Flutter Dio：如何上传图片？

Question

我正在尝试邮递员。它有效

我想使用 Package DIO Package将一些图像上传到 rest-api ，我是这个包的新手（我将此包仅用于 CRUD 操作），并且在上传图像操作时遇到问题。
我已经在阅读文档，但没有看到上传图片。我正在尝试此代码（参考文档）并遇到一些错误：

error:FileSystemException
message :"Cannot retrieve length of file"
OSError (OS Error: No such file or directory, errno = 2)
"File: '/storage/emulated/0/Android/data/com.example.mosque/files/Pictures/scaled_IMG_20190815_183541.jpg'"
Type (FileSystemException)
message:FileSystemException: Cannot retrieve length of file, path = 'File: '/storage/emulated/0/Android/data/com.example.mosque/files/Pictures/scaled_IMG_20190815_183541.jpg'' (OS Error: No such file or directory, errno = 2)
DioErrorType (DioErrorType.DEFAULT)
name:"DioErrorType.DEFAULT"

飞镖

Future uploadImage({dynamic data,Options options}) async{
      Response apiRespon =  await dio.post('$baseURL/mahasiswa/upload/',data: data,options: options);
      if(apiRespon.statusCode== 201){
        return apiRespon.statusCode==201;
      }else{
        print('errr');
        return null;
      }
}

查看.dart

void uploadImage() async {
    FormData formData = FormData.from({
      "name_image": _txtNameImage.text,
      "image": UploadFileInfo(File("$_image"), "image.jpg")
    });
    bool upload =
        await api.uploadImage(data: formData, options: CrudComponent.options);
    upload ? print('success') : print('fail');
  }

_image是文件类型

我希望这个包的专家可以帮助我处理这个代码并建议我上传图片。
谢谢。

完整的 View.dart 代码

import 'dart:io';

import 'package:dio/dio.dart';
import 'package:flutter/material.dart';
import 'package:image_picker/image_picker.dart';
import 'package:mosque/api/api_mosque.dart';

class UploadImage extends StatefulWidget {
  @override
  _UploadImageState createState() => _UploadImageState();
}

class _UploadImageState extends State<UploadImage> {
  ApiHelper api = ApiHelper();
  File _image;
  TextEditingController _txtNameImage = TextEditingController();
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        leading: IconButton(
          icon: Icon(Icons.arrow_left),
          onPressed: () => Navigator.pop(context, false),
        ),
        actions: <Widget>[
          IconButton(
            icon: Icon(Icons.file_upload),
            onPressed: () {
              uploadImage();
            },
          )
        ],
      ),
      body: _formUpload(),
    );
  }

  Widget _formUpload() {
    return SingleChildScrollView(
      scrollDirection: Axis.vertical,
      child: Column(
        children: <Widget>[
          TextField(
            controller: _txtNameImage,
            keyboardType: TextInputType.text,
            decoration: InputDecoration(hintText: "Nama Image"),
            maxLength: 9,
            textAlign: TextAlign.center,
          ),
          SizedBox(
            height: 50.0,
          ),
          Container(
            child: _image == null
                ? Text('No Images Selected')
                : Image.file(_image),
          ),
          SizedBox(
            height: 50.0,
          ),
          Row(
            mainAxisAlignment: MainAxisAlignment.center,
            children: <Widget>[
              RaisedButton(
                child: Icon(Icons.camera),
                onPressed: () => getImageCamera(),
              ),
              SizedBox(
                width: 50.0,
              ),
              RaisedButton(
                child: Icon(Icons.image),
                onPressed: () => getImageGallery(),
              )
            ],
          )
        ],
      ),
    );
  }

  void uploadImage() async {
    FormData formData = FormData.from({
      "name_image": _txtNameImage.text,
      "image": UploadFileInfo(File("$_image"), "image.jpg")
    });
    bool upload =
        await api.uploadImage(data: formData, options: CrudComponent.options);
    upload ? print('success') : print('fail');
  }

  getImageGallery() async {
    var imageFile = await ImagePicker.pickImage(source: ImageSource.gallery);
    setState(() {
      _image = imageFile;
    });
  }

  getImageCamera() async {
    var imageFile = await ImagePicker.pickImage(source: ImageSource.camera);
    setState(() {
      _image = imageFile;
    });
  }
}

