Flutter嵌入原生View，使用原生的WebView

悠悠 2023-10-09 13:48 110阅读 0赞

在Flutter开发过程中，我们发现Flutter对于WebView的支持并不太好，而我们原生项目中，使用的腾讯的X5 WebView，所以也想在Flutter中进行嵌入使用。  
具体的操作步骤如下

#### Android端 ####

新建`FlutterWebView`，继承自`PlatformView`

class FlutterWebView(
        val context: Context,
        val messenger: BinaryMessenger,
        val viewId: Int,
        val args: Map<String, Any>?
    ) : PlatformView, MethodChannel.MethodCallHandler {
        
        private var webView: WebView? = null
    
        override fun getView(): View {
        
        	//curAct在Application.ActivityLifecycleCallbacks中进行注入
            val curAct = App.getApp().curActivity
            webView = WebView(curAct)
            //..... 这里可以进行webView的一些配置
            
            if (args != null) {
        
                val url = args["url"] as String
                webView!!.loadUrl(url)
            } else {
        
                throw IllegalArgumentException("args is null.")
            }
            return webView!!
        }
    
        override fun dispose() {
        
            webView?.destroy()
        }
    }

新建`FlutterWebViewFactory`，继承自`PlatformViewFactory`

class FlutterWebViewFactory(val messenger: BinaryMessenger) : PlatformViewFactory(StandardMessageCodec.INSTANCE) {
        
    
        override fun create(context: Context, viewId: Int, args: Any?): PlatformView {
        
            val flutterView = FlutterWebView(context, messenger, viewId, args as Map<String, Any>?)
            return flutterView
        }
    }

新建`FlutterWebViewPlugin`，继承自`FlutterPlugin`

class FlutterWebViewPlugin : FlutterPlugin {
        
    
        override fun onAttachedToEngine(binding: FlutterPlugin.FlutterPluginBinding) {
        
            val messenger: BinaryMessenger = binding.binaryMessenger
            binding
                .platformViewRegistry
                .registerViewFactory(
                    "plugins.flutter.test/webview", FlutterWebViewFactory(messenger)
                )
        }
    
        override fun onDetachedFromEngine(binding: FlutterPlugin.FlutterPluginBinding) {
        
    
        }
    
        companion object {
        
            @JvmStatic
            fun registerWith(registrar: PluginRegistry.Registrar) {
        
                registrar
                    .platformViewRegistry()
                    .registerViewFactory(
                        "plugins.flutter.test/webview",
                        FlutterWebViewFactory(registrar.messenger())
                    )
            }
        }
    }

接着，我们需要注册这个`FlutterWebViewPlugin`  
我们这里使用的是`FlutterBoost`框架，所以，直接在`FlutterBoost`初始化的地方进行注册即可

FlutterBoost.instance().setup(this, new FlutterBoostDelegate() {
        
            @Override
            public void pushNativeRoute(FlutterBoostRouteOptions options) {
        
                //...省略代码...
            }
    
            @Override
            public void pushFlutterRoute(FlutterBoostRouteOptions options) {
        
                //...省略代码...
            }
        }, engine -> {
        
        	//进行FlutterWebViewPlugin的注册
            engine.getPlugins().add(new FlutterWebViewPlugin());       
        });

> 如果没有使用`FlutterBoost`，可以在继承自`FlutterActivity`的代理Activity中进行注册，具体可以看我的另一篇博客 [Flutter和Native之间进行通信][Flutter_Native]

#### Flutter端 ####

新建`liu_web_view.dart`，相当于封装一个组件库

class LiuWebView extends StatefulWidget {
        
      final String url;
      final String iOSWebType;
    
      const LiuWebView(
          {
        Key? key,
          required this.url,
          this.iOSWebType = "full"})
          : super(key: key);
    
      @override
      State<StatefulWidget> createState() {
        
        return _LiuWebViewState();
      }
    }
    
    class _LiuWebViewState extends State<LiuWebView> {
        
      late MethodChannel webViewChannel;
    
      @override
      Widget build(BuildContext context) {
        
        if (defaultTargetPlatform == TargetPlatform.android) {
        
          return AndroidView(
              onPlatformViewCreated: (viewId) {
        
                initWebViewChannel(viewId);
              },
              creationParams: {
        'url': widget.url},
              creationParamsCodec: StandardMessageCodec(),
              viewType: 'plugins.flutter.test/webview');
        } /*else if (defaultTargetPlatform == TargetPlatform.iOS) {
          //IOS相关的逻辑我们可以先不去实现
          return UiKitView(
            onPlatformViewCreated: (viewId) {
              initWebViewChannel(viewId);
            },
            viewType: 'plugins.flutter.test/webview',
            layoutDirection: TextDirection.ltr,
            creationParams: <String, dynamic>{
              'url': widget.url,
              'type': widget.iOSWebType
            },
            creationParamsCodec: const StandardMessageCodec(),
          );
        }*/ else {
        
          throw Exception("not impl:" + defaultTargetPlatform.toString());
        }
      }
    }

最后，在需要的页面里进行使用即可

class _MyHomePageState extends State<MyHomePage> {
        
      
      @override
      Widget build(BuildContext context) {
        
        return Scaffold(
            appBar: AppBar(
              title: Text("Test"),
            ),
            body: Container(
              child: LiuWebView(url: "https://www.baidu.com"),
            ));
      }
    }

