DnsPermission.FromXml(SecurityElement) 方法

定义

以 XML 编码重新构造 DnsPermission 实例。Reconstructs a DnsPermission instance from an XML encoding.

public:
 override void FromXml(System::Security::SecurityElement ^ securityElement);
public override void FromXml (System.Security.SecurityElement securityElement);
override this.FromXml : System.Security.SecurityElement -> unit
Public Overrides Sub FromXml (securityElement As SecurityElement)

参数

securityElement
SecurityElement

用于重新构造 DnsPermission 实例的 XML 编码。The XML encoding to use to reconstruct the DnsPermission instance.

例外

securityElementnullsecurityElement is null.

securityElement 不是一个 DnsPermission 元素。securityElement is not a DnsPermission element.

示例

下面的示例 DnsPermission 从 XML 编码重新构造一个实例。The following example reconstructs a DnsPermission instance from an XML encoding.

public:
   void ConstructDnsPermission()
   {
      try
      {
         // Create a DnsPermission instance.
         DnsPermission^ permission = gcnew DnsPermission( PermissionState::None );
         // Create a SecurityElement instance by calling the ToXml method on the
         // DnsPermission instance.
         // Print its attributes, which hold the  XML encoding of the DnsPermission
         // instance.
         Console::WriteLine( "Attributes and Values of 'DnsPermission' instance :" );
         PrintKeysAndValues( permission->ToXml()->Attributes );
         
         // Create a SecurityElement instance.
         SecurityElement^ securityElementObj = gcnew SecurityElement( "IPermission" );
         // Add attributes and values of the SecurityElement instance corresponding to
         // the permission instance.
         securityElementObj->AddAttribute( "version", "1" );
         securityElementObj->AddAttribute( "Unrestricted", "true" );
         securityElementObj->AddAttribute( "class", "System.Net.DnsPermission" );
         
         // Reconstruct a DnsPermission instance from an XML encoding.
         DnsPermission^ permission1 = gcnew DnsPermission( PermissionState::None );
         permission1->FromXml( securityElementObj );
         
         // Print the attributes and values of the constructed DnsPermission Object*.
         Console::WriteLine( "After reconstruction Attributes and Values of new DnsPermission instance :" );
         PrintKeysAndValues( permission1->ToXml()->Attributes );
      }
      catch ( NullReferenceException^ e ) 
      {
         Console::WriteLine( "NullReferenceException caught!!!" );
         Console::WriteLine( "Source : {0}", e->Source );
         Console::WriteLine( "Message : {0}", e->Message );
      }
      catch ( SecurityException^ e ) 
      {
         Console::WriteLine( "SecurityException caught!!!" );
         Console::WriteLine( "Source : {0}", e->Source );
         Console::WriteLine( "Message : {0}", e->Message );
      }
      catch ( ArgumentNullException^ e ) 
      {
         Console::WriteLine( "ArgumentNullException caught!!!" );
         Console::WriteLine( "Source : {0}", e->Source );
         Console::WriteLine( "Message : {0}", e->Message );
      }
      catch ( Exception^ e ) 
      {
         Console::WriteLine( "Exception caught!!!" );
         Console::WriteLine( "Source : {0}", e->Source );
         Console::WriteLine( "Message : {0}", e->Message );
      }
   }

private:
   void PrintKeysAndValues( Hashtable^ myList )
   {
      // Get the enumerator that can iterate through the hash table.
      IDictionaryEnumerator^ myEnumerator = myList->GetEnumerator();
      Console::WriteLine( "\t-KEY-\t-VALUE-" );
      while ( myEnumerator->MoveNext() )
      {
         Console::WriteLine( "\t {0}:\t {1}", myEnumerator->Key, myEnumerator->Value );
      }
      Console::WriteLine();
   }
public void ConstructDnsPermission() {
  try
  {
    // Create a DnsPermission instance.
    DnsPermission permission = new DnsPermission(PermissionState.None);
    // Create a SecurityElement instance by calling the ToXml method on the
    // DnsPermission instance.
    // Print its attributes, which hold the  XML encoding of the DnsPermission
    // instance.
    Console.WriteLine("Attributes and Values of 'DnsPermission' instance :");
    PrintKeysAndValues(permission.ToXml().Attributes);

    // Create a SecurityElement instance.
    SecurityElement securityElementObj = new SecurityElement("IPermission");
    // Add attributes and values of the SecurityElement instance corresponding to
    // the permission instance.
    securityElementObj.AddAttribute("version", "1");
    securityElementObj.AddAttribute("Unrestricted", "true");
    securityElementObj.AddAttribute("class","System.Net.DnsPermission");

