Question

我对飞镖/打靶还很陌生，所以让我知道是否有什么可以澄清的。我正在尝试下载文件，但是当我尝试访问它时，出现错误“ FileSystemException：无法打开文件，路径='./data.csv'（操作系统错误：只读文件系统，errno = 30 ）“我在做什么错了，我该如何解决？

 downloadTextFile() {
    HttpClient client = new HttpClient();
    client.getUrl(Uri.parse(*I put the link I used here, but it's sort of long*))
        .then((HttpClientRequest request) {
      return request.close();
    })
        .then((HttpClientResponse response) {
      response.pipe(new File('./data.csv').openWrite());
    });
    readFileByLines();
  }

  void readFileByLines() {
    File file = new File('./data.csv');
    List<String> lines = file.readAsLinesSync();
    lines.forEach((l) => print(l));
  }

Answer 1

您可以使用软件包https://pub.dev/packages/path_provider
并将您的文件写入appDocPath或Directory tempDir = await getTemporaryDirectory(); String tempPath = tempDir.path; Directory appDocDir = await getApplicationDocumentsDirectory(); String appDocPath = appDocDir.path;

AndroidManifest.xml

对于Android，在<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/> <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>中，您可以添加权限

Select * from 
(
SELECT 
    OrderDet.PartNo
    ,COUNT(OrderDet.PartNo) AS [Number Of Orders]
    ,SUM(OrderDet.QtyToMake) AS [Total to Make]
FROM 
    OrderDet
WHERE 
    OrderDet.Status = 'Open' 
    AND OrderDet.PartNo = 'SomePartNumber'
GROUP BY 
    OrderDet.PartNo
) t
JOIN
(
SELECT 
    SUM(BinLocations.QtyOnHand) AS [Total Available]
    ,PartNo
FROM 
    BinLocations
WHERE 
    BinLocations.PartNo = 'SomePartNumber'
GROUP BY 
    BinLocations.PartNo
) t1
ON t.PartNo = t1.PartNo;

读写文件时如何解决“ FileSystemException：无法打开文件”问题？

1 个答案: