EnvironmentPermission 类
控制对系统和用户环境变量的访问。无法继承此类。
**命名空间:**System.Security.Permissions
**程序集:**mscorlib（在 mscorlib.dll 中）
语法
声明
<SerializableAttribute> _
<ComVisibleAttribute(True)> _
Public NotInheritable Class EnvironmentPermission
Inherits CodeAccessPermission
Implements IUnrestrictedPermission
用法
Dim instance As EnvironmentPermission
[SerializableAttribute]
[ComVisibleAttribute(true)]
public sealed class EnvironmentPermission : CodeAccessPermission, IUnrestrictedPermission
[SerializableAttribute]
[ComVisibleAttribute(true)]
public ref class EnvironmentPermission sealed : public CodeAccessPermission, IUnrestrictedPermission
/** @attribute SerializableAttribute() */
/** @attribute ComVisibleAttribute(true) */
public final class EnvironmentPermission extends CodeAccessPermission implements IUnrestrictedPermission
SerializableAttribute
ComVisibleAttribute(true)
public final class EnvironmentPermission extends CodeAccessPermission implements IUnrestrictedPermission
备注
环境变量名由一个或多个不区分大小写的名称列表指定，这些列表以分号分隔，每个列表分别对应于不同命名变量的读写访问权限。写访问权限不仅包括写现有值的能力，还包括创建和删除环境变量的能力。
警告
EnvironmentPermission 授予对环境变量及其值的访问权限。若要拒绝对变量及其值的访问，则必须拒绝对此变量的访问，并且还必须拒绝对其他包含相同值的变量的访问。例如，若要 Deny 对 TMP 变量及其值 %USERPROFILE%\Local Settings\Temp 的访问，则必须 Deny 对 TMP、TEMP 以及任何其他可以用来访问该值的变量的访问。处理多路径的更好方法是结合使用 PermitOnly 和 Deny。有关此主题以及如何结合使用 PermitOnly 和 Deny 的更多信息，请参见 使用 Deny 方法 中的“使用拒绝的规范化问题”。
示例
下面的代码示例演示 EnvironmentPermission 方法的行为。该示例的目的是演示方法的结果，而不演示如何使用这些方法。
Imports System
Imports System.Security
Imports System.Security.Permissions
Imports System.Collections
Public Class EnvironmentPermissionDemo
' IsSubsetOf determines whether the current permission is a subset of the specified permission.
Private Function IsSubsetOfDemo() As Boolean
Dim returnValue As Boolean = True
Dim envPerm1 As New EnvironmentPermission(EnvironmentPermissionAccess.Read, "windir")
Dim envPerm2 As New EnvironmentPermission(EnvironmentPermissionAccess.AllAccess, "TEMP")
If envPerm1.IsSubsetOf(envPerm2) Then
Console.WriteLine("'windir' is a subset of 'TEMP'" + vbLf)
Else
Console.WriteLine("windir" + " is not a subset of " + "TEMP" + vbLf)
End If
envPerm1.SetPathList(EnvironmentPermissionAccess.Read, "TEMP")
If envPerm1.IsSubsetOf(envPerm2) Then
Console.WriteLine("Read access is a subset of AllAccess" + vbLf)
Else
Console.WriteLine("Read access is not a subset of AllAccess" + vbLf)
End If
Return returnValue
End Function 'IsSubsetOfDemo
' Union creates a new permission that is the union of the current permission and the specified permission.
Private Function UnionDemo() As Boolean
Dim returnValue As Boolean = True
Dim envIdPerm3 As IPermission
Dim envPerm1 As New EnvironmentPermission(EnvironmentPermissionAccess.Read, "windir")
Dim envPerm2 As New EnvironmentPermission(EnvironmentPermissionAccess.Read, "TEMP")
envIdPerm3 = CType(envPerm1.Union(envPerm2), EnvironmentPermission)
envIdPerm3 = envPerm1.Union(envPerm2)
Console.WriteLine("The union of 'windir' and 'TEMP'" + " = " + _
CType(envIdPerm3, EnvironmentPermission).GetPathList(EnvironmentPermissionAccess.Read).ToString())
Return returnValue
End Function 'UnionDemo
' Intersect creates and returns a new permission that is the intersection of
' the current permission and the permission specified.
