如何在 flutter 中不使用 image_picker 或其他包的情况下从图库中获取图像

您可以查看后台的工作原理，并检查其本机实现以确定可以使用的本机方法。image_picker

https://github.com/flutter/packages/tree/main/packages/image_picker/image_picker_android/android/src/main/java/io/flutter/plugins/imagepicker

请参阅此页面，了解如何在 Flutter 应用中运行原生代码（您也可以在不使用包的情况下运行）： https://docs.flutter.dev/platform-integration/platform-channels

问题是，为什么你不能使用包？如果前者不起作用，它们应该很容易通过 pub.dev 甚至作为本地依赖项包含在您的中。pubspec.yaml

为了显示预览，我知道将文件复制到应用程序的临时目录（您可以与 path_provider一起使用），之后您可以在应用程序中显示为预览。image_pickergetTemporaryDirectory()Image.file

是的，你可以做到。查看下面的代码段。

1.首先，您应该将可变 As 类型设为类型。File

File? _imageFile;

2.然后你应该做一个选择图像的方法，就像下面一样，

  Future<void> _selectImageFromGallery() async {
    final picker = ImagePicker();
    final pickedImage = await picker.pickImage(source: ImageSource.gallery);

    if (pickedImage != null) {
      setState(() {
        _imageFile = File(pickedImage.path);
      });
    }
  }

3.现在您可以访问以下代码等图像。

  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Select Image from Gallery'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            _imageFile != null
                ? Image.file(
                    _imageFile!,
                    width: 200,
                    height: 200,
                  )
                : Text('No image selected'),
            SizedBox(height: 20),
            ElevatedButton(
              onPressed: _selectImageFromGallery,
              child: Text('Select Image'),
            ),
          ],
        ),
      ),
    );
  }

完整代码部分

class UploadImage extends StatefulWidget {
  const UploadImage({super.key});

  @override
  State<UploadImage> createState() => _UploadImageState();
}

    class _UploadImageState extends State<UploadImage> {
      
    
      File? _imageFile;
    
      Future<void> _selectImageFromGallery() async {
        final picker = ImagePicker();
        final pickedImage = await picker.pickImage(source: ImageSource.gallery);
    
        if (pickedImage != null) {
          setState(() {
            _imageFile = File(pickedImage.path);
          });
        }
      }
    
      @override
      Widget build(BuildContext context) {
        return Scaffold(
          appBar: AppBar(
            title: Text('Select Image from Gallery'),
          ),
          body: Center(
            child: Column(
              mainAxisAlignment: MainAxisAlignment.center,
              children: <Widget>[
                _imageFile != null
                    ? Image.file(
                        _imageFile!,
                        width: 200,
                        height: 200,
                      )
                    : Text('No image selected'),
                SizedBox(height: 20),
                ElevatedButton(
                  onPressed: _selectImageFromGallery,
                  child: Text('Select Image'),
                ),
              ],
            ),
          ),
        );
    
      }
      }

**如果您想使用 filepicker 尝试以下步骤，

1.在使用此方法之前，您应该添加一些软件包，

  file_picker: ^5.5.0

您可以使用此链接获取它

现在你可以像这样导入它了'package:file_picker/file_picker.dart';

import 'package:file_picker/file_picker.dart';
import 'package:flutter/material.dart';

    class UploadImage extends StatefulWidget {
      const UploadImage({super.key});
    
      @override
      State<UploadImage> createState() => _UploadImageState();
    }
    
    class _UploadImageState extends State<UploadImage> {
      File? file;
    
      @override
      Widget build(BuildContext context) {
        return Scaffold(
          appBar: AppBar(
            title: const Text('Upload Image'),
          ),
          body: SingleChildScrollView(
            child: Center(
              child: Column(
                children: [
                  file != null
                      ? Image.file(file!)
                      : Image.asset('assets/images/defult.png'),
                  TextButton(
                    onPressed: () {
                      pickFile();
                    },
                    child: const Text('Pick a file'),
                  ),
                ],
              ),
            ),
          ),
        );
      }
    
      pickFile() async {
        FilePickerResult? result =
            await FilePicker.platform.pickFiles(type: FileType.image);
    
        if (result != null) {
          setState(() {
            file = File(result.files.single.path ?? "");
          });
        }
      }

尝试这样，您现在可以解决您的问题。

您可以在 MediaStore 中查询图像文件。

如果您拥有READ_MEDIA_IMAGES权限，您将获得设备上的所有文件。