Flutter使用JsBridge方式处理Webview与H5通信的方法

webview_flutter: 0.3.19+9

<uses-permission android:name="android.permission.INTERNET"/>

<key>io.flutter.embedded_views_preview</key>
<string>YES</string>

const WebView({
 Key key,
 this.onWebViewCreated,
 this.initialUrl,
 this.javascriptMode = JavascriptMode.disabled,
 this.javascriptChannels,
 this.navigationDelegate,
 this.gestureRecognizers,
 this.onPageStarted,
 this.onPageFinished,
 this.debuggingEnabled = false,
 this.gestureNavigationEnabled = false,
 this.userAgent,
 this.initialMediaPlaybackPolicy =
  AutoMediaPlaybackPolicy.require_user_action_for_all_media_types,
 }) : assert(javascriptMode != null),
  assert(initialMediaPlaybackPolicy != null),
  super(key: key);

<button onclick="callFlutter()">callFlutter</button>
function callFlutter(){
 Toast.postMessage("JS调用了Flutter"); 
}

WebView(
  javascriptChannels: <JavascriptChannel>[ 
  _alertJavascriptChannel(context),
 ].toSet(),
)

JavascriptChannel _alertJavascriptChannel(BuildContext context) {
 return JavascriptChannel(
  name: 'Toast',
  onMessageReceived: (JavascriptMessage message) {
  showToast(message.message);
  });
}

document.location = "js://webview?arg1=111&args2=222";

navigationDelegate: (NavigationRequest request) {
 if (request.url.startsWith('js://webview')) { 
 showToast('JS调用了Flutter By navigationDelegate'); 
 print('blocking navigation to $request}');
 Navigator.push(context,
  new MaterialPageRoute(builder: (context) => new testNav()));
 return NavigationDecision.prevent;
 }
 print('allowing navigation to $request');
 return NavigationDecision.navigate; //必须有
},

class JsBridge {
 String method; // 方法名
 Map data; // 传递数据
 Function success; // 执行成功回调
 Function error; // 执行失败回调

 JsBridge(this.method, this.data, this.success, this.error);

 /// jsonEncode方法中会调用实体类的这个方法。如果实体类中没有这个方法，会报错。
 Map toJson() {
 Map map = new Map();
 map["method"] = this.method;
 map["data"] = this.data;
 map["success"] = this.success;
 map["error"] = this.error;
 return map;
 }
 
 static JsBridge fromMap(Map<String, dynamic> map) {
 JsBridge jsonModel = new JsBridge(map['method'], map['data'], map['success'], map['error']);
 return jsonModel;
 }

 @override
 String toString() {
 return "JsBridge: {method: $method, data: $data, success: $success, error: $error}";
 }
}

class JsBridgeUtil {
 /// 将json字符串转化成对象
 static JsBridge parseJson(String jsonStr) {
 JsBridge jsBridgeModel = JsBridge.fromMap(jsonDecode(jsonStr));
 return jsBridgeModel;
 }

 /// 向H5开发接口调用
 static executeMethod(context, JsBridge jsBridge) async{
 if (jsBridge.method == 'openWeChatApp') {
  /// 先检测是否已安装微信
  bool _isWechatInstalled = await fluwx.isWeChatInstalled();
  if (!_isWechatInstalled) {
  toast.show(context, '您没有安装微信');
  jsBridge.error?.call();
  return;
  }
  fluwx.openWeChatApp();
  jsBridge.success?.call();
 }
 }
}

 final String url;
 final String title;
 WebViewController webViewController; // 添加一个controller
 final PrivacyProtocolDialog privacyProtocolDialog;

 Webview({Key key, this.url, this.title = '', this.privacyProtocolDialog})
  : super(key: key);

 @override
 WebViewState createState() => WebViewState();
}

class WebViewState extends State<Webview> {
 bool isPhone = Adapter.isPhone();
 JavascriptChannel _JsBridge(BuildContext context) => JavascriptChannel(
  name: 'FoxApp', // 与h5 端的一致 不然收不到消息
  onMessageReceived: (JavascriptMessage msg) async{
  String jsonStr = msg.message;
  JsBridgeUtil.executeMethod(JsBridgeUtil.parseJson(jsonStr));
  });

 @override
 Widget build(BuildContext context) {
 return Scaffold(
  backgroundColor: isPhone ? Colors.white : Color(Config.foxColors.bg),
  appBar: AppBar(
  backgroundColor: isPhone ? null : Color(Config.foxColors.bg),
  leading: AppIcon(Config.foxImages.backGreyUrl,
   callback: (){
    Navigator.of(context).pop(true);
    if (widget.privacyProtocolDialog != null) { // 解决切换页面时弹框显示异常问题
    privacyProtocolDialog.show(context);
    }
   }),
  title: Text(widget.title),
  centerTitle: true,
  elevation: 0,
  ),
  body: StoreConnector<AppState, UserState>(
   converter: (store) => store.state.userState,
   builder: (context, userState) {
   return WebView(
    initialUrl: widget.url,
    userAgent:"Mozilla/5.0 FoxApp", // h5 可以通过navigator.userAgent判断当前环境
    javascriptMode: JavascriptMode.unrestricted, // 启用 js交互，默认不启用JavascriptMode.disabled
    javascriptChannels: <JavascriptChannel>[
    _JsBridge(context) // 与h5 通信
    ].toSet(),
   );
   }),

 );
 }
}

<!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">
 <meta http-equiv="X-UA-Compatible" content="ie=edge">
 <title>Document</title>
</head>
<script src="https://cdn.bootcss.com/jquery/2.0.1/jquery.js"></script>
<body>
coming baby!
<script>
var str = navigator.userAgent;
if (str.includes('FoxApp')) {
FoxApp.postMessage(JSON.stringify({method:"openWeChatApp"}));
} else {
$('body').html('<p>hello world</p>');
}
</script>
</body>
</html>