Private Function IntersectDemo() As Boolean
Dim envIdPerm3 As IPermission
Dim returnValue As Boolean = True
Dim envPerm1 As New EnvironmentPermission(EnvironmentPermissionAccess.Read, "windir")
Dim envPerm2 As New EnvironmentPermission(EnvironmentPermissionAccess.Read, "TEMP")
Try
envIdPerm3 = CType(envPerm1.Intersect(envPerm2), EnvironmentPermission)
If Not (envIdPerm3 Is Nothing) AndAlso Not (CType(envIdPerm3, _
EnvironmentPermission).GetPathList(EnvironmentPermissionAccess.Read) Is Nothing) Then
Console.WriteLine("The intersection of " + "windir" + " and " + "TEMP" + _
" = " + CType(envIdPerm3, EnvironmentPermission).GetPathList(EnvironmentPermissionAccess.Read).ToString())
Else
Console.WriteLine("The intersection of " + "windir" + " and " + "TEMP" + " is null.")
End If
Catch e As Exception
Console.WriteLine("An exception was thrown for intersection : " + e.Message)
returnValue = False
End Try
Return returnValue
End Function 'IntersectDemo
'Copy creates and returns an identical copy of the current permission.
Private Function CopyDemo() As Boolean
Dim returnValue As Boolean = True
Dim envPerm1 As New EnvironmentPermission(EnvironmentPermissionAccess.Read, "windir")
Try
Dim envPerm2 As EnvironmentPermission = CType(envPerm1.Copy(), EnvironmentPermission)
If Not (envPerm2 Is Nothing) Then
Console.WriteLine("Result of copy = " + envPerm2.ToString() + vbLf)
Else
Console.WriteLine("Result of copy is null. " + vbLf)
End If
Catch e As Exception
Console.WriteLine(e)
End Try
Return returnValue
End Function 'CopyDemo
' ToXml creates an XML encoding of the permission and its current state; FromXml reconstructs
' a permission with the specified state from the XML encoding.
Private Function ToFromXmlDemo() As Boolean
Dim returnValue As Boolean = True
Dim envPerm1 As New EnvironmentPermission(EnvironmentPermissionAccess.Read, "windir")
Dim envPerm2 As New EnvironmentPermission(PermissionState.None)
envPerm2.FromXml(envPerm1.ToXml())
Console.WriteLine("Result of ToFromXml = " + envPerm2.ToString() + vbLf)
Return returnValue
End Function 'ToFromXmlDemo
' AddPathList adds access for the specified environment variables to the existing state of the permission.
' SetPathList Sets the specified access to the specified environment variables to the existing state
' of the permission.
' GetPathList gets all environment variables with the specified EnvironmentPermissionAccess.
Private Function SetGetPathListDemo() As Boolean
Try
Console.WriteLine("********************************************************" + vbLf)
Console.WriteLine("Creating an EnvironmentPermission with AllAccess rights for 'TMP'")
Dim envPerm1 As New EnvironmentPermission(EnvironmentPermissionAccess.AllAccess, "TMP")
Console.WriteLine("Adding 'TEMP' to the write access list, and 'windir' to the read access list.")
envPerm1.AddPathList(EnvironmentPermissionAccess.Write, "TEMP")
envPerm1.AddPathList(EnvironmentPermissionAccess.Read, "windir")
Console.WriteLine("Read access list before SetPathList = " + envPerm1.GetPathList(EnvironmentPermissionAccess.Read))
Console.WriteLine("Setting read access to 'TMP'")
envPerm1.SetPathList(EnvironmentPermissionAccess.Read, "TMP")
Console.WriteLine("Read access list after SetPathList = " + envPerm1.GetPathList(EnvironmentPermissionAccess.Read))
Console.WriteLine("Write access list = " + envPerm1.GetPathList(EnvironmentPermissionAccess.Write))
Console.WriteLine("Write access environment variables = " + envPerm1.GetPathList(EnvironmentPermissionAccess.AllAccess))
Catch e As ArgumentException
' EnvironmentPermissionAccess.AllAccess cannot be used as a parameter for GetPathList.
