The Xpath‘s javadoc could be got from the Dom4j‘s javadoc.

There are some simple regulation you must follow:

　　1.When you want to use specific single node:

　　　　/AAA

　　　　/AAA/CCC

　　2.When you want to use all the nodes which have the same name:

　　　　//BBB

　　　　//DDD/CCC

　　3. * represent all the nodes in the specific path:

　　　　/AAA/*

　　　　//*     --------->  all the nodes

　　4.The expression which has the square brackets could further specify the node. The number in the bracket gives the position you select/

　　　　/AAA[1]

　　　　//BBB/CCC[last()]

　　5.The attribute will be got by the @

　　　　//@id

　　　　/AAA[@id]

But after knowing the regulation , where should we put it?

　　//Get the document object

　　SAXReader reader = new SAXReader();

　　Document document = reader.read("");

　　//get the data of node via document‘s selecNodes() or selectSingleNode()

　　List<Node> nodes = document.selectNodes(" you can set your regulation here!!");

　　Node node = document.selectSingleNode(" you can set your regulation here!!");

A powerful tool to parse xml -- Xpath!