Flutter 颤振-[barcode_scan]ScanResult不是String类型的子类型
我试图用Flutter 颤振-[barcode_scan]ScanResult不是String类型的子类型,flutter,barcode-scanner,Flutter,Barcode Scanner,我试图用条形码\u scan和下面的代码一起使用flatter扫描二维码,但我一直在出错:未知错误类型“ScanResult”不是typecast扫描中“String”类型的子类型 有人能给我一个解释吗?或者有人能有一个想法吗 import 'package:barcode_scan/gen/protos/protos.pbserver.dart'; import 'dart:async'; import 'package:flutter/material.dart';
条形码\u scan
和下面的代码一起使用flatter扫描二维码,但我一直在出错:未知错误类型“ScanResult”不是typecast扫描中“String”类型的子类型
有人能给我一个解释吗?或者有人能有一个想法吗
import 'package:barcode_scan/gen/protos/protos.pbserver.dart';
import 'dart:async';
import 'package:flutter/material.dart';
import 'package:barcode_scan/barcode_scan.dart';
import 'package:flutter/services.dart';
import 'package:qr_flutter/qr_flutter.dart';
class Scanner extends StatefulWidget {
@override
_ScannerState createState() => _ScannerState();
}
class _ScannerState extends State<Scanner> {
String result = "press the camera to start the scan !";
Future _scanQR() async {
try {
String qrResult = await BarcodeScanner.scan() as String;
setState(() {
result = qrResult;
});
} on PlatformException catch (ex) {
if (ex.code == BarcodeScanner.cameraAccessDenied) {
setState(() {
result = "Camera was denied";
});
} else {
setState(() {
result = "Unknown Error $ex";
});
}
} on FormatException {
setState(() {
result = "You pressed the back button before scanning anything";
});
} catch (ex) {
setState(() {
result = "Unknown Error $ex";
});
}
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text("QR Scanner"),
),
body: Center(
child: Text(
result,
style: new TextStyle(fontSize: 30.0, fontWeight: FontWeight.bold),
),
),
floatingActionButton: FloatingActionButton.extended(
icon: Icon(Icons.camera_alt),
label: Text("Scan"),
onPressed: _scanQR,
),
);
}
}
import'包:条形码扫描/gen/protos/protos.pbserver.dart';
导入“dart:async”;
进口“包装:颤振/材料.省道”;
导入“包装:条形码扫描/条形码扫描.dart”;
导入“包:flifter/services.dart”;
进口“包装:qr_颤振/qr_颤振.飞镖”;
类扫描程序扩展StatefulWidget{
@凌驾
_ScannerState createState();
}
类_ScannerState扩展状态{
String result=“按下相机开始扫描!”;
Future\u scanQR()异步{
试一试{
String qrResult=Wait BarcodeScanner.scan()作为字符串;
设置状态(){
结果=结果;
});
}平台上异常捕获(ex){
if(ex.code==BarcodeScanner.cameraAccessDenied){
设置状态(){
结果=“照相机被拒绝”;
});
}否则{
设置状态(){
结果=“未知错误$ex”;
});
}
}论格式例外{
设置状态(){
result=“您在扫描任何内容之前按下了后退按钮”;
});
}捕获(ex){
设置状态(){
结果=“未知错误$ex”;
});
}
}
@凌驾
小部件构建(构建上下文){
返回脚手架(
appBar:appBar(
标题:文本(“QR扫描仪”),
),
正文:中(
子:文本(
结果,,
样式:新的文本样式(fontSize:30.0,fontWeight:fontWeight.bold),
),
),
floatingActionButton:floatingActionButton.extended(
图标:图标(Icons.camera\u alt),
标签:文本(“扫描”),
按下按钮:_scanQR,
),
);
}
}
您可以使用rawContent
属性以字符串的形式访问数据:
ScanResult qrScanResult = await BarcodeScanner.scan();
String qrResult = qrScanResult.rawContent;
下面是完整的示例:
import 'package:barcode_scan/gen/protos/protos.pbserver.dart';
import 'dart:async';
import 'package:flutter/material.dart';
import 'package:barcode_scan/barcode_scan.dart';
import 'package:flutter/services.dart';
import 'package:qr_flutter/qr_flutter.dart';
class Scanner extends StatefulWidget {
@override
_ScannerState createState() => _ScannerState();
}
class _ScannerState extends State<Scanner> {
String result = "press the camera to start the scan !";
Future _scanQR() async {
try {
ScanResult qrScanResult = await BarcodeScanner.scan();
String qrResult = qrScanResult.rawContent;
setState(() {
result = qrResult;
});
} on PlatformException catch (ex) {
if (ex.code == BarcodeScanner.cameraAccessDenied) {
setState(() {
result = "Camera was denied";
});
} else {
setState(() {
result = "Unknown Error $ex";
});
}
} on FormatException {
setState(() {
result = "You pressed the back button before scanning anything";
});
} catch (ex) {
setState(() {
result = "Unknown Error $ex";
});
}
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text("QR Scanner"),
),
body: Center(
child: Text(
result,
style: new TextStyle(fontSize: 30.0, fontWeight: FontWeight.bold),
),
),
floatingActionButton: FloatingActionButton.extended(
icon: Icon(Icons.camera_alt),
label: Text("Scan"),
onPressed: _scanQR,
),
);
}
}
import'包:条形码扫描/gen/protos/protos.pbserver.dart';
导入“dart:async”;
进口“包装:颤振/材料.省道”;
导入“包装:条形码扫描/条形码扫描.dart”;
导入“包:flifter/services.dart”;
进口“包装:qr_颤振/qr_颤振.飞镖”;
类扫描程序扩展StatefulWidget{
@凌驾
_ScannerState createState();
}
类_ScannerState扩展状态{
String result=“按下相机开始扫描!”;
Future\u scanQR()异步{
试一试{
ScanResult qrScanResult=等待条形码扫描仪.scan();
字符串qresult=qrScanResult.rawContent;
设置状态(){
结果=结果;
});
}平台上异常捕获(ex){
if(ex.code==BarcodeScanner.cameraAccessDenied){
设置状态(){
结果=“照相机被拒绝”;
});
}否则{
设置状态(){
结果=“未知错误$ex”;
});
}
}论格式例外{
设置状态(){
result=“您在扫描任何内容之前按下了后退按钮”;
});
}捕获(ex){
设置状态(){
结果=“未知错误$ex”;
});
}
}
@凌驾
小部件构建(构建上下文){
返回脚手架(
appBar:appBar(
标题:文本(“QR扫描仪”),
),
正文:中(
子:文本(
结果,,
样式:新的文本样式(fontSize:30.0,fontWeight:fontWeight.bold),
),
),
floatingActionButton:floatingActionButton.extended(
图标:图标(Icons.camera\u alt),
标签:文本(“扫描”),
按下按钮:_scanQR,
),
);
}
}
非常感谢Stefano。它工作得很好:)很乐意帮忙!不要忘记选择正确的答案:)