안드로이드 5.x 이상버전엔 권한부여 확인하여 부여 받을수 있다.

    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
    <uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW" />
    <uses-permission android:name="android.permission.ACCESS_BACKGROUND_SERVICE" />
    <uses-permission android:name="android.permission.WAKE_LOCK" />
    <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED"/>

원하는 권한 옵션 선택하여 앱 실행시 요청한다.


        //권한이 부여되어 있는지 확인
        int permissonCheck= ContextCompat.checkSelfPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE);
        if(permissonCheck == PackageManager.PERMISSION_GRANTED){
        }else{
            Toast.makeText(getApplicationContext(), "저장공간 액세스권한 없음", Toast.LENGTH_SHORT).show();
            if(ActivityCompat.shouldShowRequestPermissionRationale(this, Manifest.permission.READ_EXTERNAL_STORAGE)){
                Toast.makeText(getApplicationContext(), "저장공간 액세스권한이 필요합니다", Toast.LENGTH_SHORT).show();
                ActivityCompat.requestPermissions(this, new String[]{ Manifest.permission.READ_EXTERNAL_STORAGE}, PERMISSIONS_REQUEST_RESULT);
            }else{
                ActivityCompat.requestPermissions(this, new String[]{ Manifest.permission.READ_EXTERNAL_STORAGE}, PERMISSIONS_REQUEST_RESULT);
            }
        }


    @Override
    public void onRequestPermissionsResult(int requestCode, String permissions[], int grantResults[]){
        switch(requestCode){
            case PERMISSIONS_REQUEST_RESULT :
                if(grantResults.length>0 && grantResults[0]== PackageManager.PERMISSION_GRANTED){
                    Toast.makeText(getApplicationContext(), "저장공간 액세스권한 승인함", Toast.LENGTH_SHORT).show();
                }else{
                    Toast.makeText(getApplicationContext(), "저장공간 액세스권한 거부함", Toast.LENGTH_SHORT).show();
                }
                break;
        }
    }