用的回调。回调可以返回要在JavaScript端发送的数据。如果您需要在加载网页后立即管理JavaScript处理程序,则应在创建InAppWebView时调用InAppWebViewController.addJavaScriptHandler。
以下是如何注册JavaScript处理程序的示例:
onWebViewCreated: (controller) {
// register a JavaScript handler with name "myHandlerName"
controller.addJavaScriptHandler(handlerName: 'myHandlerName', callback: (args) {
// print arguments coming from the JavaScript side!
print(args);
// return data to the JavaScript side!
return {
'bar': 'bar_value', 'baz': 'baz_value'
};
});
},
在JavaScript端,要执行回调处理程序并将数据发送到Flutter,您需要使用window.Flutter_inappwebview.callHandler(handlerName,…args)方法,其中handlerName是一个字符串,表示您正在调用的处理程序名称,args是可以发送到Fluter方面的可选参数。
注意:
如果相更换一个名字,我们可以更换一个名字来嵌套window.flutter_inappwebview
window.myCustomObj = { callHandler: window.flutter_inappwebview.callHandler } and, then, you can use window.myCustomObj.callHandler
此外,可以通过这种方式包装整个特定的处理代码:
const myHandlerName = (…args) => window.flutter_inappwebview.callHandler(‘myHandlerName’, …args);
然后调用myHandlerName();
在Javascript端,如果需要调用callHandler,需要监听flatterInAppWebViewPlatformReady。可以使用在flatterInAppWebViewPlatformReady事件被分派时设置的全局标志变量,并在调用window.flutter_inappwebview.callHandler方法之前使用它。
示例代码如下
// execute inside the "flutterInAppWebViewPlatformReady" event listener
window.addEventListener("flutterInAppWebViewPlatformReady", function(event) {
const args = [1, true, ['bar', 5], {foo: 'baz'}];
window.flutter_inappwebview.callHandler('myHandlerName', ...args);
});
// or using a global flag variable
var isFlutterInAppWebViewReady = false;
window.addEventListener("flutterInAppWebViewPlatformReady", function(event) {
isFlutterInAppWebViewReady = true;
});
// then, somewhere in your code
if (isFlutterInAppWebViewReady) {
const args = [1, true, ['bar', 5], {foo: 'baz'}];
window.flutter_inappwebview.callHandler('myHandlerName', ...args);
}
在flutter端,Flutter在执行注入方法时候,调用evaluateJavascript来执行callHandler,这个flutterInAppWebViewPlatformReady无需监听,因为这个flutterInAppWebViewPlatformReady已经Ready了。
可以在onLoadStop中调用代码
onLoadStop: (controller, url) async {
await controller.evaluateJavascript(source: """
const args = [1, true, ['bar', 5], {foo: 'baz'}];
window.flutter_inappwebview.callHandler('myHandlerName', ...args);
""");
},
window.flutter_inappwebview.callHandler返回一个JavaScript Promise,该Promise可用于获取回调返回的json结果。在这种情况下,只需返回您想要发送的数据,它将使用dart:convert库中的jsonEncode自动进行json编码。
一个简单的示例代码
import 'dart:async';
import 'dart:io';
import 'package:flutter/material.dart';
import 'package:flutter_inappwebview/flutter_inappwebview.dart';
Future main() async {
WidgetsFlutterBinding.ensureInitialized();
if (Platform.isAndroid) {
await AndroidInAppWebViewController.setWebContentsDebuggingEnabled(true);
}
runApp(new MyApp());
}
class MyApp extends StatefulWidget {
@override
_MyAppState createState() => new _MyAppState();
}
class _MyAppState extends State<MyApp> {
InAppWebViewGroupOptions options = InAppWebViewGroupOptions(
android: AndroidInAppWebViewOptions(
useHybridComposition: true,
),);
@override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
appBar: AppBar(title: Text("JavaScript Handlers")),
body: SafeArea(
child: Column(children: <Widget>[
Expanded(
child: InAppWebView(
initialData: InAppWebViewInitialData(
data: """
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
</head>
<body>
<h1>JavaScript Handlers</h1>
<script>
window.addEventListener("flutterInAppWebViewPlatformReady", function(event) {
window.flutter_inappwebview.callHandler('handlerFoo')
.then(function(result) {
// print to the console the data coming
// from the Flutter side.
console.log(JSON.stringify(result));
window.flutter_inappwebview
.callHandler('handlerFooWithArgs', 1, true, ['bar', 5], {foo: 'baz'}, result);
});
});
</script>
</body>
</html>
"""
),
initialOptions: options,
onWebViewCreated: (controller) {
controller.addJavaScriptHandler(handlerName: 'handlerFoo', callback: (args) {
// return data to the JavaScript side!
return {
'bar': 'bar_value', 'baz': 'baz_value'
};
});
controller.addJavaScriptHandler(handlerName: 'handlerFooWithArgs', callback: (args) {
print(args);
// it will print: [1, true, [bar, 5], {foo: baz}, {bar: bar_value, baz: baz_value}]
});
},
onConsoleMessage: (controller, consoleMessage) {
print(consoleMessage);
// it will print: {message: {"bar":"bar_value","baz":"baz_value"}, messageLevel: 1}
},
),
),
]))),
);
}
}
二、监听自定义CustomEvent
可以设置一个消息事件侦听器(与postMessage一起使用)或一个自定义事件侦听器。
// message event listener
window.addEventListener("message", (event) => {
console.log(event.data);
}, false);
// or custom event listener
window.addEventListener("myCustomEvent", (event) => {
console.log(event.detail);
}, false);
然后使用window.dispatch
// using postMessage method
window.postMessage({foo: 1, bar: false});
// or dispatching a custom event
const event = new CustomEvent("myCustomEvent", {
detail: {foo: 1, bar: false}
});
window.dispatchEvent(event);
因此,可以在运行时使用InAppWebViewController.eevaluatteJavascript方法或在web应用程序内部设置这些事件侦听器,并使用相同的方法调度这些事件。
例如:
onLoadStop: (controller, url) async {
await controller.evaluateJavascript(source: """
window.addEventListener("myCustomEvent", (event) => {
console.log(JSON.stringify(event.detail));
}, false);
""");
await Future.delayed(Duration(seconds: 5));
controller.evaluateJavascript(source: """
const event = new CustomEvent("myCustomEvent", {
detail: {foo: 1, bar: false}
});
window.dispatchEvent(event);
""");
},
onConsoleMessage: (controller, consoleMessage) {
print(consoleMessage);
// it will print: {message: {"foo":1,"bar":false}, messageLevel: 1}
},
三、小结
flutter开发实战-inappwebview实现flutter与Javascript方法调用。描述可能不是特别准确,请见谅。文章来源:https://www.toymoban.com/news/detail-773625.html
学习记录,每天不停进步。文章来源地址https://www.toymoban.com/news/detail-773625.html
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