update readme

README.md

@@ -27,10 +27,112 @@ Build MVVM App for Android and IOS with Flutter。
 - [rxdart](https://github.com/ReactiveX/rxdart)：响应式编程
 - [flutter-provide](https://github.com/google/flutter-provide)：通知ui更新数据
 
+> 思想：M-V-VM各层直接通过rx衔接，配合响应式的思想和rxdart的操作符进行逻辑处理，最后通过provide来更新视图。
+
 ### 截图
 
 ![](screenshot.png)
 
+#### Code
+
+```dart
+//remote
+class GithubService{
+  Observable<dynamic> login()=> get("user");
+}
+//repo
+class GithubRepo {
+  final GithubService _remote;
+
+  GithubRepo(this._remote);
+
+  Observable login(String username, String password) {
+    token = "basic " + base64Encode(utf8.encode('$username:$password'));
+    return _remote.login();
+  }
+}
+//viewmodel
+class HomeViewModel extends ChangeNotifier {
+  final GithubRepo _repo; //数据仓库
+  String username = ""; //账号
+  String password = ""; //密码
+  bool _loading = false; // 加载中
+  String _response = ""; //响应数据
+  //...
+  HomeViewModel(this._repo);
+
+  /**
+   * 调用model层的方法进行登录
+   * doOnData : 请求成功时，处理响应数据
+   * doOnError : 请求失败时，处理错误
+   * doOnListen ： 开始时loading为true,通知ui更新
+   * doOnDone ： 结束时loading为false,通知ui更新
+   */
+  Observable login() => _repo
+      .login(username, password)
+      .doOnData((r) => response = r.toString())
+      .doOnError((e, stacktrace) {
+        if (e is DioError) {
+          response = e.response.data.toString();
+        }
+      })
+      .doOnListen(() => loading = true)
+      .doOnDone(() => loading = false);
+}
+
+//view
+class HomeWidget extends StatefulWidget {
+  @override
+  State<StatefulWidget> createState() {
+    return _HomeState(provideHomeViewModel());
+  }
+}
+class _HomeState extends State<HomeWidget>{
+   //...
+  _HomeState(this._viewModel) {
+    providers.provideValue(_viewModel);
+  }
+	
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+        appbar://...,
+        body://...
+       
+        CupertinoButton(
+            onPressed: _login,
+            //...
+         ),
+         Container(
+                //...
+                child: Provide<HomeViewModel>(
+                  builder: (BuildContext context, Widget child,
+                          HomeViewModel value) =>
+                      Text(value.response),
+                ),
+              ),
+        //...
+        
+        );
+  }
+  
+    
+  _login()=>_viewModel.login().doOnListen(() {
+      _controller.forward();
+    }).doOnDone(() {
+      _controller.reverse();
+    }).listen((_) {
+      //success
+      Toast.show("login success",context,type: Toast.SUCCESS);
+    }, onError: (e) {
+      //error
+      dispatchFailure(context, e);
+    });
+ 
+}
+
+```
+
 #### LICENSE
 
 the Apache License