XmlValidatingReader.Read Metodo

Definizione

Spazio dei nomi:

System.Xml

Assembly:

System.Xml.ReaderWriter.dll

Assembly:

System.Xml.dll

Assembly:

netstandard.dll

Legge il nodo successivo dal flusso.

public:
 override bool Read();

public override bool Read ();

override this.Read : unit -> bool

Public Overrides Function Read () As Boolean

Restituisce

Boolean

true se è stata completata la lettura del nodo successivo; false se non esistono altri nodi da leggere.

Esempio

Nell'esempio seguente viene letto un file XML e viene visualizzato ogni nodo.

#using <System.Xml.dll>

using namespace System;
using namespace System::IO;
using namespace System::Xml;
int main()
{
   XmlTextReader^ txtreader = nullptr;
   XmlValidatingReader^ reader = nullptr;
   String^ filename = "items.xml";
   try
   {
      
      //Load the reader with the data file and ignore all white space nodes.         
      txtreader = gcnew XmlTextReader( filename );
      txtreader->WhitespaceHandling = WhitespaceHandling::None;
      
      //Implement the validating reader over the text reader. 
      reader = gcnew XmlValidatingReader( txtreader );
      reader->ValidationType = ValidationType::None;
      
      //Parse the file and display each of the nodes.
      while ( reader->Read() )
      {
         switch ( reader->NodeType )
         {
            case XmlNodeType::Element:
               Console::Write( "<{0}>", reader->Name );
               break;

            case XmlNodeType::Text:
               Console::Write( reader->Value );
               break;

            case XmlNodeType::CDATA:
               Console::Write( "<![CDATA[{0}]]>", reader->Value );
               break;

            case XmlNodeType::ProcessingInstruction:
               Console::Write( "<?{0} {1}?>", reader->Name, reader->Value );
               break;

            case XmlNodeType::Comment:
               Console::Write( "<!--{0}-->", reader->Value );
               break;

            case XmlNodeType::XmlDeclaration:
               Console::Write( "<?xml version='1.0'?>" );
               break;

            case XmlNodeType::Document:
               break;

            case XmlNodeType::DocumentType:
               Console::Write( "<!DOCTYPE {0} [{1}]", reader->Name, reader->Value );
               break;

            case XmlNodeType::EntityReference:
               Console::Write( reader->Name );
               break;

            case XmlNodeType::EndElement:
               Console::Write( "</{0}>", reader->Name );
               break;
         }
      }
   }
   finally
   {
      if ( reader != nullptr )
            reader->Close();
   }

}

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

public class Sample
{
  private const String filename = "items.xml";

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

     try
     {
        //Load the reader with the data file and ignore all white space nodes.
        txtreader = new XmlTextReader(filename);
        txtreader.WhitespaceHandling = WhitespaceHandling.None;

        //Implement the validating reader over the text reader.
        reader = new XmlValidatingReader(txtreader);
        reader.ValidationType = ValidationType.None;

        //Parse the file and display each of the nodes.
        while (reader.Read())
        {
           switch (reader.NodeType)
           {
             case XmlNodeType.Element:
               Console.Write("<{0}>", reader.Name);
               break;
             case XmlNodeType.Text:
               Console.Write(reader.Value);
               break;
             case XmlNodeType.CDATA:
               Console.Write("<![CDATA[{0}]]>", reader.Value);
               break;
             case XmlNodeType.ProcessingInstruction:
               Console.Write("<?{0} {1}?>", reader.Name, reader.Value);
               break;
             case XmlNodeType.Comment:
               Console.Write("<!--{0}-->", reader.Value);
               break;
             case XmlNodeType.XmlDeclaration:
               Console.Write("<?xml version='1.0'?>");
               break;
             case XmlNodeType.Document:
               break;
             case XmlNodeType.DocumentType:
               Console.Write("<!DOCTYPE {0} [{1}]", reader.Name, reader.Value);
               break;
             case XmlNodeType.EntityReference:
               Console.Write(reader.Name);
               break;
             case XmlNodeType.EndElement:
               Console.Write("</{0}>", reader.Name);
               break;
           }
        }
     }

     finally
     {
        if (reader!=null)
          reader.Close();
     }
  }
} // End class

Imports System.IO
Imports System.Xml

Public Class Sample
   Private Const filename As String = "items.xml"
   
   Public Shared Sub Main()
      Dim txtreader As XmlTextReader = Nothing
      Dim reader As XmlValidatingReader = Nothing
      
      Try
         'Load the reader with the data file and ignore all white space nodes.         
         txtreader = New XmlTextReader(filename)
         txtreader.WhitespaceHandling = WhitespaceHandling.None
         
         'Implement the validating reader over the text reader. 
         reader = New XmlValidatingReader(txtreader)
         reader.ValidationType = ValidationType.None
         
         'Parse the file and display each of the nodes.
         While reader.Read()
            Select Case reader.NodeType
               Case XmlNodeType.Element
                  Console.Write("<{0}>", reader.Name)
               Case XmlNodeType.Text
                  Console.Write(reader.Value)
               Case XmlNodeType.CDATA
                  Console.Write("<![CDATA[{0}]]>", reader.Value)
               Case XmlNodeType.ProcessingInstruction
                  Console.Write("<?{0} {1}?>", reader.Name, reader.Value)
               Case XmlNodeType.Comment
                  Console.Write("<!--{0}-->", reader.Value)
               Case XmlNodeType.XmlDeclaration
                  Console.Write("<?xml version='1.0'?>")
               Case XmlNodeType.Document
               Case XmlNodeType.DocumentType
                  Console.Write("<!DOCTYPE {0} [{1}]", reader.Name, reader.Value)
               Case XmlNodeType.EntityReference
                  Console.Write(reader.Name)
               Case XmlNodeType.EndElement
                  Console.Write("</{0}>", reader.Name)
            End Select
         End While
      
      Finally
         If Not (reader Is Nothing) Then
            reader.Close()
         End If
      End Try
   End Sub
End Class

Nell'esempio viene usato il file, , items.xmlcome input.

<?xml version="1.0"?>
<!-- This is a sample XML document -->
<!DOCTYPE Items [<!ENTITY number "123">]>
<Items>
  <Item>Test with an entity: &number;</Item>
  <Item>test with a child element <more/> stuff</Item>
  <Item>test with a CDATA section <![CDATA[<456>]]> def</Item>
  <Item>Test with a char entity: &#65;</Item>
  <!-- Fourteen chars in this element.-->
  <Item>1234567890ABCD</Item>
</Items>

Commenti

Nota

La XmlValidatingReader classe è obsoleta in .NET Framework 2.0. È possibile creare un'istanza di convalida XmlReader usando la classe e il Create XmlReaderSettings metodo . Per altre informazioni, vedere la sezione Note della pagina di riferimento XmlReader.

Quando un lettore viene creato e inizializzato, non sono disponibili informazioni. È necessario chiamare Read per leggere il primo nodo.

Vedi anche

• XmlReader