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[英]Access is denied when trying to CreateFileAsync in InstalledLocation StorageFolder?
[英]What's happen when CreateFileAsync write file to a disk which Write access denied or capacity shortage
我编写了一个提供下载文件功能的类,使用CreateFileAsync创建文件,然后使用WriteBytesAsync写入下载的每个字节。 如果目标磁盘被拒绝写入或容量不足,WriteBytesAsync或CreateFileAsync是否会引发任何异常?
谢谢。
如果磁盘具有写保护,则在创建文件时可能会生成UnauthorizedAccessException
。 我建议您检查磁盘驱动器中是否有可用空间。 使用以下给定的方法获取磁盘驱动器的可用空间和容量。
public static class StorageItemExtensions
{
public static async Task<IDictionary<string, object>> GetSpace(this IStorageItem sf)
{
var properties = await sf.GetBasicPropertiesAsync();
return await properties.RetrievePropertiesAsync(new[] { "System.FreeSpace", "System.Capacity" });
}
public static string GetSizeString(this ulong sizeInB, double promoteLimit = 1024, double decimalLimit = 10, string separator = " ")
{
if (sizeInB < promoteLimit)
return string.Format("{0}{1}B", sizeInB, separator);
var sizeInKB = sizeInB / 1024.0;
if (sizeInKB < decimalLimit)
return string.Format("{0:F2}{1}KB", sizeInKB, separator);
if (sizeInKB < promoteLimit)
return string.Format("{0:F2}{1}KB", sizeInKB, separator);
var sizeInMB = sizeInKB / 1024.0;
if (sizeInMB < decimalLimit)
return string.Format("{0:F2}{1}MB", sizeInMB, separator);
if (sizeInMB < promoteLimit)
return string.Format("{0:F2}{1}MB", sizeInMB, separator);
var sizeInGB = sizeInMB / 1024.0;
if (sizeInGB < decimalLimit)
return string.Format("{0:F2}{1}GB", sizeInGB, separator);
if (sizeInGB < promoteLimit)
return string.Format("{0:F2}{1}GB", sizeInGB, separator);
var sizeInTB = sizeInGB / 1024.0;
if (sizeInTB < decimalLimit)
return string.Format("{0:F2}{1}TB", sizeInTB, separator);
return string.Format("{0:F2}{1}TB", sizeInTB, separator);
}
}
用法:
var filteredProperties = await ApplicationData.Current.LocalFolder.GetSpace();
var diskSpace = ((UInt64)filteredProperties["System.FreeSpace"]).GetSizeString() + " / " + ((UInt64)filteredProperties["System.Capacity"]).GetSizeString();
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