图像选择器无法获取文件 Flutter

Question

下面的颤动代码允许我从图库中选择图像并将其插入可变文件文件中，但是当我运行代码并尝试打印文件值时它始终为空，我该如何解决这个问题？

飞镖代码：

Future getImage() async {
    PickedFile pickedFile = await ImagePicker().getImage(
      source: ImageSource.gallery,
    );
    if (pickedFile != null) {
      print("file picked");
      file = File(pickedFile.path);
    }
    else{
      print("File not picked");
    }

  }

完整类代码：

File file;
class DocumentiImpiantoView extends StatefulWidget {
  const DocumentiImpiantoView(this.imp);
  final Impianto imp;
  @override
  _DocumentiImpiantoViewState createState() => _DocumentiImpiantoViewState();
}

class _DocumentiImpiantoViewState extends State<DocumentiImpiantoView> {
  TextEditingController _searchController = new TextEditingController();
  Timer timer;

  final picker = ImagePicker();

  _DocumentiImpiantoViewState() {
    timer = Timer.periodic(Duration(seconds: 6), (Timer t) => updateui());
    getData();
  }

  Future<bool> getData() async {
    listadocumenti = await Documento.load(widget.imp);
    return true;
  }

  Future getImage() async {
    PickedFile pickedFile = await ImagePicker().getImage(
      source: ImageSource.gallery,
    );
    if (pickedFile != null) {
      print("file picked");
      file = File(pickedFile.path);
    }
    else{
      print("File not picked");
    }

  }

  updateui() async {
    var values = await Documento.load(widget.imp);
    setState(() {
      listadocumenti = values;
    });
  }

  selectfile() async {
    print("Seleziono il file");
    FilePickerResult result = await FilePicker.platform.pickFiles();
    if (result != null) {
      print("Salvataggio file");
       file = File(result.files.single.path);
    } else {
      // User canceled the picker
    }
  }

  @override
  Widget build(BuildContext context) {
    return FutureBuilder<bool>(
      future: getData(),
      builder: (BuildContext context, AsyncSnapshot<bool> snapshot) {
        return !snapshot.hasData
            ? new Container()
            : Scaffold(
                body: getBody(),
              );
      },
    );
  }

  //Funzione che apre la visualizzazione del file con link
  openfile() {
    //await launch(URL, forceSafariVC: false);
  }

  goback(BuildContext context) {
    final gr = new DettagliImpiantoView(widget.imp);
    Navigator.pushReplacement(context, MaterialPageRoute(builder: (context) => gr));
  }

  //Upload file su impianto
  uploadfile() async {
    print("caricamento file");
    if(file==null){
      print("File è null");
    }
    else {
      try {
        //List<int> fileInByte = file.readAsBytesSync();
        final bytes = File(file.path).readAsBytesSync();
        String base64Image = "data:image/png;base64," + base64Encode(bytes);
        print("caricamento file 2");
        Impianto.uploadfile(widget.imp, base64Image, file.path);
        updateui();
      } catch (err) {
        print("Errore: " + err);
      }
    }
  }

