使用ASP.NET Core下载文件

Question

我在创建文件后尝试下载excel文件,并且出现以下错误:

UnauthorizedAccessException:拒绝访问路径'C:\ Users\user_name\Documents\Visual Studio 2015\Projects\Project_Name\src\Project_Name\wwwroot'.

该文件已成功创建,问题出在下载方法中.

我已经尝试解决此错误,执行以下操作:

• 打开VS作为管理员
• 将IIS_IUSR用户添加到项目文件夹

这是代码:

    private readonly IHostingEnvironment _hostingEnvironment;
    public EmployeeController(ApplicationDbContext context, IHostingEnvironment hostingEnvironment)
    {
        _hostingEnvironment = hostingEnvironment;
    }
    public void createFile()
    {
        string wwwrootPath = _hostingEnvironment.WebRootPath;
        string fileName = @"Employees.xlsx";
        FileInfo file = new FileInfo(Path.Combine(wwwrootPath, fileName));

        if (file.Exists)
        {
            file.Delete();
            file = new FileInfo(Path.Combine(wwwrootPath, fileName));
        }
        using (ExcelPackage package = new ExcelPackage(file))
        {
            ExcelWorksheet worksheet = package.Workbook.Worksheets.Add("Employee");
            worksheet.Cells[1, 1].Value = "ID";
            worksheet.Cells[1, 2].Value = "Name";
            worksheet.Cells[1, 3].Value = "Gender";
            worksheet.Cells[1, 4].Value = "Salary (in $)";

            worksheet.Cells["A2"].Value = 1000;
            worksheet.Cells["B2"].Value = "Jon";
            worksheet.Cells["C2"].Value = "M";
            worksheet.Cells["D2"].Value = 5000;

            worksheet.Cells["A3"].Value = 1001;
            worksheet.Cells["B3"].Value = "Graham";
            worksheet.Cells["C3"].Value = "M";
            worksheet.Cells["D3"].Value = 10000;

            worksheet.Cells["A4"].Value = 1002;
            worksheet.Cells["B4"].Value = "Jenny";
            worksheet.Cells["C4"].Value = "F";
            worksheet.Cells["D4"].Value = 5000;

            package.Save(); 
            downloadFile(wwwrootPath);

        }  

}
    public FileResult downloadFile(string filePath)
    {
        var mimeType = "application/vnd.ms-excel";
        FileStream fileStream = new FileStream(filePath, FileMode.Open, FileAccess.Read);

        return File(fileStream, mimeType, "Employees.xlsx");
    }

注意:我没有在IIS中部署项目.

最好的祝福

Answer 1

在ASP.NET Core中，您应该使用PhysicalFileProvider类来访问实际系统的文件。如果您查看文档中的“ 文件提供者”部分：

PhysicalFileProvider提供对物理文件系统的访问。它包装System.IO.File类型（用于物理提供程序），对目录及其子目录的所有路径进行范围界定。这种作用域限制了对某个目录及其子目录的访问，从而阻止了对该边界之外文件系统的访问。

以下应该为您工作：

string wwwrootPath = _hostingEnvironment.WebRootPath;
string fileName = @"Employees.xlsx";

IFileProvider provider = new PhysicalFileProvider(wwwrootPath);
IFileInfo fileInfo = provider.GetFileInfo(fileName);
var readStream = fileInfo.CreateReadStream();

// PhysicalFileProvider.GetFileInfo返回PhysicalFileInfo提供IFileInfo.CreateReadStream方法实现的实例。