C#如何通过权限类和权限属性来修改安全权限的代码

工作过程中中，把写内容过程中重要的内容段备份一下，如下的内容是关于C#如何通过权限类和权限属性来修改安全权限的内容，应该对大伙有些用途。

using System;
using System.Security;
using System.Security.Permissions;
using System.Runtime.InteropServices;

class NativeMethods
{
    [DllImport("msvcrt.dll")]
    public static extern int puts(string str);
    [DllImport("msvcrt.dll")]
    internal static extern int _flushall();
}

class MainClass
{
    private static void CallUnmanagedCodeWithoutPermission()
    {
        SecurityPermission perm = 
           new SecurityPermission(SecurityPermissionFlag.UnmanagedCode);

        perm.Deny();

        try
        {
            Console.WriteLine("Attempting to call unmanaged code without permission.");
            NativeMethods.puts("Hello World!");
            NativeMethods._flushall();
            Console.WriteLine("Called unmanaged code without permission. Whoops!");
        }
        catch (SecurityException)
        {
            Console.WriteLine("Caught Security Exception attempting to call unmanaged code.");
        }
    }

    private static void CallUnmanagedCodeWithPermission()
    {
        SecurityPermission perm = 
           new SecurityPermission(SecurityPermissionFlag.UnmanagedCode);

        perm.Assert();

        try
        {
            Console.WriteLine("Attempting to call unmanaged code with permission.");
            NativeMethods.puts("Hello World!");
            NativeMethods._flushall();
            Console.WriteLine("Called unmanaged code with permission.");
        }
        catch (SecurityException)
        {
            Console.WriteLine("Caught Security Exception attempting to call unmanaged code. Whoops!");
        }
    }

    public static void Main() 
    {
        SecurityPermission perm = new 
            SecurityPermission(SecurityPermissionFlag.UnmanagedCode);
        perm.Assert();
        CallUnmanagedCodeWithoutPermission();

        perm.Deny();
        CallUnmanagedCodeWithPermission();
    }
}

using System;
using System.Security;
using System.Security.Permissions;
using System.Runtime.InteropServices;

class NativeMethods
{
    [DllImport("msvcrt.dll")]
    public static extern int puts(string str);
    [DllImport("msvcrt.dll")]
    internal static extern int _flushall();
}

class MainClass
{
    [SecurityPermission(SecurityAction.Deny, Flags = 
       SecurityPermissionFlag.UnmanagedCode)]
    private static void CallUnmanagedCodeWithoutPermission()
    {
        try
        {
            Console.WriteLine("Attempting to call unmanaged code without permission.");
            NativeMethods.puts("Hello World!");
            NativeMethods._flushall();
            Console.WriteLine("Called unmanaged code without permission. Whoops!");
        }
        catch (SecurityException)
        {
            Console.WriteLine("Caught Security Exception attempting to call unmanaged code.");
        }
    }

    [SecurityPermission(SecurityAction.Assert, Flags = 
       SecurityPermissionFlag.UnmanagedCode)]
    private static void CallUnmanagedCodeWithPermission()
    {
        try
        {
            Console.WriteLine("Attempting to call unmanaged code with permission.");
            NativeMethods.puts("Hello World!");
            NativeMethods._flushall();
            Console.WriteLine("Called unmanaged code with permission.");
        }
        catch (SecurityException)
        {
            Console.WriteLine("Caught Security Exception attempting to call unmanaged code. Whoops!");
        }
    }

    public static void Main() 
    {
        SecurityPermission perm = new
            SecurityPermission(SecurityPermissionFlag.UnmanagedCode);

        perm.Assert();
        CallUnmanagedCodeWithoutPermission();

        perm.Deny();
        CallUnmanagedCodeWithPermission();
    }
}

using System;
using System.Security;
using System.Security.Permissions;
using System.Runtime.InteropServices;

class NativeMethods
{
    [SuppressUnmanagedCodeSecurityAttribute()]
    [DllImport("msvcrt.dll")]
    internal static extern int puts(string str);
    [SuppressUnmanagedCodeSecurityAttribute()]
    [DllImport("msvcrt.dll")]
    internal static extern int _flushall();
}

class MainClass
{
    [SecurityPermission(SecurityAction.Deny, Flags = 
       SecurityPermissionFlag.UnmanagedCode)]
    private static void CallUnmanagedCodeWithoutPermission()
    {
        try
        {
            UIPermission uiPermission = 
               new UIPermission(PermissionState.Unrestricted);
            uiPermission.Demand();

            Console.WriteLine("Attempting to call unmanaged code without UnmanagedCode permission.");
            NativeMethods.puts("Hello World!");
            NativeMethods._flushall();
            Console.WriteLine("Called unmanaged code without UnmanagedCode permission.");
        }
        catch (SecurityException)
        {
            Console.WriteLine("Caught Security Exception attempting to call unmanaged code.");
        }
    }

    [SecurityPermission(SecurityAction.Assert, Flags = 
       SecurityPermissionFlag.UnmanagedCode)]
    private static void CallUnmanagedCodeWithPermission()
    {
        try
        {
            Console.WriteLine("Attempting to call unmanaged code with permission.");
            NativeMethods.puts("Hello World!");
            NativeMethods._flushall();
            Console.WriteLine("Called unmanaged code with permission.");
        }
        catch (SecurityException)
        {
            Console.WriteLine("Caught Security Exception attempting to call unmanaged code. Whoops!");
        }
    }

    public static void Main() 
    {
        SecurityPermission perm = new
            SecurityPermission(SecurityPermissionFlag.UnmanagedCode);

       perm.Assert();
       CallUnmanagedCodeWithoutPermission();

       perm.Deny();
       CallUnmanagedCodeWithPermission();
    }
}