在 整合dio后 我们就需要加载数据，加载完数据后就要绑定到listview上去,listview的数据 是异步加载

Future<ListView> loadData() async{
    var url="";
    Future<dynamic> future=await HttpHelper.post(url);
    future.then((value) {
      print("then======>"+value.toString());
      Map<String, dynamic> result = json.decode(value);
      list=result["result"];
    }
    ).whenComplete((){
      print("==============>complete");
    });
    return ListView.builder(
      itemCount: list.length,
      itemBuilder: (context,index){   
        return new ListTile(
          title: new Text("${list[index]['categoryType']}"),  
        );
      },
    );
    print("aaa");
  }

第二步就是将listview控件赋到build上面

FutureBuilder(future: loadData(), builder: (BuildContext context, AsyncSnapshot<ListView> snapshot) { 
            return Text("aa");
          },)