一、依赖

dependencies:
  # permission 权限处理
  permission_handler: ^8.1.0

二、代码

import 'dart:developer';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:permission_handler/permission_handler.dart';

class PermissionUtil {
  BuildContext _context;

  PermissionUtil(this._context);

  //在检查之前可以去申请权限
  void checkPermission(PermissionStatus status, Permission permission) async {
    if (status.isDenied) {
      //拒绝了权限
      log("拒绝了权限");
      showPermissionRequestDialog('您拒绝了申请权限，但是该应用需要该权限，继续吗', permission, false);
    } else if (status.isPermanentlyDenied) {
      //永久拒绝了权限 提示用户
      log("永久拒绝了权限");
      showPermissionRequestDialog('您永久拒绝了权限，但是该应用需要该权限，继续吗', permission, true);
    } else {
      //通过权限申请
      log("通过权限申请...");
    }
  }

  void showPermissionRequestDialog(String message, Permission permission, bool gotoAppSettings) {
    showDialog(context: _context,
        builder: (context) {
          return AlertDialog(
            title: Text('权限申请'),
            content: Container(width: 200, child: Text(message),),
            actions: <Widget>[
              MaterialButton(onPressed: () {
                Navigator.of(context).pop();
              }, child: Text('取消')),
              MaterialButton(onPressed: () {
                Navigator.of(context).pop();
                if (gotoAppSettings){
                  openAppSettings() ;
                }else {
                  requestPermission(context, permission);
                }
              }, child: Text('确定')),
            ],
            actionsPadding: EdgeInsets.symmetric(horizontal: 8.0),
          );
        });
  }

  void requestPermission(BuildContext context, Permission permission) async{
    //请求权限
    PermissionStatus status = await permission.request();
    checkPermission(status, permission);
  }

  //关闭应用？？
  void closeApp(){
    SystemChannels.platform.invokeMethod("SystemNavigator.pop");
  }

}

三、使用

import 'package:flutter/material.dart';
import 'package:flutter_widgets/permission/permission_util.dart';
import 'package:permission_handler/permission_handler.dart';

class PermissionPage extends StatefulWidget {
  const PermissionPage({Key? key}) : super(key: key);

  @override
  _PermissionPageState createState() => _PermissionPageState();
}

class _PermissionPageState extends State<PermissionPage> {

  late PermissionUtil _permissionUtil;

  @override
  void initState() {
    super.initState();
    _permissionUtil = PermissionUtil(context);
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('权限请求'),),
      body: Container(
        child: Center(
          child: Column(
            children: [
              MaterialButton(
                  child: Text('申请权限'),
                  onPressed: () {
                    _permissionUtil.requestPermission(context, Permission.storage);
                  }),
              Text('请求权限结果:'),
            ],
          )
        ),
      ),
    );
  }

}