ASP.Net中的SafeHandle类可用于管理外部资源，如文件句柄、内存句柄等。下面是一些使用SafeHandle的示例：

1. 管理文件句柄

public class FileSafeHandle : SafeHandleZeroOrMinusOneIsInvalid
{
    private readonly string _fileName;

    [DllImport("kernel32.dll", CharSet = CharSet.Unicode, SetLastError = true)]
    private static extern IntPtr CreateFile(
        string lpFileName,
        FileAccess dwDesiredAccess,
        FileShare dwShareMode,
        IntPtr lpSecurityAttributes,
        FileMode dwCreationDisposition,
        FileAttributes dwFlagsAndAttributes,
        IntPtr hTemplateFile);

    public FileSafeHandle(string fileName)
        : base(true)
    {
        _fileName = fileName;
        handle = CreateFile(fileName, FileAccess.ReadWrite, FileShare.ReadWrite, IntPtr.Zero,
            FileMode.Open, FileAttributes.RandomAccess, IntPtr.Zero);
        if (handle == IntPtr.Zero || handle == new IntPtr(-1))
        {
            int lastWin32Error = Marshal.GetLastWin32Error();
            throw new Win32Exception(lastWin32Error, "Failed to open file");
        }
    }

    protected override bool ReleaseHandle()
    {
        return NativeMethods.CloseHandle(handle);
    }

    public string FileName => _fileName;
}

在使用FileSafeHandle时，只需像使用一般的文件句柄一样使用即可，无需手动释放句柄。

2. 管理内存句柄

public class MemorySafeHandle : SafeHandleZeroOrMinusOneIsInvalid
{
    private readonly long _memorySize;

    [DllImport("kernel32.dll", SetLastError = true)]
    private static extern IntPtr VirtualAlloc(IntPtr lpAddress, UIntPtr dwSize,
        AllocationType flAllocationType, MemoryProtection flProtect);

    [DllImport("kernel32.dll", SetLastError = true)]
    private static extern bool VirtualFree(IntPtr lpAddress, UIntPtr dwSize,
        FreeType dwFreeType);

    public MemorySafeHandle(long memorySize)
        : base(true)
    {
        _memorySize = memorySize;
        handle = VirtualAlloc(IntPtr.Zero, new UIntPtr((ulong)memorySize),
            Allocation