如何正确上传视频文件？

如何解决如何正确上传视频文件？

这是我要实现的目标（粗体和斜体字表示我正在苦苦挣扎的部分）：

最初，有一个带有添加徽标的浮动操作按钮。单击时，用户将需要使用手机摄像头录制一些东西。用户确认上传录制的视频后，如果连接状态尚未完成，则 将会有一个处理环。连接状态完成后，用户将可以在屏幕上看到他们录制的视频 。

main.dart

import 'dart:io';

import 'package:flutter/material.dart';
import 'package:image_picker/image_picker.dart';
import 'package:video_player/video_player.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: VideoPlayerScreen(),);
  }
}

class VideoPlayerScreen extends StatefulWidget {

  @override
  _VideoPlayerScreenState createState() => _VideoPlayerScreenState();
}

class _VideoPlayerScreenState extends State<VideoPlayerScreen> {
  VideoPlayerController _controller;
  Future<void> _initializeVideoPlayerFuture;

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

  void getVideo() async {
    File videoFile = await ImagePicker.pickVideo(source: ImageSource.camera);
    if (videoFile != null) {
      _controller = VideoPlayerController.file(videoFile);
      _initializeVideoPlayerFuture = _controller.initialize();
      print('videoFile is not null.');
    }
    else print('videoFile is null.');
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Butterfly Video'),),body: _controller != null ?
          FutureBuilder(
            future: _initializeVideoPlayerFuture,builder: (context,snapshot) {
              if (snapshot.connectionState == ConnectionState.done) {
                return AspectRatio(
                  aspectRatio: _controller.value.aspectRatio,child: VideoPlayer(_controller),);
              }
              else {
                return Center(child: CircularProgressIndicator());
              }
            }
          ) : Container(child: Text('Hello something.')),floatingActionButton: _controller != null ? FloatingActionButton(
        onPressed: () {
          setState(() {
            if (_controller.value.isPlaying)
              _controller.pause();
            else
              _controller.play();
          });
        },child: Icon(_controller.value.isPlaying ? Icons.pause : Icons.play_arrow),) : FloatingActionButton(
        onPressed: getVideo,child: Icon(Icons.add),)
    );
  }
}

以下是我尝试上传视频后进入控制台的信息（我使用的是真正的android设备）。

Launching lib/main.dart on A37fw in debug mode...
Running Gradle task 'assembleDebug'...
✓ Built build/app/outputs/flutter-apk/app-debug.apk.
Installing build/app/outputs/flutter-apk/app.apk...
Waiting for A37fw to report its views...
Debug service listening on ws://127.0.0.1:56793/lthez2neUf4=/ws
Syncing files to device A37fw...
I/flutter (  372): videoFile is not null.
I/art     (  372): Rejecting re-init on previously-failed class java.lang.Class<com.google.android.exoplayer2.video.MediaCodecVideoRenderer$OnFrameRenderedListenerV23>
I/art     (  372): Rejecting re-init on previously-failed class java.lang.Class<com.google.android.exoplayer2.video.MediaCodecVideoRenderer$OnFrameRenderedListenerV23>
I/art     (  372): Rejecting re-init on previously-failed class java.lang.Class<com.google.android.exoplayer2.video.MediaCodecVideoRenderer$OnFrameRenderedListenerV23>
I/art     (  372): Rejecting re-init on previously-failed class java.lang.Class<com.google.android.exoplayer2.video.MediaCodecVideoRenderer$OnFrameRenderedListenerV23>
I/art     (  372): Rejecting re-init on previously-failed class java.lang.Class<com.google.android.exoplayer2.video.MediaCodecVideoRenderer$OnFrameRenderedListenerV23>
I/ExoPlayerImpl(  372): Init 3bca4e2a [ExoPlayerLib/2.9.6] [A37f,A37fw,OPPO,22]
W/AudioCapabilities(  372): Unsupported mime audio/evrc
W/AudioCapabilities(  372): Unsupported mime audio/qcelp
W/VideoCapabilities(  372): Unrecognized profile 2130706433 for video/avc
W/AudioCapabilities(  372): Unsupported mime audio/qcelp
W/AudioCapabilities(  372): Unsupported mime audio/evrc
W/VideoCapabilities(  372): Unsupported mime video/mpeg2
W/VideoCapabilities(  372): Unsupported mime video/mpeg2
W/VideoCapabilities(  372): Unsupported mime video/x-ms-wmv
W/VideoCapabilities(  372): Unsupported mime video/divx
W/VideoCapabilities(  372): Unsupported mime video/divx311
W/VideoCapabilities(  372): Unsupported mime video/divx4
W/VideoCapabilities(  372): Unsupported mime video/mp4v-esdp
I/VideoCapabilities(  372): Unsupported profile 4 for video/mp4v-es
I/OMXClient(  372): Using client-side OMX mux.
I/ACodec  (  372): [OMX.qcom.video.decoder.avc] DRC Mode: Dynamic Buffer Mode
I/ExtendedCodec(  372): Decoder will be in frame by frame mode
I/ACodec  (  372): onStart [OMX.qcom.video.decoder.avc]
I/OMXClient(  372): Using client-side OMX mux.
I/ACodec  (  372): onStart [OMX.google.aac.decoder]

更新：如果我在setState函数中将_controller添加到_initializeVideoPlayerFuture和getVideo()中，则可以正常工作。但是控制台日志信息和警告仍然存在，该如何解决？