c# - 从 WindowsPhone 8.1 调用 GetDiskFreeSpaceExW api

Question

我试图在我的 Windows Phone 8.1 应用程序中调用 GetDiskFreeSpaceExW Win Api 调用，但我总是无法通过认证。

此函数在支持的 Win32 API 列表中: https://msdn.microsoft.com/en-us/library/windows/apps/jj662956(v=vs.105).aspx#BKMK_ListofsupportedWin32APIs

我的电话:

        [DllImport("api-ms-win-core-file-l1-2-0.dll", SetLastError = true)]
        static extern bool GetDiskFreeSpaceEx(string lpDirectoryName,
                                              out ulong lpFreeBytesAvailable,
                                              out ulong lpTotalNumberOfBytes,
                                              out ulong lpTotalNumberOfFreeBytes);

错误:

This API is not supported for this application type - Api=GetDiskFreeSpaceEx. Module=api-ms-win-core-file-l1-2-0.dll. File=Glide.WindowsCommon.dll.

我在这里错过了什么？

Answer 1

[DllImport("api-ms-win-core-file-l1-2-0.dll", SetLastError = true)]
static extern bool GetDiskFreeSpaceEx(string lpDirectoryName,
                                      out ulong lpFreeBytesAvailable,
                                      out ulong lpTotalNumberOfBytes,
                                      out ulong lpTotalNumberOfFreeBytes);

因为您没有指定 CharSet 值，所以默认使用 CharSet.Ansi 的 CharSet 进行编码。您应该像这样指定 CharSet.Unicode:

[DllImport("api-ms-win-core-file-l1-2-0.dll", CharSet = CharSet.Unicode, 
    SetLastError = true)]
static extern bool GetDiskFreeSpaceEx(...);

看来认证过程还需要显式声明入口点名称:

[DllImport("api-ms-win-core-file-l1-2-0.dll", CharSet = CharSet.Unicode, 
    Entry point = "GetDiskFreeSpaceExW", SetLastError = true)]
static extern bool GetDiskFreeSpaceEx(...);