Question

我编写了一个提供下载文件功能的类，我使用CreateFileAsync创建文件，然后使用WriteBytesAsync写入下载的每个字节。如果目标磁盘是写入拒绝或容量不足，WriteBytesAsync或CreateFileAsync是否会抛出任何异常？

谢谢。

Answer 1

如果磁盘被写保护，则在创建文件时可能会生成UnauthorizedAccessException。我建议你检查磁盘驱动器中是否有空闲空间。使用下面给出的方法来获得自由空间＆amp;磁盘驱动器的容量。

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();

当CreateFileAsync将文件写入写入拒绝写入或容量不足的磁盘时会发生什么

1 个答案: