FileRegion.GetStream Método

Definición

Espacio de nombres:

System.IO.Log

Ensamblado:

System.IO.Log.dll

Devuelve una secuencia que se puede utilizar para leer los datos que se van a estar almacenado.

public:
 System::IO::Stream ^ GetStream();

public System.IO.Stream GetStream ();

member this.GetStream : unit -> System.IO.Stream

Public Function GetStream () As Stream

Devoluciones

Stream

Una secuencia que contiene los datos que se van a almacenar.

Excepciones

IOException

La solicitud no se pudo realizar debido a una excepción de E/S inesperada.

NotSupportedException

La operación no es compatible.

ObjectDisposedException

Se llamó al método una vez eliminada la secuencia.

OutOfMemoryException

No hay bastante memoria para continuar la ejecución del programa.

UnauthorizedAccessException

El acceso al almacén del registro especificado ha sido denegado por el sistema operativo.

Ejemplos

El ejemplo siguiente muestra cómo archivar un almacén del registro en XML utilizando LogStore y las clases FileRegion.

class LogBackup
{
    static void ArchiveToXML(LogStore logStore, string fileName)
    {

        LogArchiveSnapshot snapshot = logStore.CreateLogArchiveSnapshot();
        {
            XmlTextWriter writer = new XmlTextWriter(fileName, System.Text.Encoding.ASCII);
            writer.WriteStartElement("logArchive");

            foreach (FileRegion region in snapshot.ArchiveRegions)
            {
                writer.WriteStartElement("fileRegion");
                writer.WriteElementString("path",
                                          region.Path);
                writer.WriteElementString("length",
                                        region.FileLength.ToString());
                writer.WriteElementString("offset",
                                          region.Offset.ToString());

                using (Stream dataStream = region.GetStream())
                {
                    byte[] data = new byte[dataStream.Length];
                    dataStream.Read(data, 0, data.Length);

                    writer.WriteElementString("data", System.Convert.ToBase64String(data));
                }

                writer.WriteEndElement();
            }

            writer.Close();
            logStore.SetArchiveTail(snapshot.LastSequenceNumber);
        }
    }

    static void RestoreFromXML(string fileName)
    {
        using (XmlTextReader reader = new XmlTextReader(fileName))
        {
            reader.ReadStartElement("logArchive");
            while (reader.IsStartElement())
            {
                string path;
                long length;
                long offset;
                path = reader.ReadElementString("path");
                length = System.Int64.Parse(reader.ReadElementString("length"));
                offset = System.Int64.Parse(reader.ReadElementString("offset"));
                string dataString = reader.ReadElementString("data");
                byte[] data = System.Convert.FromBase64String(dataString);
                FileStream fileStream;
                using (fileStream = new FileStream(path,
                                              FileMode.OpenOrCreate,
                                              FileAccess.Write))
                {
                    fileStream.SetLength(length);
                    fileStream.Position = offset;
                    fileStream.Write(data, 0, data.Length);
                }
            }
            reader.ReadEndElement();
        }
    }
}

Friend Class LogBackup
    Private Shared Sub ArchiveToXML(ByVal logStore As LogStore, ByVal fileName As String)


        Dim snapshot As LogArchiveSnapshot = logStore.CreateLogArchiveSnapshot()
            Dim writer As New XmlTextWriter(fileName, System.Text.Encoding.ASCII)
            writer.WriteStartElement("logArchive")

        For Each region As FileRegion In snapshot.ArchiveRegions
            With writer
                .WriteStartElement("fileRegion")
                .WriteElementString("path", region.Path)
                .WriteElementString("length", region.FileLength.ToString())
                .WriteElementString("offset", region.Offset.ToString())
            End With

            Using dataStream As Stream = region.GetStream()
                Dim data(dataStream.Length - 1) As Byte
                dataStream.Read(data, 0, data.Length)

                writer.WriteElementString("data", System.Convert.ToBase64String(data))
            End Using

            writer.WriteEndElement()
        Next region

            writer.Close()
            logStore.SetArchiveTail(snapshot.LastSequenceNumber)
    End Sub

    Private Shared Sub RestoreFromXML(ByVal fileName As String)
        Using reader As New XmlTextReader(fileName)
            reader.ReadStartElement("logArchive")
            Do While reader.IsStartElement()
                Dim path As String
                Dim length As Long
                Dim offset As Long
                path = reader.ReadElementString("path")
                length = System.Int64.Parse(reader.ReadElementString("length"))
                offset = System.Int64.Parse(reader.ReadElementString("offset"))
                Dim dataString = reader.ReadElementString("data")
                Dim data() = System.Convert.FromBase64String(dataString)
                Dim fileStream As FileStream
                fileStream = New FileStream(path, FileMode.OpenOrCreate, FileAccess.Write)
                Using fileStream
                    fileStream.SetLength(length)
                    fileStream.Position = offset
                    fileStream.Write(data, 0, data.Length)
                End Using
            Loop
            reader.ReadEndElement()
        End Using
    End Sub
End Class