XmlValidatingReader.ResolveEntity 方法

定義

命名空間:

System.Xml

組件:

System.Xml.ReaderWriter.dll

組件:

System.Xml.dll

組件:

netstandard.dll

解析 EntityReference 節點的實體參考。

public:
 override void ResolveEntity();

public override void ResolveEntity ();

override this.ResolveEntity : unit -> unit

Public Overrides Sub ResolveEntity ()

例外狀況

InvalidOperationException

讀取器不在 EntityReference 節點上。

範例

下列範例會使用 ResolveEntity 展開一般實體。

#using <System.Xml.dll>

using namespace System;
using namespace System::IO;
using namespace System::Xml;
int main()
{
   XmlValidatingReader^ reader = nullptr;
   XmlTextReader^ txtreader = nullptr;
   try
   {
      
      //Create and load the XmlTextReader with the XML file. 
      txtreader = gcnew XmlTextReader( "book1.xml" );
      txtreader->WhitespaceHandling = WhitespaceHandling::None;
      
      //Create the XmlValidatingReader over the XmlTextReader.
      //Set the reader to not expand general entities.
      reader = gcnew XmlValidatingReader( txtreader );
      reader->ValidationType = ValidationType::None;
      reader->EntityHandling = EntityHandling::ExpandCharEntities;
      reader->MoveToContent(); //Move to the root element.
      reader->Read(); //Move to title start tag.
      reader->Skip(); //Skip the title element.
      
      //Read the misc start tag.  The reader is now positioned on
      //the entity reference node.
      reader->ReadStartElement();
      
      //Because EntityHandling is set to ExpandCharEntities, you must call 
      //ResolveEntity to expand the entity.  The entity replacement text is 
      //then parsed and returned as a child node.         
      Console::WriteLine( "Expand the entity..." );
      reader->ResolveEntity();
      Console::WriteLine( "The entity replacement text is returned as a text node." );
      reader->Read();
      Console::WriteLine( "NodeType: {0} Value: {1}", reader->NodeType, reader->Value );
      Console::WriteLine( "An EndEntity node closes the entity reference scope." );
      reader->Read();
      Console::WriteLine( "NodeType: {0} Name: {1}", reader->NodeType, reader->Name );
   }
   finally
   {
      if ( reader != nullptr )
            reader->Close();
   }

}

using System;
using System.IO;
using System.Xml;

public class Sample
{
  public static void Main()
  {
     XmlValidatingReader reader = null;
     XmlTextReader txtreader = null;

     try
     {
       //Create and load the XmlTextReader with the XML file.
       txtreader = new XmlTextReader("book1.xml");
       txtreader.WhitespaceHandling = WhitespaceHandling.None;

       //Create the XmlValidatingReader over the XmlTextReader.
       //Set the reader to not expand general entities.
       reader = new XmlValidatingReader(txtreader);
       reader.ValidationType = ValidationType.None;
       reader.EntityHandling = EntityHandling.ExpandCharEntities;

       reader.MoveToContent();  //Move to the root element.
       reader.Read();  //Move to title start tag.
       reader.Skip();  //Skip the title element.

       //Read the misc start tag.  The reader is now positioned on
       //the entity reference node.
       reader.ReadStartElement();

       //Because EntityHandling is set to ExpandCharEntities, you must call
       //ResolveEntity to expand the entity.  The entity replacement text is
       //then parsed and returned as a child node.
       Console.WriteLine("Expand the entity...");
       reader.ResolveEntity();

       Console.WriteLine("The entity replacement text is returned as a text node.");
       reader.Read();
       Console.WriteLine("NodeType: {0} Value: {1}", reader.NodeType ,reader.Value);

       Console.WriteLine("An EndEntity node closes the entity reference scope.");
       reader.Read();
       Console.WriteLine("NodeType: {0} Name: {1}", reader.NodeType,reader.Name);
    }
    finally
    {
       if (reader != null)
         reader.Close();
    }
  }
}

Option Strict
Option Explicit

Imports System.IO
Imports System.Xml

Public Class Sample
   
   Public Shared Sub Main()
      Dim reader As XmlValidatingReader = Nothing
      Dim txtreader As XmlTextReader = Nothing
      
      Try
         'Create and load the XmlTextReader with the XML file. 
         txtreader = New XmlTextReader("book1.xml")
         txtreader.WhitespaceHandling = WhitespaceHandling.None
         
         'Create the XmlValidatingReader over the XmlTextReader.
         'Set the reader to not expand general entities.
         reader = New XmlValidatingReader(txtreader)
         reader.ValidationType = ValidationType.None
         reader.EntityHandling = EntityHandling.ExpandCharEntities
         
         reader.MoveToContent() 'Move to the root element.
         reader.Read() 'Move to title start tag.
         reader.Skip() 'Skip the title element.
         'Read the misc start tag.  The reader is now positioned on
         'the entity reference node.
         reader.ReadStartElement()
         
         'Because EntityHandling is set to ExpandCharEntities, you must call 
         'ResolveEntity to expand the entity.  The entity replacement text is 
         'then parsed and returned as a child node.  
         Console.WriteLine("Expand the entity...")
         reader.ResolveEntity()
         
         Console.WriteLine("The entity replacement text is returned as a text node.")
         reader.Read()
         Console.WriteLine("NodeType: {0} Value: {1}", reader.NodeType, reader.Value)
         
         Console.WriteLine("An EndEntity node closes the entity reference scope.")
         reader.Read()
         Console.WriteLine("NodeType: {0} Name: {1}", reader.NodeType, reader.Name)
      
      Finally
         If Not (reader Is Nothing) Then
            reader.Close()
         End If
      End Try
   End Sub
End Class

此範例會使用 檔案 book1.xml ，作為輸入。

<?xml version='1.0' ?>
<!DOCTYPE book [<!ENTITY h 'hardcover'>]>
<book>
  <title>Pride And Prejudice</title>
  <misc>&h;</misc>
</book>

備註

注意

類別 XmlValidatingReader 在 .NET Framework 2.0 中已過時。 您可以使用 類別和 Create 方法建立驗證 XmlReader 實例 XmlReaderSettings 。 如需詳細資訊，請參閱 XmlReader 參考頁面的＜備註＞一節。

如果讀取器位於 EntityReference 節點 () XmlNodeType.EntityReference ，如果在 Read 呼叫此方法之後呼叫 ，則會剖析實體取代文字。 實體取代文字完成之後， EndEntity 會傳回節點以關閉實體參考範圍。

注意

呼叫此方法之後，如果實體是屬性值的一部分，您必須呼叫 以逐步執行 ReadAttributeValue 實體。

另請參閱

• EntityHandling
• XmlReader