#### Flutter和原生View进行双向的交互 ####

如果我们需要将原生WebView的加载状态告知给Flutter，应该怎么做呢 ?  
Flutter和原生的通信我们都知道，是使用Channel来进行交互的。同理，这里也是使用Channel，双向交互的话，我们可以选用MethodChannel。

Android端修改`FlutterWebView`

class FlutterWebView(
        val context: Context,
        val messenger: BinaryMessenger,
        val viewId: Int,
        val args: Map<String, Any>?
    ) : PlatformView, MethodChannel.MethodCallHandler {
        
        private var webView: WebView? = null
        private var methodChannel: MethodChannel
    
        init {
        
            Log.i(TAGs.FLUTTER_WEB_VIEW, "onPageStarted viewId:$viewId")
            methodChannel.setMethodCallHandler(this)
        }
    
        override fun getView(): View {
        
            val curAct = App.getApp().curActivity
            webView = WebView(curAct)
    
            webView?.setWebViewClient(object:WebViewClient(){
        
                override fun onPageStarted(
                    webView: com.tencent.smtt.sdk.WebView?,
                    url: String?,
                    favicon: Bitmap?
                ) {
        
                    super.onPageStarted(webView, url, favicon)
                    //告知Flutter，WebView页面加载已经开始
                    methodChannel.invokeMethod("onLoadStart", url)
                }
    
                override fun onPageFinished(webView: com.tencent.smtt.sdk.WebView?, url: String?) {
        
                    super.onPageFinished(webView, url)
                    //告知Flutter，WebView页面加载已经完毕
                    methodChannel.invokeMethod("onLoadStop", url)
                }
            })
    
            if (args != null) {
        
                val url = args["url"] as String
                webView!!.loadUrl(url)
            } else {
        
                throw IllegalArgumentException("args is null.")
            }
            return webView!!
        }
    
        override fun dispose() {
        
            webView?.destroy()
        }
    
        override fun onMethodCall(call: MethodCall, result: MethodChannel.Result) {
        
    		//这里可以通过 Flutter传过来的 call.method 来实现 Flutter 对 原生的调用
    		if(call.method == "xxxxx"){
        
    			//do something
    		}
        }
    }

Flutter端修改`liu_web_view.dart`

class LiuWebView extends StatefulWidget {
        
      final String url;
      final String iOSWebType;
      final LoadCallback? onLoadStart;
      final LoadCallback? onLoadStop;
    
      const LiuWebView(
          {
        Key? key,
          required this.url,
          this.iOSWebType = "full",
          this.onLoadStart,
          this.onLoadStop})
          : super(key: key);
    
      @override
      State<StatefulWidget> createState() {
        
        return _LiuWebViewState();
      }
    }
    
    typedef LoadCallback = void Function(String url);
    
    class _LiuWebViewState extends State<LiuWebView> {
        
      late MethodChannel webViewChannel;
    
      void initWebViewChannel(int viewId) {
        
        webViewChannel = MethodChannel('com.test/webView$viewId');
        webViewChannel.setMethodCallHandler((call) {
        
          return handleCall(call);
        });
      }
    
      Future<dynamic> handleCall(MethodCall call) async {
        
        logDebug(TAGs.WEB_VIEW, "handleCall method:" + call.method);
        if (call.method == "onLoadStart") {
        
          //收到 原生WebView 开始加载的状态
          String url = call.arguments as String;
          widget.onLoadStart?.call(url);
        } else if (call.method == "onLoadStop") {
        
          //收到 原生WebView 结束加载的状态
          String url = call.arguments as String;
          widget.onLoadStop?.call(url);
        }
      }
    
      @override
      Widget build(BuildContext context) {
        
        if (defaultTargetPlatform == TargetPlatform.android) {
        
          return AndroidView(
              onPlatformViewCreated: (viewId) {
        
                initWebViewChannel(viewId);
              },
              creationParams: {
        'url': widget.url},
              creationParamsCodec: StandardMessageCodec(),
              viewType: 'plugins.flutter.test/webview');
        } /*
    	IOS相关的逻辑我们可以先不去实现
    	else if (defaultTargetPlatform == TargetPlatform.iOS) {
          return UiKitView(
            onPlatformViewCreated: (viewId) {
              initWebViewChannel(viewId);
            },
            viewType: 'plugins.flutter.test/webview',
            layoutDirection: TextDirection.ltr,
            creationParams: <String, dynamic>{
              'url': widget.url,
              'type': widget.iOSWebType
            },
            creationParamsCodec: const StandardMessageCodec(),
          );
        }*/ else {
        
          throw Exception("not impl:" + defaultTargetPlatform.toString());
        }
      }
    }

进行使用

class _MyHomePageState extends State<MyHomePage> {
        
    
      @override
      Widget build(BuildContext context) {
        
        return Scaffold(
            appBar: AppBar(
              title: Text(widget.title),
            ),
            body: Container(
                child: LiuWebView(
                    url: "https://www.baidu.com",
                    onLoadStart: (url) {
        
                      showLoading();
                    },
                    onLoadStop: (url) {
        
                      dismissLoading();
                    }
                ))
        );
      }
    }

OK，完工。这样，我们后期如果有更多方法想要让Flutter来调用，或者原生View的状态回调给Flutter，都可以实现了。

[Flutter_Native]: https://blog.csdn.net/EthanCo/article/details/121394295?spm=1001.2014.3001.5501