import io,,,,,,,

 

 

from https://pub.dev/packages/large_file_copy

Directory directory = await getApplicationDocumentsDirectory();var dbPath = join(directory.path, "app.db");if (FileSystemEntity.typeSync(dbPath) == FileSystemEntityType.notFound) {  ByteData data = await rootBundle.load("assets/my_db_file.db"); List
    
      bytes = data.buffer.asUint8List(data.offsetInBytes, data.lengthInBytes); await File(dbPath).writeAsBytes(bytes); }
    

 

var file1 = File(join(tempDir.path, '0/2048.apk')); var newFile = await file1.copy(join(tempDir.path, '4/1.apk'));

import 'package:flutter/material.dart';import 'dart:io';import 'dart:async';import 'package:rxdart/rxdart.dart';import 'package:path_provider/path_provider.dart';import 'package:path/path.dart';import 'package:permission_handler/permission_handler.dart';import 'package:flutter/services.dart';void main() => runApp(MaterialApp(home: MyApp(),));/*1. Copy aria2c executable to ``/mnt/sdcard`` on your device.2. Run Android Terminal Emulator.3. ``mkdir /data/data/jackpal.androidterm/aria2``4. ``cat /mnt/sdcard/aria2c > /data/data/jackpal.androidterm/aria2/aria2c``5. ``chmod 744 /data/data/jackpal.androidterm/aria2/aria2c``6. Add the following commands to the initial command of AndroidTerminal Emulator::export HOME=/data/data/jackpal.androidterm/aria2; cd $HOME7. Exit Android Terminal Emulator.8. Run Android Terminal Emulator again.9. See whether aria2c actually works by invoking ``./aria2c -v``*/class MyApp extends StatelessWidget {  DataBloc bloc;  checkPermission()async{    var per = await PermissionHandler().checkPermissionStatus(PermissionGroup.storage);    if(per!=PermissionStatus.granted){      await PermissionHandler().requestPermissions([PermissionGroup.storage]);    }  }  cp()async{    await checkPermission();    Directory tempDir = await getExternalStorageDirectory();    String workDir = join(tempDir.path, '4');//    var p = await Process.run('mkdir', [workDir]).then((ProcessResult e){//      print(e.stderr);//      print(e.exitCode);//    });    var file1 = await rootBundle.load('assets/aria2c');    var buf = file1.buffer;    File(join(workDir, 'xxx')).writeAsBytesSync(buf.asUint8List());//    var newFile = await file1.copy(join(tempDir.path, '4/1.apk'));    print('done');  }  @override  Widget build(BuildContext context) {    return Scaffold(      appBar: AppBar(title: Text('sss'),),      body: Container(        child: Column(          mainAxisAlignment: MainAxisAlignment.center,          crossAxisAlignment: CrossAxisAlignment.center,          children: 
     
      [            RaisedButton(child: Text('mkdir'),onPressed: (){                cp();            },),            RaisedButton(child: Text('delete'),onPressed: (){            },),            Container(                width: 50,height: 50,child: Image(image: AssetImage('assets/img/a.png',),fit: BoxFit.cover,)),//            Container(//                width: 50, height: 50,child: Text('   '),decoration: BoxDecoration(//              image: DecorationImage(image: AssetImage('assets/img/a.png')),//            ),),          ],        ),      ),    );  }}class DataBloc {  ReplaySubject dataBloc = ReplaySubject();}//void shell(String cmd, List
      
        opts, void onExit(int exitCode))async{//  var p = await Process.start(cmd, opts);//  p.stdout.pipe(stdout);//  stdin.pipe(p.stdin);//  p.onExit = (exitCode)async{//    await p.kill();//    onExit(exitCode);//  }//}//void shell(String cmd, List
       
         opts, void onExit(int exitCode)) {//  var p = Process.start(cmd, opts);//  p.stdout.pipe(stdout);  // Process output to stdout.//  stdin.pipe(p.stdin);    // stdin to process input.//  p.onExit = (exitCode) {//    p.close();//    onExit(exitCode);//  };//}