Console.WriteLine("An ArgumentException occurred as a result of using AllAccess. " + _
" This property cannot be used as a parameter in GetPathList, because it represents " + _
"more than one type of environment variable : " + vbLf + e.Message)
End Try
Return True
End Function 'SetGetPathListDemo
' Invoke all demos.
Public Function RunDemo() As Boolean
Dim ret As Boolean = True
Dim retTmp As Boolean
' Call IsSubsetOf demo.
retTmp = IsSubsetOfDemo()
If retTmp Then
Console.Out.WriteLine("IsSubset demo completed successfully.")
Else
Console.Out.WriteLine("IsSubset demo failed.")
End If
ret = retTmp AndAlso ret
' Call Union demo.
retTmp = UnionDemo()
If retTmp Then
Console.Out.WriteLine("Union demo completed successfully.")
Else
Console.Out.WriteLine("Union demo failed.")
End If
ret = retTmp AndAlso ret
' Call Intersect demo.
retTmp = IntersectDemo()
If retTmp Then
Console.Out.WriteLine("Intersect demo completed successfully.")
Else
Console.Out.WriteLine("Intersect demo failed.")
End If
ret = retTmp AndAlso ret
' Call Copy demo.
retTmp = CopyDemo()
If retTmp Then
Console.Out.WriteLine("Copy demo completed successfully.")
Else
Console.Out.WriteLine("Copy demo failed.")
End If
ret = retTmp AndAlso ret
' Call ToFromXml demo.
retTmp = ToFromXmlDemo()
If retTmp Then
Console.Out.WriteLine("ToFromXml demo completed successfully.")
Else
Console.Out.WriteLine("ToFromXml demo failed.")
End If
ret = retTmp AndAlso ret
' Call SetGetPathList demo.
retTmp = SetGetPathListDemo()
If retTmp Then
Console.Out.WriteLine("SetGetPathList demo completed successfully.")
Else
Console.Out.WriteLine("SetGetPathList demo failed.")
End If
ret = retTmp AndAlso ret
Return ret
End Function 'RunDemo
' Test harness.
Public Shared Sub Main(ByVal args() As String)
Try
Dim democase As New EnvironmentPermissionDemo()
Dim ret As Boolean = democase.RunDemo()
If ret Then
Console.Out.WriteLine("EnvironmentPermission demo completed successfully.")
Console.Out.WriteLine("Press the Enter key to exit.")
Dim consoleInput As String = Console.ReadLine()
System.Environment.ExitCode = 100
Else
Console.Out.WriteLine("EnvironmentPermission demo failed.")
Console.Out.WriteLine("Press the Enter key to exit.")
Dim consoleInput As String = Console.ReadLine()
System.Environment.ExitCode = 101
End If
Catch e As Exception
Console.Out.WriteLine("EnvironmentPermission demo failed.")
Console.WriteLine(e.ToString())
Console.Out.WriteLine("Press the Enter key to exit.")
Dim consoleInput As String = Console.ReadLine()
System.Environment.ExitCode = 101
End Try
End Sub 'Main
End Class 'EnvironmentPermissionDemo
using System;
using System.Security;
using System.Security.Permissions;
using System.Collections;
[assembly: CLSCompliant(true)]
public class EnvironmentPermissionDemo
{
// IsSubsetOf determines whether the current permission is a subset of the specified permission.
private bool IsSubsetOfDemo()
{
bool returnValue = true;
EnvironmentPermission envPerm1 = new EnvironmentPermission(EnvironmentPermissionAccess.Read, "windir");
EnvironmentPermission envPerm2 = new EnvironmentPermission(EnvironmentPermissionAccess.AllAccess, "TEMP");
if (envPerm1.IsSubsetOf(envPerm2))
{
Console.WriteLine("'windir' is a subset of 'TEMP'\n");
}
else
{
Console.WriteLine("windir" + " is not a subset of "
+ "TEMP" + "\n");
}
envPerm1.SetPathList(EnvironmentPermissionAccess.Read, "TEMP");
if (envPerm1.IsSubsetOf(envPerm2))
{
Console.WriteLine("Read access is a subset of AllAccess\n");
}
else
{
Console.WriteLine("Read access is not a subset of AllAccess\n");
}
return returnValue;
}
// Union creates a new permission that is the union of the current permission and the specified permission.
