#生成二维码

##首先需要在pubspec.yaml:中添加

qr_flutter: ^1.1.3

其次，引入代码：

import 'package:qr_flutter/qr_flutter.dart';

核心代码如下：

        child: QrImage(data: "这里是需要生成二维码的数据",size: 100.0,onError: (ex) {print("[QR] ERROR - $ex");},
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整体代码与效果如下：

#识别二维码

这里也用第三方的包在pubspec.yaml中添加库链接；

barcode_scan: ^0.0.4

识别的主要代码如下：

  Future scan() async {try {String barcode = await BarcodeScanner.scan();setState(() {return this.barcode = barcode;});} on PlatformException catch (e) {if (e.code == BarcodeScanner.CameraAccessDenied) {setState(() {return this.barcode = 'The user did not grant the camera permission!';});} else {setState(() {return this.barcode = 'Unknown error: $e';});}} on FormatException{setState(() => this.barcode = 'null (User returned using the "back"-button before scanning anything. Result)');} catch (e) {setState(() => this.barcode = 'Unknown error: $e');}}
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整体代码如下：

import 'package:flutter/material.dart';
import 'package:barcode_scan/barcode_scan.dart';
import 'dart:async';
import 'package:flutter/services.dart';class scanqr extends StatelessWidget {@overrideWidget build(BuildContext context) {// TODO: implement buildreturn MaterialApp(home: sacnBody(),);}
}class sacnBody extends StatefulWidget {
@overrideState<StatefulWidget> createState() {// TODO: implement createStatereturn _MyScanState();}
}class _MyScanState extends State<sacnBody> {String barcode = "";@overridevoid initState() {// TODO: implement initStatesuper.initState();}@overrideWidget build(BuildContext context) {// TODO: implement buildreturn Scaffold(appBar: new AppBar(title: new Text('QR Code'),),body: new Center(child: new Column(mainAxisAlignment: MainAxisAlignment.center,crossAxisAlignment: CrossAxisAlignment.stretch,children: <Widget>[Padding(padding: EdgeInsets.symmetric(horizontal: 15.0,vertical: 8.0),child: RaisedButton(color: Colors.orange,textColor: Colors.white,splashColor: Colors.blueGrey,onPressed: scan,child: const Text('START CAMERA SCAN')),),Padding (padding: EdgeInsets.symmetric(horizontal: 16.0, vertical: 8.0),child: Text(barcode, textAlign: TextAlign.center,),)],),),);}Future scan() async {try {String barcode = await BarcodeScanner.scan();setState(() {return this.barcode = barcode;});} on PlatformException catch (e) {if (e.code == BarcodeScanner.CameraAccessDenied) {setState(() {return this.barcode = 'The user did not grant the camera permission!';});} else {setState(() {return this.barcode = 'Unknown error: $e';});}} on FormatException{setState(() => this.barcode = 'null (User returned using the "back"-button before scanning anything. Result)');} catch (e) {setState(() => this.barcode = 'Unknown error: $e');}}}
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安卓和iOS工程设置如下：

Android For Android, you must do the following before you can use the plugin:

Add the camera permission to your AndroidManifest.xml<uses-permission android:name="android.permission.CAMERA" />Add the Barcode activity to your AndroidManifest.xml<activity android:name="com.apptreesoftware.barcodescan.BarcodeScannerActivity"/>
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iOS To use on iOS, you must add the the camera usage description to your Info.plist

<key>NSCameraUsageDescription</key>
<string>Camera permission is required for barcode scanning.</string>
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