flutter - 如何在 Flutter 中获取 Assets 对象的路径？

Question

我在 flutter 中使用多图像选择器，我必须将这些图像加载到一个文件中以在照片 View 中显示它们。

我确定我将 Assets 转换为文件的方法不合适。我无法实现这一点，因为我总是收到找不到文件的异常。

这是我的代码:

import 'package:multi_image_picker/multi_image_picker.dart';
import 'package:flutter/material.dart';
import 'dart:async';
import 'dart:io';
import 'package:flutter_swiper/flutter_swiper.dart';
import 'package:photo_view/photo_view.dart';
import 'package:flutter_absolute_path/flutter_absolute_path.dart';
import 'package:path_provider/path_provider.dart';
import 'package:path_provider_platform_interface/path_provider_platform_interface.dart';
void main() => runApp(AddPost());
class AddPost extends StatefulWidget {
@override
_MyAppState createState() => new _MyAppState();
}

class _MyAppState extends State<AddPost> {
List<Asset> images = List<Asset>();
//File images;
List<File>files=List<File>();
String _error = 'No Error Dectected';
var width;
var height;
@override
void initState() {
super.initState();
 }
void getFileList() async {
for (int i = 0; i < images.length; i++) {
  String filename=images[i].name;
String dir = (await getApplicationDocumentsDirectory()).path;
String path='$dir/$filename';
  var path2 = await FlutterAbsolutePath.getAbsolutePath(path);
  //var path = await images[i].filePath; ( the file path thing is not found)
  print(path2);
  var file = await getImageFileFromAsset(path2);
  print(file);
  files.add(file);
  }
  }

  Future<File> getImageFileFromAsset(String path) async {
  final file = File(path);
  return file;
     }




  Widget buildGridView() {

return new Swiper(
    loop: false,

    itemCount: files==null?0:files.length,
    pagination: new SwiperPagination(
      // margin: new EdgeInsets.all(5.0),
        builder: new DotSwiperPaginationBuilder(
            color: Colors.purple, activeColor: Colors.green)),
    itemBuilder: (BuildContext context, int index) {
      return Container(

          child: PhotoView(
            gaplessPlayback: false,
            backgroundDecoration: BoxDecoration(color: Colors.transparent),
            minScale: PhotoViewComputedScale.contained ,
            maxScale: PhotoViewComputedScale.covered ,
            imageProvider: ,

          ));
    }
);
 }

Future<void> loadAssets() async {
List <Asset>resultList ;
try {

  resultList = await  MultiImagePicker.pickImages(
      maxImages: 6,
      enableCamera: true,
      selectedAssets: images,
      cupertinoOptions: CupertinoOptions(takePhotoIcon: "chat"),
      materialOptions: MaterialOptions(
        actionBarColor: "#abcdef",
        actionBarTitle: "Example App",
        allViewTitle: "All Photos",
        useDetailsView: false,
        selectCircleStrokeColor: "#000000",
      ));

} on Exception catch (e) {
  error = e.toString();
}

// If the widget was removed from the tree while the asynchronous platform
// message was in flight, we want to discard the reply rather than calling
// setState to update our non-existent appearance.
if (!mounted) return;

setState(() {
  images = resultList;
  _error = error;
  getFileList();
});




 }

 @override
 Widget build(BuildContext context) {

return new MaterialApp(
  home: new Scaffold(
    appBar: new AppBar(
      title: const Text('Plugin example app'),
    ),
    body: Column(
      children: <Widget>[
        Center(child: Text('Error: $_error')),
        RaisedButton(
          child: Text("Pick images"),
          onPressed: loadAssets,
        ),
        Expanded(
          child: buildGridView(),
        ),

      ],
    ),
  ),
);
 }
 }

这些是我遇到的错误:

java.io.FileNotFoundException:没有内容提供者:/data/user/0/xperience.flutter_app/app_flutter/Camera

除了:

未处理的异常:MissingPluginException(未在 channel flutter_absolute_path 上找到方法 getAbsolutePath 的实现)

感谢任何帮助。

Answer 1

我通过放置 images[i].identifier 解决了我的问题

 void getFileList() async {
 files.clear();
 for (int i = 0; i < images.length; i++) {
  var path2 = await FlutterAbsolutePath.getAbsolutePath(images[i].identifier);
  //var path = await images[i].filePath;
  print(path2);
  var file = await getImageFileFromAsset(path2);
  print(file);
  files.add(file);
}
}