Android6.0 申请SYSTEM_ALERT_WINDOW权限 没有弹出权限框

问题：在Android6.0申请SYSTEM_ALERT_WINDOW权限，没有弹授权框？
解决：在android6.0应用开发时，动态申请权限时。按照官方文档无法申请到SYSTEM_ALERT_WINDOW权限，爬stackoverflow找到解决方案。
这个好像是一个bug，可以使用层叠权限解决【Settings.ACTION_MANAGE_OVERLAY_PERMISSION】。
解释博客

直接上代码：

private void checkPermissions(){        Log.d("MainActivity->","SDK_INT->"+Build.VERSION.SDK_INT);        if(Build.VERSION.SDK_INT< 23){            return ;        }        /*        检查是否有悬浮窗的权限         */        if (!Settings.canDrawOverlays(this)) {            isHasAlertPermission = false;            Intent intent = new Intent(Settings.ACTION_MANAGE_OVERLAY_PERMISSION,                    Uri.parse("package:" + getPackageName()));            startActivityForResult(intent, 101);        }        /*        无效的方法,可以申请读取联系人的权限        */        int hasPermission = checkSelfPermission(Manifest.permission.READ_CONTACTS);        if(PackageManager.PERMISSION_GRANTED !=hasPermission){            Log.d("MainActivity->","get permissions"+Build.VERSION.SDK_INT);            requestPermissions(new String[]{Manifest.permission.SYSTEM_ALERT_WINDOW},100);        }    }

/**申请联系人等权限回调*/@Override    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {        switch (requestCode){            case 100:                if(PackageManager.PERMISSION_GRANTED == grantResults[0]){                    isHasAlertPermission = true;                }else {                    Toast.makeText(MainActivity.this,"没有获取权限",Toast.LENGTH_LONG).show();                }                break;            default:                super.onRequestPermissionsResult(requestCode, permissions, grantResults);        }    }    /**    跳转到设置可以悬浮的权限    **/    @Override    protected void onActivityResult(int requestCode, int resultCode, Intent data) {        switch (requestCode){            case 101:                if(Build.VERSION.SDK_INT >22){                    if (!Settings.canDrawOverlays(this)){                        isHasAlertPermission = false;                    }                    else {                        isHasAlertPermission =true;                    }                }                break;            default:                super.onActivityResult(requestCode, resultCode, data);        }    }