PS: 图片上传功能在项目中属于很常见的功能，网上也有蛮多图片上传的框架，看的眼花缭乱的。。。最后，本着自己最熟悉的才是最好的原则选择 Flutter Dio,所以项目中用的网络框架也是Flutter Dio ，直接拿来写个简单的demo，也算记录下Flutter踩坑心酸史吧。。。

• 国际惯例（为了省事没做图片大小限制了。。。）

test.gif

废话不多说了，直接上代码，

• 先添加两个依赖：

dio: any
flutter_picker: ^1.0.11

不熟悉dio的小伙伴可以去看看 Dio

• 全部应用代码直接贴出来（dio可自行封装，这里只演示极简版）

import 'dart:io';

import 'package:dio/dio.dart';
import 'package:flutter/material.dart';
import 'package:fluttertoast/fluttertoast.dart';
import 'package:image_picker/image_picker.dart';

class HeadImageUploadPage extends StatefulWidget {
  @override
  _HeadImageUploadPageState createState() => _HeadImageUploadPageState();
}

class _HeadImageUploadPageState extends State<HeadImageUploadPage> {
  File _image;

  Future getImage() async {
    var image = await ImagePicker.pickImage(source: ImageSource.gallery);
    _upLoadImage(image);
    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),
      ),
    );
  }

  _upLoadImage(File image) async {
    String path = image.path;
    var name = path.substring(path.lastIndexOf("/") + 1, path.length);
    var suffix = name.substring(name.lastIndexOf(".") + 1, name.length);
    FormData formData = new FormData.from({
      "userId": "10000024",
      "file": new UploadFileInfo(new File(path), name,
          contentType: ContentType.parse("image/$suffix"))
    });

    Dio dio = new Dio();
    var respone = await dio.post<String>("/upload", data: formData);
    if (respone.statusCode == 200) {
      Fluttertoast.showToast(
          msg: "图片上传成功",
          gravity: ToastGravity.CENTER,
          textColor: Colors.grey);
    }
  }
}