Flutter-小部件更改后小部件消失

Question

我有这个代码。在图像列表页面中，它获取图像并显示它们。当我单击图像时，它会以英雄动画导航到其详细信息页面。但是，当我返回（弹出）图像列表页面时，无法再看到任何图像。它只是空白。

当我返回图像列表页面时，图像不再存在。

class MediaList extends StatefulWidget {
  final tag;

 MediaList(this.tag);

 @override
 State<StatefulWidget> createState() {
    return _MediaListState(this.tag);
  }
}

class _MediaListState extends State<MediaList> with AutomaticKeepAliveClientMixin {
    final tag;
    final GlobalKey<RefreshIndicatorState> _refreshIndicatorKey = new GlobalKey<RefreshIndicatorState>();

    _MediaListState(this.tag);

    Future future;

    List list = new List();


    initState() {
        super.initState();
        future = MediaAPI().pictures(tag);
    }

    Future<void> _refresh() {
        future = MediaAPI().pictures(tag);
        setState((){});
        return future;
    }

    setData(data) {
        for(var i = 0 ; i < data.length; i++) {
            list.add(AnimatingImage(data[i]["image"]));
        }
    }


    @override
    Widget build(BuildContext context) {
        return list.length > 0 
            ?
            RefreshIndicator(
                key: _refreshIndicatorKey,
                onRefresh: _refresh,
                    child: StaggeredGridView.countBuilder(
                    itemCount: list.length,
                    crossAxisCount: 4,
                    itemBuilder: (context, index) {
                        return list[index];
                    },
                    staggeredTileBuilder: (int index) =>
                    new StaggeredTile.fit(2),
                    mainAxisSpacing: 4.0,
                    crossAxisSpacing: 4.0,
                )
            )

            :
        FutureBuilder(
        builder: (context, projectSnap) {
          if (projectSnap.connectionState != ConnectionState.done) {
            //print('project snapshot data is: ${projectSnap.data}');
            print("yp");
            return Container();
          }

          setData(json.decode(projectSnap.data.body));
          return  RefreshIndicator(
            key: _refreshIndicatorKey,
            onRefresh: _refresh,
            child: StaggeredGridView.countBuilder(
                itemCount: json.decode(projectSnap.data.body).length,
                crossAxisCount: 4,
                itemBuilder: (context, index) {
                    return AnimatingImage(json.decode(projectSnap.data.body)[index]["image"]);
                },
                staggeredTileBuilder: (int index) =>
                new StaggeredTile.fit(2),
                mainAxisSpacing: 4.0,
                crossAxisSpacing: 4.0,
            )
          );
        },
        future: future,
      );
    }

    @override
    bool get wantKeepAlive => true;
}



class AnimatingImage extends StatefulWidget  {
    final String url;
    const AnimatingImage(this.url);

  @override
  AnimatingImageState createState() {
    return new AnimatingImageState(this.url);
  }
}

class AnimatingImageState extends State<AnimatingImage>
    with SingleTickerProviderStateMixin {
  CurvedAnimation _animation;
  AnimationController _animationController;
  final url;
  NetworkImage _image;
  AnimatingImageState(this.url);


  bool _loading = true;


  @override
  void initState() {
    _animationController = AnimationController(
    vsync: this,
    duration: Duration(milliseconds: 350),
    )..addListener(() => setState(() {}));
    _animation = CurvedAnimation(
      parent: _animationController,
      curve: Curves.bounceInOut,
    );

    _image = new NetworkImage(
    'https://xxx.xxxxx.com/xyz:)/' + url
  );
     _image.resolve(ImageConfiguration()).addListener(
    ImageStreamListener(
      (info, call) {
        if (this.mounted){
            setState(() { _loading=false; });
            _animationController.forward();
        }
      },
    ),
  );
    super.initState();
  }



  @override
  Widget build(BuildContext context) {
    return 
  Container(
        child:  new Material( 
                    child: new InkWell( 
                        child: new Center( 
                            child:  _loading 
                            ? 
                            new Container(
                                width: double.infinity, 
                                height: ((new Random().nextInt(5) + 1) * 80).toDouble(), 
                                color: Colors.grey[100], 
                                child: 
                                    Center(
                                        child: null)
                                    ) 
                            :
                            new Hero(
                                tag:url, 
                                child:
                            new GestureDetector(
                                onTap: () {
                                    Navigator.push(context, MaterialPageRoute(builder: (context) => MediaDetail(url)));
                                },
                                child:
                                new Container(
                            child: new ScaleTransition(
                                scale: _animation,
                                child:  Image( image: _image))
                            ),),
                        ), 
                    )
                ),
            ),
        );
    }

      @override
  void dispose() {
    _animationController.dispose();
    super.dispose();
  }

}

这是图像细节

class MediaDetail extends StatelessWidget {
  final image;

 MediaDetail(this.image);

 @override
    Widget build(BuildContext context) {
return new Scaffold(
        body: Center(
          child: Container(
            child: Hero(
              tag: image,
              child: Image( image: new NetworkImage(
                        'https://xxx.xxxxxxx.com/xyz:)/' + image
                        )
            ),
          ),
        ),
          ),
      );
    }
}