XmlTextReader.Read Método

Definição

Lê o próximo nó do fluxo.Reads the next node from the stream.

public:
 override bool Read();
public override bool Read ();
override this.Read : unit -> bool
Public Overrides Function Read () As Boolean

Retornos

Boolean

true se o próximo nó for lido com êxito; false se não houver mais nenhum nó para ler.true if the next node was read successfully; false if there are no more nodes to read.

Exceções

Erro ao analisar o XML.An error occurred while parsing the XML.

Exemplos

O exemplo a seguir lê um arquivo XML e exibe cada nó.The following example reads an XML file and displays each node.

#using <System.Xml.dll>

using namespace System;
using namespace System::IO;
using namespace System::Xml;
int main()
{
   XmlTextReader^ reader = nullptr;
   String^ filename = "items.xml";
   try
   {
      
      // Load the reader with the data file and ignore all white space nodes.         
      reader = gcnew XmlTextReader( filename );
      reader->WhitespaceHandling = WhitespaceHandling::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 reader = null;

     try {

        // Load the reader with the data file and ignore all white space nodes.
        reader = new XmlTextReader(filename);
        reader.WhitespaceHandling = WhitespaceHandling.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
Option Strict
Option Explicit

Imports System.IO
Imports System.Xml

'Reads an XML document
Public Class Sample
    Private Const filename As String = "items.xml"
    
    Public Shared Sub Main()
        Dim reader As XmlTextReader = Nothing
        
        Try
            ' Load the reader with the data file and ignore all white space nodes.         
            reader = New XmlTextReader(filename)
            reader.WhitespaceHandling = WhitespaceHandling.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

O exemplo usa o arquivo items.xml .The sample uses the file items.xml.


<?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 an char entity: &#65;</Item>
  <!-- Fourteen chars in this element.-->
  <Item>1234567890ABCD</Item>
</Items>

Comentários

Observação

A partir do .NET Framework 2,0, recomendamos que você crie XmlReader instâncias usando o XmlReader.Create método para aproveitar a nova funcionalidade.Starting with the .NET Framework 2.0, we recommend that you create XmlReader instances by using the XmlReader.Create method to take advantage of new functionality.

Quando um leitor é criado e inicializado pela primeira vez, não há informações disponíveis.When a reader is first created and initialized, there is no information available. Você deve chamar Read para ler o primeiro nó.You must call Read to read the first node.

Esse método requer pelo menos quatro bytes do fluxo de dados para começar a análise.This method requires at least four bytes from the data stream in order to begin parsing. Se menos de quatro bytes forem retornados e não houver mais dados no fluxo, o método falhará.If fewer than four bytes are returned and there is no more data in the stream, the method will fail. Se houver mais dados no fluxo, o método bloqueará a análise até o recebimento do quarto byte.If there is more data in the stream, the method will block parsing until receipt of the fourth byte.

Aplica-se a

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