  Widget getBody() {
    return SafeArea(
        child: ListView(
      padding: EdgeInsets.only(left: 20, right: 20, top: 15),
      children: <Widget>[
        Row(
          mainAxisAlignment: MainAxisAlignment.spaceBetween,
          children: <Widget>[
            GestureDetector(
              onTap: () {
                goback(context);
              },
              child: Icon(Icons.arrow_back),
            ),
            Text(
              "Documenti",
              style: TextStyle(fontSize: 22, fontWeight: FontWeight.bold),
            ),
            Icon(Icons.add)
          ],
        ),
        SizedBox(
          height: 10,
        ),
        SizedBox(
          height: 30,
        ),
        SingleChildScrollView(
          scrollDirection: Axis.horizontal,
          child: Row(
            children: <Widget>[
              Padding(
                padding: EdgeInsets.only(right: 20),
                child: Column(
                  children: <Widget>[
                    GestureDetector(
                      onTap: () {
                        uploadfile();
                      },
                      child: Container(
                        width: 70,
                        height: 70,
                        decoration: BoxDecoration(shape: BoxShape.circle, color: grey),
                        child: Center(
                          child: Icon(
                            LineIcons.plus,
                            size: 33,
                          ),
                        ),
                      ),
                    ),
                    SizedBox(
                      height: 10,
                    ),
                    GestureDetector(
                        onTap: () {
                          uploadfile();
                        },
                        child: SizedBox(
                          width: 75,
                          child: Align(
                              child: Text(
                            'Upload File',
                            overflow: TextOverflow.ellipsis,
                          )),
                        )),
                  ],
                ),
              ),
              Row(
                  children: List.generate(optionsList.length, (index) {
                return Padding(
                  padding: const EdgeInsets.only(right: 20),
                  child: Column(
                    children: <Widget>[
                      GestureDetector(
                        onTap: () {
                          if (optionsList[index]["name"] == "Documenti") {
                            selectfile();
                          } else {
                            getImage();
                          }
                        },
                        child: Container(
                          width: 75,
                          height: 75,
                          child: Stack(
                            children: <Widget>[
                              Container(
                                  decoration: BoxDecoration(
                                      shape: BoxShape.circle, border: Border.all(color: blue_story, width: 3)),
                                  child: Padding(
                                    padding: const EdgeInsets.all(3.0),
                                    child: Container(
                                      width: 90,
                                      height: 90,
                                      child: ClipRRect(
                                        borderRadius: BorderRadius.circular(8.0),
                                        child: Image.asset(optionsList[index]['img'], width: 30, height: 30),
                                      ),
                                    ),
                                  )),
                              Positioned(
                                top: 48,
                                left: 52,
                                child: Container(
                                  width: 20,
                                  height: 20,
                                  decoration: BoxDecoration(
                                      color: online,
                                      shape: BoxShape.circle,
                                      border: Border.all(color: white, width: 3)),
                                ),
                              ),
                            ],
                          ),
                        ),
                      ),
                      SizedBox(
                        height: 10,
                      ),
                      SizedBox(
                        width: 90,
                        child: Align(
                            child: Text(
                          optionsList[index]['name'],
                          overflow: TextOverflow.ellipsis,
                        )),
                      )
                    ],
                  ),
                );
              }))
            ],
          ),
        ),
        SizedBox(
          height: 30,
        ),
        Column(
          children: List.generate(listadocumenti.length, (index) {
            return InkWell(
              onTap: () {},
              child: Padding(
                padding: const EdgeInsets.only(bottom: 20),
                child: Row(
                  children: <Widget>[
                    Container(
                      width: 75,
                      height: 75,
                      child: Stack(
                        children: <Widget>[
                          Container(
                            decoration:
                                BoxDecoration(shape: BoxShape.circle, border: Border.all(color: blue_story, width: 3)),
                            child: Padding(
                              padding: const EdgeInsets.all(3.0),
                              child: Container(
                                width: 90,
                                height: 90,
                                child: ClipRRect(
                                  borderRadius: BorderRadius.circular(8.0),
                                  child: Image.asset("assets/images/rapportini.png"),
                                ),
                              ),
                            ),
                          ),
                          Positioned(
                            top: 48,
                            left: 52,
                            child: Container(
                              width: 20,
                              height: 20,
                              decoration: BoxDecoration(
                                  color: online, shape: BoxShape.circle, border: Border.all(color: white, width: 3)),
                            ),
                          )
                        ],
                      ),
                    ),
                    SizedBox(
                      width: 20,
                    ),
                    Column(
                      crossAxisAlignment: CrossAxisAlignment.start,
                      children: <Widget>[
                        Text(
                          listadocumenti[index].Utente,
                          style: TextStyle(fontSize: 17, fontWeight: FontWeight.w500),
                        ),
                        SizedBox(
                          height: 5,
                        ),
                        SizedBox(
                          width: MediaQuery.of(context).size.width - 135,
                          child: Text(
                            listadocumenti[index].IdDoc.toString(),
                            style: TextStyle(fontSize: 15, color: black.withOpacity(0.8)),
                            overflow: TextOverflow.ellipsis,
                          ),
                        )
                      ],
                    )
                  ],
                ),
              ),
            );
          }),
        )
      ],
    ));
  }
}

Answer 1

在您的代码中有几个问题。首先 imagePicker 将图像选择为 Xfile，但您将其分配为文件。像这样编辑您的 getImage 函数。有时，如果图像尺寸太大，可能会出现问题。在这种情况下，压缩图像可能会对您有所帮助。

File? _imageFile;
Future<void> getImage() async {
 XFile? pickedFile = await ImagePicker().pickImage(source: ImageSource.gallery);
 if (pickedFile != null) {
   File selected = File(pickedFile.path);
  _imageFile = selected;
  compressFile(_imageFile!);
 }
}

压缩文件功能

Future<void> compressFile(File file) async {
 if (file.lengthSync() < 1000000) {
  setState(() {
    _imageFile = file;
  });
} else {
ImageProperties properties =
    await FlutterNativeImage.getImageProperties(file.path);
    File result = await FlutterNativeImage.compressImage(file.path,
    quality: 95,
    targetWidth: 600,
    targetHeight: (properties.height! * 600 / 
    properties.width!).round());
    setState(() {
     _imageFile = result;
   });
 }
NavigationService.getCurrentState()?.pop(_imageFile);
}