CodeAccessPermission.IsSubsetOf(IPermission) 方法

定义

命名空间:

System.Security

程序集:

System.Security.Permissions.dll

程序集:

mscorlib.dll

通过派生类实现时，确定当前权限是否为指定权限的子集。

public:
 abstract bool IsSubsetOf(System::Security::IPermission ^ target);

public abstract bool IsSubsetOf (System.Security.IPermission target);

abstract member IsSubsetOf : System.Security.IPermission -> bool

Public MustOverride Function IsSubsetOf (target As IPermission) As Boolean

参数

target

IPermission

将要测试子集关系的权限。 此权限必须与当前权限属于同一类型。

返回

Boolean

如果当前权限是指定权限的子集，则为 true；否则为 false。

实现

IsSubsetOf(IPermission)

例外

ArgumentException

target 参数不为 null，并且与当前权限不属于同一类型。

示例

下面的代码示例演示方法 IsSubsetOf 的替代。 此代码示例是为类提供的大型示例的 CodeAccessPermission 一部分。

public:
   virtual bool IsSubsetOf( IPermission^ target ) override
   {
#if ( debug ) 
      Console::WriteLine( "************* Entering IsSubsetOf *********************" );
#endif

      if ( target == nullptr )
      {
         Console::WriteLine( "IsSubsetOf: target == null" );
         return false;
      }

#if ( debug ) 
      Console::WriteLine( "This is = {0}", ((NameIdPermission)this).Name );
      Console::WriteLine( "Target is {0}", ((NameIdPermission)target).m_Name );
#endif

      try
      {
         NameIdPermission^ operand = dynamic_cast<NameIdPermission^>(target);
         
         // The following check for unrestricted permission is only included as an example for
         // permissions that allow the unrestricted state. It is of no value for this permission.
         if ( true == operand->m_Unrestricted )
         {
            return true;
         }
         else if ( true == this->m_Unrestricted )
         {
            return false;
         }

         if ( this->m_Name != nullptr )
         {
            if ( operand->m_Name == nullptr )
            {
               return false;
            }
            if ( this->m_Name->Equals( "" ) )
            {
               return true;
            }
         }

         if ( this->m_Name->Equals( operand->m_Name ) )
         {
            return true;
         }
         else
         {
            // Check for wild card character '*'.
            int i = operand->m_Name->LastIndexOf( "*" );

            if ( i > 0 )
            {
               String^ prefix = operand->m_Name->Substring( 0, i );
               if ( this->m_Name->StartsWith( prefix ) )
               {
                  return true;
               }
            }
         }
         return false;
      }
      catch ( InvalidCastException^ ) 
      {
         throw gcnew ArgumentException( String::Format( "Argument_WrongType", this->GetType()->FullName ) );
      }
   }

        public override bool IsSubsetOf(IPermission target)
        {
#if(debug)
            Console.WriteLine ("************* Entering IsSubsetOf *********************");
#endif
            if (target == null)
            {
                Console.WriteLine ("IsSubsetOf: target == null");
                return false;
            }
#if(debug)

            Console.WriteLine ("This is = " + (( NameIdPermission)this).Name);
            Console.WriteLine ("Target is " + (( NameIdPermission)target).m_Name);
#endif
            try
            {
                 NameIdPermission operand = ( NameIdPermission)target;

                // The following check for unrestricted permission is only included as an example for
                // permissions that allow the unrestricted state. It is of no value for this permission.
                if (true == operand.m_Unrestricted)
                {
                    return true;
                }
                else if (true == this.m_Unrestricted)
                {
                    return false;
                }

                if (this.m_Name != null)
                {
                    if (operand.m_Name == null) return false;

                    if (this.m_Name == "") return true;
                }

                if (this.m_Name.Equals (operand.m_Name))
                {
                    return true;
                }
                else
                {
                    // Check for wild card character '*'.
                    int i = operand.m_Name.LastIndexOf ("*");

                    if (i > 0)
                    {
                        string prefix = operand.m_Name.Substring (0, i);

                        if (this.m_Name.StartsWith (prefix))
                        {
                            return true;
                        }
                    }
                }

                return false;
            }
            catch (InvalidCastException)
            {
                throw new ArgumentException (String.Format ("Argument_WrongType", this.GetType ().FullName));
            }
        }

        Public Overrides Function IsSubsetOf(ByVal target As IPermission) As Boolean

#If (Debug) Then

            Console.WriteLine("************* Entering IsSubsetOf *********************")
#End If
            If target Is Nothing Then
                Console.WriteLine("IsSubsetOf: target == null")
                Return False
            End If
#If (Debug) Then
            Console.WriteLine(("This is = " + CType(Me, NameIdPermission).Name))
            Console.WriteLine(("Target is " + CType(target, NameIdPermission).m_name))
#End If
            Try
                Dim operand As NameIdPermission = CType(target, NameIdPermission)

                ' The following check for unrestricted permission is only included as an example for
                ' permissions that allow the unrestricted state. It is of no value for this permission.
                If True = operand.m_Unrestricted Then
                    Return True
                ElseIf True = Me.m_Unrestricted Then
                    Return False
                End If

                If Not (Me.m_name Is Nothing) Then
                    If operand.m_name Is Nothing Then
                        Return False
                    End If
                    If Me.m_name = "" Then
                        Return True
                    End If
                End If
                If Me.m_name.Equals(operand.m_name) Then
                    Return True
                Else
                    ' Check for wild card character '*'.
                    Dim i As Integer = operand.m_name.LastIndexOf("*")

                    If i > 0 Then
                        Dim prefix As String = operand.m_name.Substring(0, i)

                        If Me.m_name.StartsWith(prefix) Then
                            Return True
                        End If
                    End If
                End If

                Return False
            Catch
                Throw New ArgumentException(String.Format("Argument_WrongType", Me.GetType().FullName))
            End Try
        End Function

注解

如果当前权限指定由指定权限完全包含的操作集，则当前权限是指定权限的子集。 例如，表示对C:\example.txt的访问权限的权限是表示对 C：\ 的访问权限的子集。 如果此方法返回 true，则当前权限表示对受保护资源的访问权限不超过指定的权限。

对于该方法的所有重写IsSubsetOf，需要true以下语句。 X、Y 和 Z 表示非空引用的自定义代码访问权限对象，U 表示不受限制的代码访问权限，N 表示具有以下None项PermissionState的空权限。

• X.IsSubsetOf (X) 返回 true。

• X.IsSubsetOf (Y) 返回与 Y 相同的值。IsSubsetOf (X) ，前提是 X 和 Y 表示同一组权限。

• 如果 为 X。IsSubsetOf (Y) 和 Y。IsSubsetOf (Z) 返回 trueX。IsSubsetOf (Z) 返回 true。

• X.IsSubsetOf (U) 返回 true。

• X.IsSubsetOf (N) 返回 false。

• N.IsSubsetOf (X) 返回 true。

如果 X 和 Y 表示空引用的自定义代码访问权限对象， 则为 X。IsSubsetOf (Y) 返回 true。 如果 Z 也为 null，则复合集运算 X。联合 (Y) 。IsSubsetOf (Z) 也返回 true ，因为两个 null 权限的联合是 null 权限。

实施者说明

必须在派生类中重写此方法。