flutter-image-upload-aws-s3-driver.dart

import 'package:flutter/material.dart';
import 'package:path/path.dart';
import 'package:image_picker/image_picker.dart';
import 'dart:io';
import 'dart:async';
import 'package:dio/dio.dart';


/**
 * accepts two parameters,the endpoint and the file
 * returns Response from server
 */
Future<Response> sendFile(String url, File file) async {
  Dio dio = new Dio();
  var len = await file.length();
  var response = await dio.put(url,
      data: file.openRead(),
      options: Options(headers: {
        Headers.contentLengthHeader: len,
      } // set content-length
          ));
  return response;
}

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);
  final String title;
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  File _image;

  Future getImage() async {
    var image = await ImagePicker.pickImage(source: ImageSource.camera);

    print('upload started');
    var url = 'aws-s3'
    var res2 =
        await sendFile(url, image);
    print("res-2 $res2");
    setState(() {
      _image = image;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Image Picker Example'),
      ),
      body: Center(
        child: _image == null ? Text('No image selected.') : Image.file(_image),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: getImage,
        tooltip: 'Pick Image',
        child: Icon(Icons.add_a_photo),
      ),
    );
  }
}