XPath轴

XPath 轴
翻译：Linyupark / 2006-03-24

The XML Example Document
XML举例文档

We will use the following XML document in the examples below.
我么将使用该XML文档进行下面的举例说明

<?xml version="1.0" encoding="ISO-8859-1"?>

<bookstore>

<book>
  <title lang="eng">Harry Potter</title>
  <price>29.99</price>
</book>

<book>
  <title lang="eng">Learning XML</title>
  <price>39.95</price>
</book>

</bookstore>

---

XPath Axes
XPath轴

An axis defines a node-set relative to the current node.
轴定义了相对于当前节的节集

轴名	结果
ancestor	Selects all ancestors (parent, grandparent, etc.) of the current node[选择了当前节的所有祖（父，祖父，等等）]
ancestor-or-self	Selects all ancestors (parent, grandparent, etc.) of the current node and the current node itself[选择当前节的所有祖并且还有当前节自己]
attribute	Selects all attributes of the current node[选择所有当前节的属性]
child	Selects all children of the current node[选择所有当前节的子]
descendant	Selects all descendants (children, grandchildren, etc.) of the current node[选择所有当前节的孙（子，孙子，等等）]
descendant-or-self	Selects all descendants (children, grandchildren, etc.) of the current node and the current node itself[选择当前节的所有孙以及它本身]
following	Selects everything in the document after the closing tag of the current node[选择所有在关闭当前节标签后的所有内容]
following-sibling	Selects all siblings after the current node[选择所有当前节后的兄]
namespace	Selects all namespace nodes of the current node[选择所有当前节的命名空间]
parent	Selects the parent of the current node[选择当前节的父]
preceding	Selects everything in the document that is before the start tag of the current node[选择当前节之前的所有内容]
preceding-sibling	Selects all siblings before the current node[选择所有当前节之前的兄]
self	Selects the current node[选择当前节]

---

Location Path Expression
路径表达试定位

A location path can be absolute or relative.
定位路径可以是绝对的也可以是相对的

An absolute location path starts with a slash ( / ) and a relative
location path does not. In both cases the location path consists of one
or more steps, each separated by a slash:
绝对定位的路径由(/)开始，而相对定位就不这样。定位的路径由一个或多个步骤所组成，每部分由(/)相分隔：

An absolute location path:

/step/step/...

A relative location path:

step/step/...

Each step is evaluated against the nodes in the current node-set.
在当前的节集中每步的赋值是逆向的

A step consists of:

• an axis (defines the tree-relationship between the selected nodes and the current node)
• a node-test (identifies a node within an axis)[在轴中鉴定节]
• zero or more predicates (to further refine the selected node-set)[0个或多个谓语可以来更好的选择节]

The syntax for a location step is:
定位的语法

axisname::nodetest[predicate]

Examples
实例

Example	结果
child::book	Selects all book nodes that are children of the current node[选择当前节点下所有为book的子节点]
attribute::lang	Selects the lang attribute of the current node[选择当前节点下所有属性为lang的内容]
child::*	Selects all children of the current node[选择当前节下所有的子节]
attribute::*	Selects all attributes of the current node[选择当前节所有的属性]
child::text()	Selects all text child nodes of the current node[选择当前节点所有子节点的文字]
child::node()	Selects all child nodes of the current node[选择所有当前节点的子节点]
descendant::book	Selects all book descendants of the current node[选择当前节点所有为book的孙节点]
ancestor::book	Selects all book ancestors of the current node[选择所有当前祖节点为book的节点]
ancestor-or-self::book	Selects all book ancestors of the current node - and the current as well if it is a book node[当前节点和其祖节点为book的节点]
child::*/child::price	Selects all price grandchildren of the current node[当前节点所有含price的孙子节点]