Add:创建 flutter go web 版

lib/widgets/components/Scroll/BoxScrollView/demo.dart

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+/// @Author: 一凨 
+/// @Date: 2018-12-17 13:16:29 
+/// @Last Modified by: 一凨
+/// @Last Modified time: 2018-12-17 13:43:01
+
+import 'package:flutter_web/material.dart';
+//import 'package:flutter/rendering.dart';
+
+class BoxScrollViewDemo extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    return Center(
+      child: Column(
+        children: <Widget>[
+          Text('滚动一下就看看吧 s(￣▽￣)~*'),
+          Container(
+            height: 300.0,
+            child: ListViewDemo(
+              children: <Widget>[
+                BoxItem(),
+                BoxItem(),
+                BoxItem(),
+                BoxItem(),
+                BoxItem(),
+                BoxItem(),
+                BoxItem(),
+                BoxItem(),
+                BoxItem(),
+              ],
+            ),
+          )
+        ],
+      ),
+    );
+  }
+}
+
+class BoxItem extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    return Container(
+      height: 60.0,
+      margin: const EdgeInsets.symmetric(vertical: 20.0),
+      color: Theme.of(context).primaryColor,
+      child: Text(
+        '测试继承BoxScrollView',
+        style: TextStyle(color: Colors.white),
+      ),
+    );
+  }
+}
+
+class ListViewDemo extends BoxScrollView {
+  // 构造函数
+  ListViewDemo({
+    Key key,
+    Axis scrollDirection = Axis.vertical,
+    bool reverse = false,
+    ScrollController controller,
+    bool primary,
+    ScrollPhysics physics,
+    bool shrinkWrap = false,
+    EdgeInsetsGeometry padding,
+    this.itemExtent,
+    bool addAutomaticKeepAlives = true,
+    bool addRepaintBoundaries = true,
+    bool addSemanticIndexes = true,
+    double cacheExtent,
+    List<Widget> children = const <Widget>[],
+    int semanticChildCount,
+  })  : childrenDelegate = SliverChildListDelegate(
+          children,
+          addAutomaticKeepAlives: addAutomaticKeepAlives,
+          addRepaintBoundaries: addRepaintBoundaries,
+          addSemanticIndexes: addSemanticIndexes,
+        ),
+        super(
+          key: key,
+          scrollDirection: scrollDirection,
+          reverse: reverse,
+          controller: controller,
+          primary: primary,
+          physics: physics,
+          shrinkWrap: shrinkWrap,
+          padding: padding,
+          cacheExtent: cacheExtent,
+          semanticChildCount: semanticChildCount ?? children.length,
+        );
+
+  final double itemExtent;
+  final SliverChildDelegate childrenDelegate;
+
+// 子类应重写此方法以构建布局模型。
+  @override
+  Widget buildChildLayout(BuildContext context) {
+    if (itemExtent != null) {
+      return SliverFixedExtentList(
+        delegate: childrenDelegate,
+        itemExtent: itemExtent,
+      );
+    }
+    return SliverList(delegate: childrenDelegate);
+  }
+}