如何上传图片到Flutter服务器？

Question

我想上传一张图片，我正在使用http。客户端（）用于发出请求，

static uploadImage(String id, File file) {
  var httpClient = createHttpClient();

  Map<String, String> headers = new Map<String, String>();
  headers.putIfAbsent("Authorization", () => "---");
  headers.putIfAbsent("Content-Type", () => "application/json");

  var body=new List();
  body.add(id.)
  httpClient.post(URL_UPLOADIMAGE,headers: headers,body: ,encoding: )
}

请求的主体和编码部分应该是什么？

Answer 1

在submitForm（）方法中签出主体。

File _image;

Future cameraImage() async {
  var image = await ImagePicker.pickImage(
    source: ImageSource.camera,
    maxHeight: 240.0,
    maxWidth: 240.0,
  );

  setState(() {
    _image = image;
  });
}

submitForm() async {
  final response = await http.post(
    uri,
    headers: {
      AuthUtils.AUTH_HEADER: _authToken
    },
    body: {
      'user_id': userId
      'photo': _image != null ? 'data:image/png;base64,' +
          base64Encode(_image.readAsBytesSync()) : '',
    },
  );

  final responseJson = json.decode(response.body);

  print(responseJson);
}

Answer 2

最简单的方法是使用http库，

import 'dart:io';
import 'package:http/http.dart' as http;

_asyncFileUpload(String text, File file) async{
   //create multipart request for POST or PATCH method
   var request = http.MultipartRequest("POST", Uri.parse("<url>"));
   //add text fields
   request.fields["text_field"] = text;
   //create multipart using filepath, string or bytes
   var pic = await http.MultipartFile.fromPath("file_field", file.path);
   //add multipart to request
   request.files.add(pic);
   var response = await request.send();

   //Get the response from the server
   var responseData = await response.stream.toBytes();
   var responseString = String.fromCharCodes(responseData);
   print(responseString);
}

Answer 3

使用MultipartRequest类

Upload(File imageFile) async {    
    var stream = new http.ByteStream(DelegatingStream.typed(imageFile.openRead()));
      var length = await imageFile.length();

      var uri = Uri.parse(uploadURL);

     var request = new http.MultipartRequest("POST", uri);
      var multipartFile = new http.MultipartFile('file', stream, length,
          filename: basename(imageFile.path));
          //contentType: new MediaType('image', 'png'));

      request.files.add(multipartFile);
      var response = await request.send();
      print(response.statusCode);
      response.stream.transform(utf8.decoder).listen((value) {
        print(value);
      });
    }

名称空间：

import 'package:path/path.dart';
import 'package:async/async.dart';
import 'dart:io';
import 'package:http/http.dart' as http;