    // Reconstruct a DnsPermission instance from an XML encoding.
      DnsPermission permission1 = new DnsPermission(PermissionState.None);
    permission1.FromXml(securityElementObj);

    // Print the attributes and values of the constructed DnsPermission object.
    Console.WriteLine("After reconstruction Attributes and Values of new DnsPermission instance :");
    PrintKeysAndValues(permission1.ToXml().Attributes);
  }
  catch(NullReferenceException e)
  {
    Console.WriteLine("NullReferenceException caught!!!");
    Console.WriteLine("Source : " + e.Source);
    Console.WriteLine("Message : " + e.Message);
  }
  catch(SecurityException e)
  {
    Console.WriteLine("SecurityException caught!!!");
    Console.WriteLine("Source : " + e.Source);
    Console.WriteLine("Message : " + e.Message);
  }
  catch(ArgumentNullException e)
  {
    Console.WriteLine("ArgumentNullException caught!!!");
    Console.WriteLine("Source : " + e.Source);
    Console.WriteLine("Message : " + e.Message);
  }
  catch(Exception e)
  {
    Console.WriteLine("Exception caught!!!");
    Console.WriteLine("Source : " + e.Source);
    Console.WriteLine("Message : " + e.Message);
  }
}

private void PrintKeysAndValues(Hashtable myList) {
   // Get the enumerator that can iterate through the hash table.
   IDictionaryEnumerator myEnumerator = myList.GetEnumerator();
   Console.WriteLine("\t-KEY-\t-VALUE-");
   while (myEnumerator.MoveNext())
      Console.WriteLine("\t{0}:\t{1}", myEnumerator.Key, myEnumerator.Value);
      Console.WriteLine();
}
Public Sub ConstructDnsPermission()
    Try
        ' Create a DnsPermission instance.
        Dim permission As New DnsPermission(PermissionState.None)
        ' Create a SecurityElement instance by calling the ToXml method on the
        ' DnsPermission instance and print its attributes, 
        ' which hold the  XML encoding of the DnsPermission instance.
        Console.WriteLine("Attributes and Values of 'DnsPermission' instance :")
        PrintKeysAndValues(permission.ToXml().Attributes)
        
        ' Create a SecurityElement instacnce .
        Dim securityElementObj As New SecurityElement("IPermission")
        ' Add attributes and values of the SecurityElement instance corresponding to
        ' the permission instance.
        securityElementObj.AddAttribute("version", "1")
        securityElementObj.AddAttribute("Unrestricted", "true")
        securityElementObj.AddAttribute("class", "System.Net.DnsPermission")
        
        ' Reconstruct a DnsPermission instance from an XML encoding.
        Dim permission1 As New DnsPermission(PermissionState.None)
        permission1.FromXml(securityElementObj)
        
        ' Print the attributes and values of the constructed DnsPermission object.
        Console.WriteLine("After reconstruction Attributes and Values of new DnsPermission instance :")
        PrintKeysAndValues(permission1.ToXml().Attributes)
    Catch e As NullReferenceException
        Console.WriteLine("NullReferenceException caught!!!")
        Console.WriteLine(("Source : " + e.Source))
        Console.WriteLine(("Message : " + e.Message))
    Catch e As SecurityException
        Console.WriteLine("SecurityException caught!!!")
        Console.WriteLine(("Source : " + e.Source))
        Console.WriteLine(("Message : " + e.Message))
    Catch e As ArgumentNullException
        Console.WriteLine("ArgumentNullException caught!!!")
        Console.WriteLine(("Source : " + e.Source))
        Console.WriteLine(("Message : " + e.Message))
    Catch e As Exception
        Console.WriteLine("Exception caught!!!")
        Console.WriteLine(("Source : " + e.Source))
        Console.WriteLine(("Message : " + e.Message))
    End Try
End Sub


Private Sub PrintKeysAndValues(myList As Hashtable)
    ' Get the enumerator that can iterate through the hash table.
    Dim myEnumerator As IDictionaryEnumerator = myList.GetEnumerator()
    Console.WriteLine(ControlChars.Tab + "-KEY-" + ControlChars.Tab + "-VALUE-")
    While myEnumerator.MoveNext()
        Console.WriteLine(ControlChars.Tab + "{0}:" + ControlChars.Tab + "{1}", myEnumerator.Key, myEnumerator.Value)
    End While
    Console.WriteLine()
End Sub

注解

FromXml方法使用 DnsPermission 由类定义的 XML 编码重新构造实例 SecurityElementThe FromXml method reconstructs a DnsPermission instance from an XML encoding defined by the SecurityElement class.

使用 ToXml 方法对实例进行 XML 编码 DnsPermission ,包括状态信息。Use the ToXml method to XML-encode the DnsPermission instance, including state information.

适用于

另请参阅