private bool UnionDemo()
{
bool returnValue = true;
IPermission envIdPerm3;
EnvironmentPermission envPerm1 = new EnvironmentPermission(EnvironmentPermissionAccess.Read, "windir");
EnvironmentPermission envPerm2 = new EnvironmentPermission(EnvironmentPermissionAccess.Read, "TEMP");
envIdPerm3 = (EnvironmentPermission)envPerm1.Union(envPerm2);
envIdPerm3 = envPerm1.Union(envPerm2);
Console.WriteLine("The union of 'windir' and 'TEMP'" +
" = " + ((EnvironmentPermission)envIdPerm3).GetPathList(EnvironmentPermissionAccess.Read).ToString());
return returnValue;
}
// Intersect creates and returns a new permission that is the intersection of
// the current permission and the permission specified.
private bool IntersectDemo()
{
IPermission envIdPerm3;
bool returnValue = true;
EnvironmentPermission envPerm1 = new EnvironmentPermission(EnvironmentPermissionAccess.Read, "windir");
EnvironmentPermission envPerm2 = new EnvironmentPermission(EnvironmentPermissionAccess.Read, "TEMP");
try
{
envIdPerm3 = (EnvironmentPermission)envPerm1.Intersect(envPerm2);
if (envIdPerm3 != null && ((EnvironmentPermission)envIdPerm3).GetPathList(EnvironmentPermissionAccess.Read) != null)
{
Console.WriteLine("The intersection of " + "windir" + " and " + "TEMP" + " = " + ((EnvironmentPermission)envIdPerm3).GetPathList(EnvironmentPermissionAccess.Read).ToString());
}
else
{
Console.WriteLine("The intersection of " + "windir" + " and "
+ "TEMP" + " is null.");
}
}
catch (Exception e)
{
Console.WriteLine("An exception was thrown for intersection : " + e);
returnValue = false;
}
return returnValue;
}
//Copy creates and returns an identical copy of the current permission.
private bool CopyDemo()
{
bool returnValue = true;
EnvironmentPermission envPerm1 = new EnvironmentPermission(EnvironmentPermissionAccess.Read, "windir");
try
{
EnvironmentPermission envPerm2 = (EnvironmentPermission)envPerm1.Copy();
if (envPerm2 != null)
{
Console.WriteLine("Result of copy = " + envPerm2.ToString() + "\n");
}
else
{
Console.WriteLine("Result of copy is null. \n");
}
}
catch (Exception e)
{
Console.WriteLine(e);
}
return returnValue;
}
// ToXml creates an XML encoding of the permission and its current state; FromXml reconstructs
// a permission with the specified state from the XML encoding.
private bool ToFromXmlDemo()
{
bool returnValue = true;
EnvironmentPermission envPerm1 = new EnvironmentPermission(EnvironmentPermissionAccess.Read, "windir");
EnvironmentPermission envPerm2 = new EnvironmentPermission(PermissionState.None);
envPerm2.FromXml(envPerm1.ToXml());
Console.WriteLine("Result of ToFromXml = " + envPerm2.ToString() + "\n");
return returnValue;
}
// AddPathList adds access for the specified environment variables to the existing state of the permission.
// SetPathList Sets the specified access to the specified environment variables to the existing state
// of the permission.
// GetPathList gets all environment variables with the specified EnvironmentPermissionAccess.
private bool SetGetPathListDemo()
{
try
{
Console.WriteLine("********************************************************\n");
Console.WriteLine("Creating an EnvironmentPermission with AllAccess rights for 'TMP'");
EnvironmentPermission envPerm1 = new EnvironmentPermission(EnvironmentPermissionAccess.AllAccess, "TMP");
Console.WriteLine("Adding 'TEMP' to the write access list, and 'windir' to the read access list.");
envPerm1.AddPathList(EnvironmentPermissionAccess.Write, "TEMP");
envPerm1.AddPathList(EnvironmentPermissionAccess.Read, "windir");
Console.WriteLine("Read access list before SetPathList = "
+ envPerm1.GetPathList(EnvironmentPermissionAccess.Read));
Console.WriteLine("Setting read access to 'TMP'");
envPerm1.SetPathList(EnvironmentPermissionAccess.Read, "TMP");
Console.WriteLine("Read access list after SetPathList = "
+ envPerm1.GetPathList(EnvironmentPermissionAccess.Read));
Console.WriteLine("Write access list = " + envPerm1.GetPathList(EnvironmentPermissionAccess.Write));
Console.WriteLine("Write access environment variables = "
+ envPerm1.GetPathList(EnvironmentPermissionAccess.AllAccess));
}
catch (ArgumentException e)
{
// EnvironmentPermissionAccess.AllAccess cannot be used as a parameter for GetPathList.
