view model？

netrain_flutter_app/lib/douwen/Demo2.dart

+import 'package:flutter/material.dart';
+import 'package:flutter/src/widgets/framework.dart';
+import 'package:flutter/widgets.dart';
+import 'package:netrain_flutter_app/douwen/custom/BaseView.dart';
+import 'package:netrain_flutter_app/douwen/custom/BaseViewModel.dart';
+
+class Demo2 extends BaseView {
+  Demo2() : super(BaseViewModel()) {
+    builder = (context, value, child) => Container(
+            child: Column(
+          children: [
+            Row(
+              children: [
+                _item("setNormal", () {
+                  viewModel.setNormal();
+                }),
+                _item("setEmpty", () {
+                  viewModel.setEmpty();
+                }),
+                _item("setError", () {
+                  viewModel.setError();
+                }),
+              ],
+            ),
+            setReplaceView(Row(
+              children: [
+                ValueListenableBuilder(
+                    valueListenable: viewModel.num,
+                    builder: (context, value, child) =>
+                        Text("点击了${viewModel.num.value}次")),
+                ElevatedButton(
+                    onPressed: () {
+                      viewModel.click();
+                    },
+                    child: Text("点击"))
+              ],
+            )),
+          ],
+        ));
+  }
+
+  _item(String title, VoidCallback onPressed) {
+    return Container(
+      child: RaisedButton(
+        onPressed: onPressed,
+        child: Text(title),
+      ),
+    );
+  }
+}

netrain_flutter_app/lib/douwen/custom/BaseView.dart

+import 'package:flutter/widgets.dart';
+import 'package:netrain_flutter_app/douwen/custom/BaseViewModel.dart';
+import 'package:provider/provider.dart';
+
+import 'EmptyPage.dart';
+import 'ErrorPage.dart';
+import 'ViewState.dart';
+
+class BaseView extends StatefulWidget {
+  BaseViewModel viewModel;
+  Widget Function(BuildContext context, BaseViewModel value, Widget child)
+      builder;
+  Widget _mReplaceView;
+  Widget emptyView = EmptyPage();
+  Widget errorView = ErrorPage();
+
+  BaseView(this.viewModel) {
+  }
+
+
+  Widget setReplaceView(Widget replaceView) {
+    _mReplaceView = replaceView;
+    switch (viewModel.viewState ?? ViewState.Normal) {
+      case ViewState.Normal:
+        return _mReplaceView;
+      case ViewState.Empty:
+        return emptyView;
+      case ViewState.Error:
+        return errorView;
+      case ViewState.Loading:
+        return _mReplaceView;
+      default:
+        return _mReplaceView;
+    }
+  }
+
+  @override
+  State<StatefulWidget> createState() {
+    return _BaseViewState();
+  }
+}
+
+class _BaseViewState extends State<BaseView> {
+  BaseViewModel viewModel;
+
+  @override
+  void initState() {
+    viewModel = widget.viewModel;
+    super.initState();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return ChangeNotifierProvider(
+      create: (content) => viewModel,
+      child: Consumer<BaseViewModel>(
+        builder: widget.builder,
+      ),
+    );
+  }
+}

netrain_flutter_app/lib/douwen/custom/BaseViewModel.dart

+import 'package:flutter/widgets.dart';
+
+import 'ViewState.dart';
+
+class BaseViewModel with ChangeNotifier {
+  var _viewState;
+  var num = ValueNotifier<int>(0);
+
+  set viewState(ViewState viewState) => setViewState(viewState);
+  get viewState => _viewState;
+
+  void click() {
+    num.value = (num.value ?? 0) + 1;
+    num.notifyListeners();
+  }
+
+  void setNormal() {
+    viewState = ViewState.Normal;
+  }
+
+  void setEmpty() {
+    viewState = ViewState.Empty;
+  }
+
+  void setLoading() {
+    viewState = ViewState.Loading;
+  }
+
+  void setError() {
+    viewState = ViewState.Error;
+  }
+
+  setViewState(ViewState viewState) {
+    if (_viewState == viewState) {
+      return;
+    }
+    _viewState = viewState;
+    notifyListeners();
+  }
+}

netrain_flutter_app/lib/douwen/custom/EmptyPage.dart

+import 'package:flutter/widgets.dart';
+
+class EmptyPage extends Container{
+
+  @override
+  Widget build(BuildContext context) {
+    return Center(
+      child: Container(
+        child: Text("This is EmptyView"),
+      ),
+    );
+  }
+}
\ No newline at end of file

netrain_flutter_app/lib/douwen/custom/ErrorPage.dart

+import 'package:flutter/widgets.dart';
+
+class ErrorPage extends Container{
+
+  @override
+  Widget build(BuildContext context) {
+    return Center(
+      child: Container(
+        child: Text("This is ErrorView"),
+      ),
+    );
+  }
+}
\ No newline at end of file

netrain_flutter_app/lib/douwen/custom/ViewState.dart

+enum ViewState { Normal, Empty, Error, Loading }

netrain_flutter_app/lib/douwen/dwMain.dart

 import 'package:flutter/material.dart';
 import 'package:fluttertoast/fluttertoast.dart';
 import 'package:netrain_flutter_app/common/Images.dart';
+import 'package:netrain_flutter_app/douwen/custom/BaseView.dart';
+import 'package:netrain_flutter_app/douwen/custom/BaseViewModel.dart';
 
+import 'Demo2.dart';
 import 'secondpage.dart';
 
 void main() {
@@ -14,6 +17,8 @@ void main() {
 
 class MyApp extends StatelessWidget {
   // This widget is the root of your application.
+  BaseViewModel viewModel = BaseViewModel();
+
   @override
   Widget build(BuildContext context) {
     return WillPopScope(
@@ -26,12 +31,14 @@ class MyApp extends StatelessWidget {
           ),
           initialRoute: "key1",
           routes: <String, WidgetBuilder>{
-            "key1": (context) => Scaffold(
-              appBar: AppBar(
-                title: Text("路由"),
-              ),
-              body: RouterNavigator(title: 'Flutter Demo Home Page'),
-            ),
+            "key1": (context) =>
+                Scaffold(
+                    body: Scaffold(
+                      appBar: AppBar(
+                        title: Text("这个是标题"),
+                      ),
+                      body:Demo2(),
+                    )),
             "key2": (context) => Second()
           },
         ),
@@ -40,33 +47,6 @@ class MyApp extends StatelessWidget {
           return true;
         });
   }
-}
-
-class RouterNavigator extends StatefulWidget {
-  RouterNavigator({Key key, this.title}) : super(key: key);
-  final String title;
-
-  @override
-  _RouterNavigatorState createState() => _RouterNavigatorState();
-}
-
-class _RouterNavigatorState extends State<RouterNavigator> {
-  bool byName = false;
-
-  @override
-  Widget build(BuildContext context) {
-    return Container(
-      child: Column(
-        children: [
-          _item("跳转", () async {
-            var result = await Navigator.push(context, MaterialPageRoute(builder: (context) => Second()));
-            print("返回值：$result");
-          }),
-          Image.asset(Images.bg_my_01)
-        ],
-      ),
-    );
-  }
 
   _item(String title, VoidCallback onPressed) {
     return Container(

netrain_flutter_app/pubspec.yaml

@@ -43,6 +43,7 @@ dependencies:
   convert: ^3.0.1 #转码器
   pull_to_refresh: ^2.0.0
   shared_preferences: ^2.0.6
+  provider: ^4.1.0
 
 
 dev_dependencies: