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保存自訂物件

只要您建立的自訂物件其屬性只有使用簡單的資料類型，例如 integer 與 string，就不需要為這些自訂物件實作自訂持續性。預設的持續性實作可以儲存物件的中繼資料，及其所有屬性值。

不過，如果您的物件具有使用複雜資料類型的屬性，或是如果您想要在載入和儲存屬性值時，在它們上面執行自訂處理，可以實作 IDTSComponentPersist 介面及其 LoadFromXML 與 SaveToXML 方法。在這些方法中，您從封裝的 XML 定義載入 XML 片段 (或是將它儲存到封裝的 XML 定義)，而 XML 片段包含物件的屬性以及其目前的值。並未定義這個 XML 片段的格式，它必須只能是格式正確的 XML。

重要事項重要事項

當您實作自訂持續性時，必須保存物件的所有屬性，包括繼承的屬性和您加入的自訂屬性。

範例

雖然 Codeplex 網站上的＜Sql Server 自訂連接管理員＞範例並不需要 string 類型之三個屬性的自訂持續性，不過，下列程式碼所顯示的自訂程式碼範例，將需要保存連接管理員及其屬性。包含此程式碼的類別必須實作 IDTSComponentPersist 介面。

  Private Const PERSIST_ELEMENT As String = "SqlConnectionManager"
  Private Const PERSIST_SERVER As String = "Server"
  Private Const PERSIST_DATABASE As String = "Database"
  Private Const PERSIST_CONNECTIONSTRING As String = "ConnectionString"

  Public Sub LoadFromXML(ByVal node As System.Xml.XmlElement, _
    ByVal infoEvents As Microsoft.SqlServer.Dts.Runtime.IDTSInfoEvents) _
    Implements Microsoft.SqlServer.Dts.Runtime.IDTSComponentPersist.LoadFromXML

    Dim propertyNode As XmlNode

    ' Make sure that the correct node is being loaded.
    If node.Name <> PERSIST_ELEMENT Then
      Throw New Exception("Persisted element is not of type " & PERSIST_ELEMENT)
    End If

    ' Load the three properties of the object from XML into variables.
    For Each propertyNode In node.ChildNodes
      Select Case propertyNode.Name
        Case PERSIST_SERVER
          _serverName = propertyNode.InnerText
        Case PERSIST_DATABASE
          _databaseName = propertyNode.InnerText
        Case PERSIST_CONNECTIONSTRING
          _connectionString = propertyNode.InnerText
      End Select
    Next

  End Sub

  Public Sub SaveToXML(ByVal doc As System.Xml.XmlDocument, _
    ByVal infoEvents As Microsoft.SqlServer.Dts.Runtime.IDTSInfoEvents) _
    Implements Microsoft.SqlServer.Dts.Runtime.IDTSComponentPersist.SaveToXML

    Dim elementRoot As XmlElement
    Dim propertyNode As XmlNode

    ' Create a new node to persist the object and its properties.
    elementRoot = doc.CreateElement(String.Empty, PERSIST_ELEMENT, String.Empty)

    ' Save the three properties of the object from variables into XML.
    propertyNode = doc.CreateNode(XmlNodeType.Element, PERSIST_SERVER, String.Empty)
    propertyNode.InnerText = _serverName
    elementRoot.AppendChild(propertyNode)

    propertyNode = doc.CreateNode(XmlNodeType.Element, PERSIST_DATABASE, String.Empty)
    propertyNode.InnerText = _databaseName
    elementRoot.AppendChild(propertyNode)

    propertyNode = doc.CreateNode(XmlNodeType.Element, PERSIST_CONNECTIONSTRING, String.Empty)
    propertyNode.InnerText = _connectionString
    elementRoot.AppendChild(propertyNode)

    doc.AppendChild(elementRoot)

  End Sub

    private const string PERSIST_ELEMENT = "SqlConnectionManager";
    private const string PERSIST_SERVER = "Server";
    private const string PERSIST_DATABASE = "Database";
    private const string PERSIST_CONNECTIONSTRING = "ConnectionString";

    public void LoadFromXML(System.Xml.XmlElement node,
      Microsoft.SqlServer.Dts.Runtime.IDTSInfoEvents infoEvents)
    {

      // Make sure that the correct node is being loaded.
      if (node.Name != PERSIST_ELEMENT)
      {
        throw new Exception("Persisted element is not of type " + PERSIST_ELEMENT);
      }

      // Save the three properties of the object from variables into XML.
      foreach (XmlNode propertyNode in node.ChildNodes)
      {
        switch (propertyNode.Name)
        {
          case PERSIST_SERVER:
            _serverName = propertyNode.InnerText;
            break;
          case PERSIST_DATABASE:
            _databaseName = propertyNode.InnerText;
            break;
          case PERSIST_CONNECTIONSTRING:
            _connectionString = propertyNode.InnerText;
            break;
        }
      }

    }

    public void SaveToXML(System.Xml.XmlDocument doc,
      Microsoft.SqlServer.Dts.Runtime.IDTSInfoEvents infoEvents)
    {

      XmlElement elementRoot;
      XmlNode propertyNode;

      // Create a new node to persist the object and its properties.
      elementRoot = doc.CreateElement(String.Empty, PERSIST_ELEMENT, String.Empty);

      // Save the three properties of the object from variables into XML.
      propertyNode = doc.CreateNode(XmlNodeType.Element, PERSIST_SERVER, String.Empty);
      propertyNode.InnerText = _serverName;
      elementRoot.AppendChild(propertyNode);

      propertyNode = doc.CreateNode(XmlNodeType.Element, PERSIST_DATABASE, String.Empty);
      propertyNode.InnerText = _databaseName;
      elementRoot.AppendChild(propertyNode);

      propertyNode = doc.CreateNode(XmlNodeType.Element, PERSIST_CONNECTIONSTRING, String.Empty);
      propertyNode.InnerText = _connectionString;
      elementRoot.AppendChild(propertyNode);

      doc.AppendChild(elementRoot);

    }
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