XPath syntax:
XPath path expressions used to select XML node or group of nodes.
1, example:
<?xml version="1.0" encoding="UTF-8"?> <bookstore> <book> <title lang="en">Harry Potter</title> <price>29.99</price> </book> <book> <title lang="en">Learning XML</title> <price>39.95</price> </book> </bookstore>
2, select the node:
The following table lists the most useful path expressions:
| expression | description |
|---|---|
| Node name | Select all nodes having the node name is |
| / | Select from the root (absolute path) |
| // | From the current node selection regardless of where |
| . | Selecting the current node |
| .. | Selecting a parent node |
| @ | Select Properties |
Applied to the previous example, the following results:
| Path expression | result |
|---|---|
| bookstore | Select all nodes named "bookstore" of |
| /bookstore | Select the root element bookstore |
| bookstore/book | Select all book nodes from child nodes of the bookstore |
| //book | Select all book nodes from the text regardless of where |
| bookstore//book | Select all nodes in the book in subsequent bookstore |
| // @ lang | Select all "lang" attribute in the text |
3, predicate (Predicates):
The predicate is used to query a particular node or a node having a particular value.
Predicate always framed by a pair of square brackets.
Following table:
| Path Expression | Result |
|---|---|
| /bookstore/book[1] | Select a bookstore first sub-node named book |
| /bookstore/book[last()] | Bookstore select last child node named book |
| /bookstore/book[last()-1] | Select bookstore penultimate sub-node named book |
| /bookstore/book[position()<3] | Bookstore book select the first two child nodes |
| //title[@lang] | Select all nodes having title "lang" attribute |
| // title [@ lang = 'and'] | Select all nodes having title "lang" attribute and is 'en' is |
| /bookstore/book[price>35.00] | Select bookstore child node in price> book node 35.00 |
| /bookstore/book[price>35.00]/title | Select the sub-node title of the bookstore price> book node 35.00 |
4, select the unknown node:
| Tsuhaifu | description |
|---|---|
| * | Matches any element node |
| @* | Attribute node matches any |
| node() | Matches any node of any type |
As follows:
| Path expression | result |
|---|---|
| /bookstore/* | Select all the child nodes bookstore |
| //* | Select all of the text elements in nodes |
| //title[@*] | Select an element having a title attribute |
5, a plurality of selected paths:
Using | operator to multi-path selection.
As follows:
| Path expression | result |
|---|---|
| //book/title | //book/price | Select all book nodes in the title and price node |
| //title | //price | Selected title and price text node |
| /bookstore/book/title | //price | Select the title elements of the book element of the bookstore and all price elements |