IHierarchyData.Item 属性

定义

命名空间:

System.Web.UI

程序集:

System.Web.dll

获取 IHierarchyData 对象所表示的分层数据节点。

public:
 property System::Object ^ Item { System::Object ^ get(); };

public object Item { get; }

member this.Item : obj

Public ReadOnly Property Item As Object

属性值

Object

一个 Object 分层数据节点对象。

示例

下面的代码示例演示如何访问IHierarchyData属性、使用Type属性检查对象的类型，以及强制转换对象以执行更多特定于类型的IHierarchyData操作。 此代码示例是为接口提供的大型示例的 IHierarchyData 一部分。

// Print out the current data node, then iterate through its
// children and do the same.
private void PrintFullChildNodeInfo(IHierarchyData node)
{
    string whitespace = "     ";
    string br = "<BR>";

    Response.Write(node.ToString() + br);
    Response.Write(whitespace + node.Path + br);

    // Check for specific types and perform extended functions.
    if (node.Type == "SiteMapNode")
    {
        // Because SiteMapNode implements the IHierarchyData interface,
        // the IHierarchyData object can be cast directly as a SiteMapNode,
        // rather than accessing the Item property for the object that
        // the Type property identifies.
        SiteMapNode siteNode = node.Item as SiteMapNode;
        Response.Write(whitespace + siteNode.Url + br);
        Response.Write(whitespace + siteNode.Description + br);
    }
    else if (node.Type == "SomeBusinessObject")
    {
        // If the IHierarchyData instance is a wrapper class on a business
        // object of some kind, you can retrieve the business object by using
        // the IHierarchyData.Item property.
        //          SomeBusinessObject busObj = node.Item as SomeBusinessObject;
    }

    if (node.HasChildren)
    {
        IEnumerator children = ((IHierarchicalEnumerable)node.GetChildren()).GetEnumerator();

        while (children.MoveNext())
        {
            // Print out SiteMapNode Titles recursively.
            IHierarchyData hierarchicalNode = node.GetChildren().GetHierarchyData(children.Current);
            PrintFullChildNodeInfo(hierarchicalNode);
        }
    }
}

' Print out the current data node, then iterate through its
' children and do the same.

Private Sub PrintFullChildNodeInfo(ByVal node As IHierarchyData)
    Dim whitespace As String = "     "
    Dim br As String = "<BR>"

    Response.Write(Convert.ToString(node) & br)
    Response.Write(whitespace & node.Path & br)

    ' Check for specific types and perform extended functions.
    If node.Type = "SiteMapNode" Then
        ' Because SiteMapNode implements the IHierarchyData interface,
        ' the IHierarchyData object can be cast directly as a SiteMapNode,
        ' rather than accessing the Item property for the object that
        ' the Type property identifies.
        Dim siteNode As SiteMapNode = CType(node.Item, SiteMapNode)
        Response.Write(whitespace & siteNode.Url & br)
        Response.Write(whitespace & siteNode.Description & br)

    ElseIf node.Type = "SomeBusinessObject Then" Then
        ' If the IHierarchyData instance is a wrapper class on a business
        ' object of some kind, you can retrieve the business object by using
        ' the IHierarchyData.Item property.
        '          SomeBusinessObject busObj = node.Item as SomeBusinessObject;
    End If

    If node.HasChildren Then
        Dim children As IEnumerator = CType(node.GetChildren().GetEnumerator(), IHierarchicalEnumerable)
        While children.MoveNext()
            ' Print out SiteMapNode Titles recursively.
            Dim hierarchicalNode As IHierarchyData = node.GetChildren().GetHierarchyData(children.Current)
            PrintFullChildNodeInfo(hierarchicalNode)
        End While
    End If
End Sub

注解

虽然许多表示分层数据节点的类（如 SiteMapNode 类）直接实现 IHierarchyData 接口，但其他类仅充当不实现接口的类的包装器。 当业务对象在功能上等同于对象IHierarchyData但不能轻易重新设计时，会Item针对这些设计情况提供该属性。

另请参阅

• Type