我正在使用下载管理器将文件下载到手机存储上的新文件夹中。这是我使用的代码:DownloadManager.RequestdownloadSample=newDownloadManager.Request(Uri.parse(urlSample));downloadSample.allowScanningByMediaScanner();downloadSample.setDestinationInExternalPublicDir("/Samples/"+previewName,"sample.ttf");downloadSample.setNotificationVisibility

我遇到了这个异常:10-2417:08:19.711:E/AndroidRuntime(1379):FATALEXCEPTION:main10-2417:08:19.711:E/AndroidRuntime(1379):java.lang.RuntimeException:UnabletostartactivityComponentInfo{br.com.campusfqm.cfqm/br.com.campusfqm.cfqm.DownloadManagerActivity}:java.lang.IllegalStateException:Unabletocreatedirectory