如何使用XPath提取xml文档数据

import java.util.List; import org.dom4j.Document;import org.dom4j.Node;import org.dom4j.io.SAXReader;import org.junit.Test;/* * 使用XPath查找xml文档数据 *  */public class DemoXPath {  @Test  //输出book.xml中所有price元素节点的文本值  public void test1() throws Exception {    SAXReader reader = new SAXReader();    Document document = reader.read("src/main/java/book.xml");    List<? extends Node> selectNodes = document.selectNodes("//price");    for(Node node : selectNodes) {      String text = node.getText();      System.out.println(text);    }  }     @Test  //输出book.xml中第二本书的price元素节点的文本值  public void test2() throws Exception {    SAXReader reader = new SAXReader();    Document document = reader.read("src/main/java/book.xml");    Node selectSingleNode = document.selectSingleNode("/bookshelf/book[2]/price");    String text = selectSingleNode.getText();    System.out.println(text);  }     @Test  //输出book.xml中第二本书和第三本书的author元素节点的文本值  public void test3() throws Exception {    SAXReader reader = new SAXReader();    Document document = reader.read("src/main/java/book.xml");    List<? extends Node> selectSingleNode = document.selectNodes("/bookshelf/book[position()>1]/author");    for (Node node : selectSingleNode) {      String text = node.getText();      System.out.println(text);    }  }     @Test  //输出book.xml中含有属性id的所有name的文本值  public void test4() throws Exception {    SAXReader reader = new SAXReader();    Document document = reader.read("src/main/java/book.xml");    List<? extends Node> selectSingleNode = document.selectNodes("//name[@id]");    for (Node node : selectSingleNode) {      String text = node.getText();      System.out.println(text);    }  }     @Test  //输出book.xml中含有属性id="1111"的name的文本值  public void test5() throws Exception {    SAXReader reader = new SAXReader();    Document document = reader.read("src/main/java/book.xml");    Node selectSingleNode = document.selectSingleNode("//name[@id=/"1111/"]");    String text = selectSingleNode.getText();    System.out.println(text);  }     @Test  //输出book.xml中含有属性id="1112"的book的author的文本值  public void test6() throws Exception {    SAXReader reader = new SAXReader();    Document document = reader.read("src/main/java/book.xml");    Node selectSingleNode = document.selectSingleNode("//book[name[@id=/"1112/"]]/author");    String text = selectSingleNode.getText();    System.out.println(text);  }     @Test  //输出book.xml中第一本book的id的属性值  public void test7() throws Exception {    SAXReader reader = new SAXReader();    Document document = reader.read("src/main/java/book.xml");    Node selectSingleNode = document.selectSingleNode("//book[1]/name");    String text = selectSingleNode.valueOf("attribute::id");//获取id属性    System.out.println(text);  }     @Test  //输出book.xml中book的name的id的属性值为1112的对应的sn的属性值  public void test8() throws Exception {    SAXReader reader = new SAXReader();    Document document = reader.read("src/main/java/book.xml");    List<? extends Node> selectNodes = document.selectNodes("//book/name");    for (Node node : selectNodes) {      if(node.valueOf("attribute::id").equals("1112")) {        System.out.println(node.valueOf("attribute::sn"));      }    }  }}

 <dependency>     <groupId>junit</groupId>     <artifactId>junit</artifactId>     <version>4.11</version>    </dependency>    <dependency>     <groupId>log4j</groupId>     <artifactId>log4j</artifactId>     <version>1.2.17</version>    </dependency>    <dependency>     <groupId>dom4j</groupId>     <artifactId>dom4j</artifactId>    </dependency><dependency> <groupId>jaxen</groupId> <artifactId>jaxen</artifactId> <version>1.1.6</version></dependency>

 <?xml version="1.0" encoding="utf-8"?> <bookshelf> <book>  <name id="1111" sn="sdd8">Tomorrow</name>   <author>Hiskell</author>   <price>$40</price> </book>  <book>  <name id="1112" sn="sdd9">Goodbye to You</name>   <author>Giddle</author>   <price>$25</price> </book>  <book>  <name id="1113" sn="sdd0">Sea and Old</name>   <author>Heminw</author>   <price>$28</price> </book></bookshelf>