1、增加JS互调方法showToast；

lib/widget/complaint_web_view.dart

@@ -76,7 +76,13 @@ class _ComplaintWebPageState extends State<ComplaintWebPage> {
           onMessageReceived: (JavaScriptMessage message) async {
         debugPrint(
             "JavascriptChannel:method = finishPage message = ${message.message}");
-        finishPage(message.message);
+        _finishPage(message.message);
+      })
+      ..addJavaScriptChannel("showToast",
+          onMessageReceived: (JavaScriptMessage message) async {
+        debugPrint(
+            "JavascriptChannel:method = showToast message = ${message.message}");
+        _onShowToast(message.message);
       })
       ..setNavigationDelegate(
           NavigationDelegate(onPageFinished: _onPageFinished))
@@ -161,8 +167,8 @@ class _ComplaintWebPageState extends State<ComplaintWebPage> {
     final jpg = image.encodeJpg(scaledImage, quality: 90);
 
     final filePath = (await getTemporaryDirectory()).uri.resolve(
-      './image_${DateTime.now().microsecondsSinceEpoch}.jpg',
-    );
+          './image_${DateTime.now().microsecondsSinceEpoch}.jpg',
+        );
     final file = await File.fromUri(filePath).create(recursive: true);
     await file.writeAsBytes(jpg, flush: true);
     debugPrint("file = ${file.uri.toString()}");
@@ -188,8 +194,13 @@ class _ComplaintWebPageState extends State<ComplaintWebPage> {
   }
 
   /// 关闭页面
-  finishPage(String? msg) {
+  _finishPage(String? msg) {
     debugPrint("finishPage：");
     Navigator.pop(context);
   }
+
+  /// 展示toast
+  _onShowToast(String? msg) {
+    ToastUtil.showToast(msg);
+  }
 }