该点及下面派生的所有点的全部信息，只读如果要求book点的xml,返回“<book level="1"><Name>c++</Name><Price>20</Price><info><k>1</k></info><info><k>2</k></info></book>”，如果Name的xml，返回“<Name>c++</Name>”
2．1．4 text
Represents the text content of the node or the concatenated text representing the node and its descendants. Read/write
该点及下面派生的所有点的全部节点值，可读可写
<price>20</price>
则text为20
"Name"节点的text为"c++"
2．1．5 attributes
Contains the list of attributes for this node
返回属性的集合。
2．1．6 nodeName
Returns the qualified name for attribute, document type, element, entity, or notation nodes. Returns a fixed string for all
other node types. Read-only
该节点名称
"Name"节点的nodeName为"Name","book"节点的nodeName为"book"
2．1．7 documentElement
Contains the root element of the document
xml的根节点
上面的xml的根节点为"book"
2．1．8 nextSibling
Contains the next sibling of the node in the parent's child list. Read-only.
下一个兄弟节点，只读
2．1．9 childNodes
Contains a node list containing the child nodes
所有的子节点。
2．1．10 firstChild
Contains the first child of the node
第一个子节点
2．1．11 lastChild
Returns the last child node
最后一个子节点
2．2 方法
2．2．1 loadXML
Loads an XML document using the supplied string
2．2．2 load
Loads an XML document from the specified locati
参数的路径为服务器端的，是相对路径
2．2．3 selectSingleNode
Applies the specified pattern-matching operation to this node's context and returns the first matching node
返回第一个匹配的项
2．2．4 selectNodes
Applies the specified pattern-matching operation to this node's context and returns the list of matching nodes as IXMLDOMNodeList
符合条件的所有项。
2．2．5 getElementsByTagName
Returns a collection of elements that have the specified name
