克隆与附加

更新：November 2007

在将 XNode（包括 XElement）或 XAttribute 对象添加到新树中时，如果新内容没有父级，则直接将这些对象附加到 XML 树中。如果新内容已经有父级，并且是另一 XML 树的一部分，则克隆新内容。然后将新克隆的内容附加到 XML 树中。

示例

下面的代码演示将有父级的元素添加到树中，以及将没有父级的元素添加到树中时的行为。

// Create a tree with a child element.
XElement xmlTree1 = new XElement("Root",
    new XElement("Child1", 1)
);

// Create an element that is not parented.
XElement child2 = new XElement("Child2", 2);

// Create a tree and add Child1 and Child2 to it.
XElement xmlTree2 = new XElement("Root",
    xmlTree1.Element("Child1"),
    child2
);

// Compare Child1 identity.
Console.WriteLine("Child1 was {0}",
    xmlTree1.Element("Child1") == xmlTree2.Element("Child1") ?
    "attached" : "cloned");

// Compare Child2 identity.
Console.WriteLine("Child2 was {0}",
    child2 == xmlTree2.Element("Child2") ?
    "attached" : "cloned");

' Create a tree with a child element.
Dim xmlTree1 As XElement = _
    <Root>
        <Child1>1</Child1>
    </Root>

' Create an element that is not parented.
Dim child2 As XElement = <Child2>2</Child2>

' Create a tree and add Child1 and Child2 to it.
Dim xmlTree2 As XElement = _
    <Root>
        <%= xmlTree1.<Child1>(0) %>
        <%= child2 %>
    </Root>

' Compare Child1 identity.
Console.WriteLine("Child1 was {0}", _
    IIf(xmlTree1.Element("Child1") Is xmlTree2.Element("Child1"), _
    "attached", "cloned"))

' Compare Child2 identity.
Console.WriteLine("Child2 was {0}", _
    IIf(child2 Is xmlTree2.Element("Child2"), _
    "attached", "cloned"))

此示例产生以下输出：

Child1 was cloned
Child2 was attached

请参见

概念

创建 XML 树