Console.WriteLine("An ArgumentException occurred as a result of using AllAccess. "
+ " This property cannot be used as a parameter in GetPathList, because it represents "
+ "more than one type of environment variable : \n" + e);
}
return true;
}
// Invoke all demos.
public bool RunDemo()
{
bool ret = true;
bool retTmp;
// Call IsSubsetOf demo.
if (retTmp = IsSubsetOfDemo()) Console.Out.WriteLine("IsSubset demo completed successfully.");
else Console.Out.WriteLine("IsSubset demo failed.");
ret = retTmp && ret;
// Call Union demo.
if (retTmp = UnionDemo()) Console.Out.WriteLine("Union demo completed successfully.");
else Console.Out.WriteLine("Union demo failed.");
ret = retTmp && ret;
// Call Intersect demo.
if (retTmp = IntersectDemo()) Console.Out.WriteLine("Intersect demo completed successfully.");
else Console.Out.WriteLine("Intersect demo failed.");
ret = retTmp && ret;
// Call Copy demo.
if (retTmp = CopyDemo()) Console.Out.WriteLine("Copy demo completed successfully.");
else Console.Out.WriteLine("Copy demo failed.");
ret = retTmp && ret;
// Call ToFromXml demo.
if (retTmp = ToFromXmlDemo()) Console.Out.WriteLine("ToFromXml demo completed successfully.");
else Console.Out.WriteLine("ToFromXml demo failed.");
ret = retTmp && ret;
// Call SetGetPathList demo.
if (retTmp = SetGetPathListDemo()) Console.Out.WriteLine("SetGetPathList demo completed successfully.");
else Console.Out.WriteLine("SetGetPathList demo failed.");
ret = retTmp && ret;
return (ret);
}
// Test harness.
public static void Main(String[] args)
{
try
{
EnvironmentPermissionDemo democase = new EnvironmentPermissionDemo();
bool ret = democase.RunDemo();
if (ret)
{
Console.Out.WriteLine("EnvironmentPermission demo completed successfully.");
Console.Out.WriteLine("Press the Enter key to exit.");
string consoleInput = Console.ReadLine();
System.Environment.ExitCode = 100;
}
else
{
Console.Out.WriteLine("EnvironmentPermission demo failed.");
Console.Out.WriteLine("Press the Enter key to exit.");
string consoleInput = Console.ReadLine();
System.Environment.ExitCode = 101;
}
}
catch (Exception e)
{
Console.Out.WriteLine("EnvironmentPermission demo failed.");
Console.WriteLine(e.ToString());
Console.Out.WriteLine("Press the Enter key to exit.");
string consoleInput = Console.ReadLine();
System.Environment.ExitCode = 101;
}
}
}
继承层次结构
System.Object
System.Security.CodeAccessPermission
System.Security.Permissions.EnvironmentPermission
线程安全
此类型的任何公共静态（Visual Basic 中的 Shared）成员都是线程安全的，但不保证所有实例成员都是线程安全的。
平台
Windows 98、Windows 2000 SP4、Windows Millennium Edition、Windows Server 2003、Windows XP Media Center Edition、Windows XP Professional x64 Edition、Windows XP SP2、Windows XP Starter Edition
.NET Framework 并不是对每个平台的所有版本都提供支持。有关受支持版本的列表，请参见系统要求。
版本信息
.NET Framework
受以下版本支持：2.0、1.1、1.0
请参见
参考
EnvironmentPermission 成员
System.Security.Permissions 命名空间
EnvironmentPermissionAttribute
EnvironmentPermissionAccess