问题
I tried to find how to select and upload multiple images in flutter but most of the plugins are not working or I did not understand them well. I found little application but it selects and upload only one picture. How to change this code that user can select and upload multiple pictures or is there any other alternatives. Please write in details, i am freshman in coding. Thanks in advance.
import 'package:flutter/material.dart';
import 'dart:io';
import 'package:http/http.dart' as http;
import 'package:image_picker/image_picker.dart';
import 'package:mime/mime.dart';
import 'dart:convert';
import 'package:http_parser/http_parser.dart';
import 'package:toast/toast.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
// This widget is the root of your application.
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Image Upload Demo',
theme: ThemeData(primarySwatch: Colors.pink),
home: ImageInput());
}
}
class ImageInput extends StatefulWidget {
@override
State<StatefulWidget> createState() {
return _ImageInput();
}
}
class _ImageInput extends State<ImageInput> {
// To store the file provided by the image_picker
File _imageFile;
// To track the file uploading state
bool _isUploading = false;
String baseUrl = 'http://YOUR_IPV4_ADDRESS/flutterdemoapi/api.php';
void _getImage(BuildContext context, ImageSource source) async {
File image = await ImagePicker.pickImage(source: source);
setState(() {
_imageFile = image;
});
// Closes the bottom sheet
Navigator.pop(context);
}
Future<Map<String, dynamic>> _uploadImage(File image) async {
setState(() {
_isUploading = true;
});
// Find the mime type of the selected file by looking at the header bytes of the file
final mimeTypeData =
lookupMimeType(image.path, headerBytes: [0xFF, 0xD8]).split('/');
// Intilize the multipart request
final imageUploadRequest =
http.MultipartRequest('POST', Uri.parse(baseUrl));
// Attach the file in the request
final file = await http.MultipartFile.fromPath('image', image.path,
contentType: MediaType(mimeTypeData[0], mimeTypeData[1]));
// Explicitly pass the extension of the image with request body
// Since image_picker has some bugs due which it mixes up
// image extension with file name like this filenamejpge
// Which creates some problem at the server side to manage
// or verify the file extension
imageUploadRequest.fields['ext'] = mimeTypeData[1];
imageUploadRequest.files.add(file);
try {
final streamedResponse = await imageUploadRequest.send();
final response = await http.Response.fromStream(streamedResponse);
if (response.statusCode != 200) {
return null;
}
final Map<String, dynamic> responseData = json.decode(response.body);
_resetState();
return responseData;
} catch (e) {
print(e);
return null;
}
}
void _startUploading() async {
final Map<String, dynamic> response = await _uploadImage(_imageFile);
print(response);
// Check if any error occured
if (response == null || response.containsKey("error")) {
Toast.show("Image Upload Failed!!!", context,
duration: Toast.LENGTH_LONG, gravity: Toast.BOTTOM);
} else {
Toast.show("Image Uploaded Successfully!!!", context,
duration: Toast.LENGTH_LONG, gravity: Toast.BOTTOM);
}
}
void _resetState() {
setState(() {
_isUploading = false;
_imageFile = null;
});
}
void _openImagePickerModal(BuildContext context) {
final flatButtonColor = Theme.of(context).primaryColor;
print('Image Picker Modal Called');
showModalBottomSheet(
context: context,
builder: (BuildContext context) {
return Container(
height: 150.0,
padding: EdgeInsets.all(10.0),
child: Column(
children: <Widget>[
Text(
'Pick an image',
style: TextStyle(fontWeight: FontWeight.bold),
),
SizedBox(
height: 10.0,
),
FlatButton(
textColor: flatButtonColor,
child: Text('Use Camera'),
onPressed: () {
_getImage(context, ImageSource.camera);
},
),
FlatButton(
textColor: flatButtonColor,
child: Text('Use Gallery'),
onPressed: () {
_getImage(context, ImageSource.gallery);
},
),
],
),
);
});
}
Widget _buildUploadBtn() {
Widget btnWidget = Container();
if (_isUploading) {
// File is being uploaded then show a progress indicator
btnWidget = Container(
margin: EdgeInsets.only(top: 10.0),
child: CircularProgressIndicator());
} else if (!_isUploading && _imageFile != null) {
// If image is picked by the user then show a upload btn
btnWidget = Container(
margin: EdgeInsets.only(top: 10.0),
child: RaisedButton(
child: Text('Upload'),
onPressed: () {
_startUploading();
},
color: Colors.pinkAccent,
textColor: Colors.white,
),
);
}
return btnWidget;
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('Image Upload Demo'),
),
body: Column(
children: <Widget>[
Padding(
padding: const EdgeInsets.only(top: 40.0, left: 10.0, right: 10.0),
child: OutlineButton(
onPressed: () => _openImagePickerModal(context),
borderSide:
BorderSide(color: Theme.of(context).accentColor, width: 1.0),
child: Row(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Icon(Icons.camera_alt),
SizedBox(
width: 5.0,
),
Text('Add Image'),
],
),
),
),
_imageFile == null
? Text('Please pick an image')
: Image.file(
_imageFile,
fit: BoxFit.cover,
height: 300.0,
alignment: Alignment.topCenter,
width: MediaQuery.of(context).size.width,
),
_buildUploadBtn(),
],
),
);
}
}
回答1:
I used that package:
dependencies: multi_image_picker: ^4.6.7
Ex:
import 'package:flutter/material.dart';
import 'dart:async';
import 'package:multi_image_picker/multi_image_picker.dart';
void main() => runApp(new MyApp());
class MyApp extends StatefulWidget {
@override
_MyAppState createState() => new _MyAppState();
}
class _MyAppState extends State<MyApp> {
List<Asset> images = List<Asset>();
String _error;
@override
void initState() {
super.initState();
}
Widget buildGridView() {
if (images != null)
return GridView.count(
crossAxisCount: 3,
children: List.generate(images.length, (index) {
Asset asset = images[index];
return AssetThumb(
asset: asset,
width: 300,
height: 300,
);
}),
);
else
return Container(color: Colors.white);
}
Future<void> loadAssets() async {
setState(() {
images = List<Asset>();
});
List<Asset> resultList;
String error;
try {
resultList = await MultiImagePicker.pickImages(
maxImages: 300,
);
} 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;
if (error == null) _error = 'No Error Dectected';
});
}
@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(),
)
],
),
),
);
}
}
来源：https://stackoverflow.com/questions/59802635/how-can-i-select-and-upload-multiple-images-in-flutter