Answer 1

在Dio 最新版本中，UploadFileInfo方法已被MultipartFile类取代。这里是如何使用发布图像、视频或任何文件的方式：

Future<String> uploadImage(File file) async {
    String fileName = file.path.split('/').last;
    FormData formData = FormData.fromMap({
        "file":
            await MultipartFile.fromFile(file.path, filename:fileName),
    });
    response = await dio.post("/info", data: formData);
    return response.data['id'];
}

Answer 2

即使这个问题是在不久前提出的，我相信主要问题是size图像的问题，尤其是Laravel. Flutter Image Picker库提供了一些减小图像大小的功能，我通过以下步骤解决了这个问题：

1. 创建一个获取图像的方法，我正在使用Camera捕获照片

   Future getImage() async {
        File _image;
        final picker = ImagePicker(); 
   
       var _pickedFile = await picker.getImage(
       source: ImageSource.camera,
       imageQuality: 50, // <- Reduce Image quality
       maxHeight: 500,  // <- reduce the image size
       maxWidth: 500);
   
      _image = _pickedFile.path;
   
   
     _upload(_image);
   
   }
   

2. _upload上传照片的创建方法，我使用的是Dio包Dio包

   void _upload(File file) async {
      String fileName = file.path.split('/').last;
   
      FormData data = FormData.fromMap({
         "file": await MultipartFile.fromFile(
           file.path,
           filename: fileName,
         ),
      });
   
     Dio dio = new Dio();
   
     dio.post("http://192.168.43.225/api/media", data: data)
     .then((response) => print(response))
     .catchError((error) => print(error));
   }
   

3. 在服务器端，我使用Laravel Laravel，我处理请求如下

   public function store(Request $request)
   {
       $file = $request->file('file');
   
       $extension = $file->getClientOriginalExtension();
   
       $fullFileName = time(). '.'. $extension;
       $file->storeAs('uploads', $fullFileName,  ['disk' => 'local']);
   
       return 'uploaded Successfully';
   }
   

Answer 3

在最新版本的Dio中：

它应该看起来像这样。

String fileName = imageFile.path.split('/').last;
FormData formData = FormData.fromMap({
  "image-param-name": await MultipartFile.fromFile(
    imageFile.path,
    filename: fileName,
    contentType: new MediaType("image", "jpeg"), //important
  ),
});

如果没有这一行。

contentType: new MediaType("image", "jpeg")

也许会导致错误：DioError [DioErrorType.RESPONSE]: Http status error [400] Exception

并MediaType进入这个包：http_parser

Answer 4

以下代码将多个图像文件从 dio 客户端上传到 golang 服务器。

1. dioclient.dart

 FormData formData = FormData.fromMap({
   "name": "wendux",
   "age": 25,
   "other" : "params",
 });
 for (File item in yourFileList)
   formData.files.addAll([
     MapEntry("image_files", await MultipartFile.fromFile(item.path)),
   ]);
 Dio dio = new Dio()..options.baseUrl = "http://serverURL:port";
 dio.post("/uploadFile", data: formData).then((response) {
   print(response);
 }).catchError((error) => print(error));

2. golang服务器.go

package main
import (
    "fmt"
    "io"
    "net/http"
    "os"
)
func uploadFile(w http.ResponseWriter, r *http.Request) {
    err := r.ParseMultipartForm(200000)
    if err != nil {
        fmt.Fprintln(w, err)
        return
    }
    formdata := r.MultipartForm
    files := formdata.File["image_files"]
    for i, _ := range files {
        file, err := files[i].Open()
        defer file.Close()
        if err != nil {
            fmt.Fprintln(w, err)
            return
        }
        out, err := os.Create("/path/to/dir/" + files[i].Filename)
        defer out.Close()
        if err != nil {
            fmt.Fprintf(w, "Unable to create the file for writing. Check your write access privilege")
            return
        }
        _, err = io.Copy(out, file)
        if err != nil {
            fmt.Fprintln(w, err)
            return
        }
        fmt.Fprintf(w, "Files uploaded successfully : ")
        fmt.Fprintf(w, files[i].Filename+"\n")
    }
}
func startServer() {
    http.HandleFunc("/uploadFile", uploadFile)
    http.ListenAndServe(":9983", nil)
}
func main() {
    fmt.Println("Server starts!")
    startServer()
}