add the FutureBuilder widget

Author: nb312

lib/const/page_item_const.dart

@@ -272,5 +272,9 @@ const PAGE_ITEMS = [
     "img": PageImage.FLUTTER_OPEN,
     "click": PageName.INTER_POINTER,
   },
-
+  {
+    "title": PageName.ASYNC_FUTURE,
+    "img": PageImage.FLUTTER_OPEN,
+    "click": PageName.ASYNC_FUTURE,
+  },
 ];

lib/const/page_name_const.dart

@@ -60,4 +60,5 @@ class PageName {
   static const INTER_DISMISSIBLE = "Dismissible";
   static const INTER_POINTER = "AbsorbPointer";
   static const INTER_SCROLLABLE = "Scrollable";
+  static const ASYNC_FUTURE = "FutureBuilder";
 }

lib/main.dart

@@ -73,6 +73,7 @@ class FlutterOpenApp extends StatelessWidget {
         PageName.INTER_GESTURE: (context) => GesturePage(),
         PageName.INTER_DISMISSIBLE: (context) => DismissiblePage(),
         PageName.INTER_POINTER: (context) => PointerPage(),
+        PageName.ASYNC_FUTURE: (context) => FuturePage(),
       },
     );
   }

lib/page/_page.dart

@@ -37,3 +37,4 @@ export 'muti/_muti.dart';
 export 'assets/_assets.dart';
 export 'anim/_anim.dart';
 export 'interation/_interaction.dart';
+export 'async/_async.dart';

lib/page/async/FuturePage.dart

@@ -0,0 +1,46 @@
+///
+/// Created by NieBin on 2019/6/13
+/// Github: https://github.com/nb312
+/// Email: niebin312@gmail.com
+
+import "package:flutter/material.dart";
+import "package:flutter_widgets/const/_const.dart";
+
+class FuturePage extends StatefulWidget {
+  @override
+  _FutureState createState() => _FutureState();
+}
+
+class _FutureState extends State<FuturePage> {
+  Future<String> _getData() async {
+    return "Hello world";
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(
+        title: Text("Hello world"),
+      ),
+      body: Container(
+        child: FutureBuilder<String>(
+          future: _getData(), // a previously-obtained Future<String> or null
+          builder: (BuildContext context, AsyncSnapshot<String> snapshot) {
+            switch (snapshot.connectionState) {
+              case ConnectionState.none:
+                return Text('Press button to start.');
+              case ConnectionState.active:
+              case ConnectionState.waiting:
+                return Text('Awaiting result...');
+              case ConnectionState.done:
+                if (snapshot.hasError) return Text('Error: ${snapshot.error}');
+                return Text('Result: ${snapshot.data}');
+            }
+            return RefreshIndicator(
+                child: null, onRefresh: null); // unreachable
+          },
+        ),
+      ),
+    );
+  }
+}

lib/page/async/_async.dart

@@ -0,0 +1,6 @@
+///
+/// Created by NieBin on 2019/6/13
+/// Github: https://github.com/nb312
+/// Email: niebin312@gmail.com
+///
+export "FuturePage.dart";