Xpath可以快速的定位和查找所需要的字符串或是数据。工欲善其事必先利其器，要想快速的开发和处理查找xml数据，学习和掌握xpath是必不可少的。那就开始吧。
示例的student.xml文件。
<?xml version="1.0"?> <students> <student id="1001"> <name>张三</name> <score>85</score> <email>zhangsan@126.com</email> <age>20</age> <address> <province>广东</province> <city>广州</city> </address> <description> aaa <h1>bbb</h1> ccc </description> </student> <student id="1002"> <name>李四</name> <score>79</score> <email>lisi@126.com</email> <age>24</age> <address> <province>广东</province> <city>深圳</city> </address> <description> 111 <h1>222</h1> 333 </description> </student> <student id="1003"> <name>王五</name> <score>92</score> <email>wangwu@126.com</email> <age>24</age> <address> <province>广东</province> <city>汕头</city> </address> <description> xxx <h1>yyy</h1> zzz </description> </student> </students>
编写测试的java代码。
package com.suntek.test.xpath;
import java.util.List;
import org.jdom.Attribute;
import org.jdom.Document;
import org.jdom.Element;
import org.jdom.Text;
import org.jdom.input.SAXBuilder;
import org.jdom.xpath.XPath;
public class XpathTest {
/**
* 取得文档
* @return
* @throws Exception
*/
public static Document getDocument() throws Exception {
SAXBuilder builder = new SAXBuilder();
return builder.build(System.class.getResourceAsStream("/student.xml"));
}
/**
* 格式化标签
*/
public static String formatElement(Element elem) {
StringBuffer sb = new StringBuffer();
sb.append("<" + elem.getName());
List attributes = elem.getAttributes();
for(int i = 0; i < attributes.size(); i ++) {
Attribute attribute = (Attribute) attributes.get(i);
sb.append(" " + attribute.getName() + "=" + attribute.getValue());
}
sb.append(">");
//这个方法可以取得Text,Element,Comment,ProcessingInstruction,CDATA,EntityRef.等集合的列表
List children = elem.getContent();
for(int i = 0; i < children.size(); i ++) {
Object o = children.get(i);
if(o instanceof Text) {
sb.append(((Text)o).getText());
} else if(o instanceof Element) {
sb.append(formatElement((Element)o));
}
}
sb.append("</" + elem.getName() + ">");
return sb.toString();
}
/**
* 取得所有的学生
* @throws Exception
*/
public static void getAllStudent() throws Exception {
Document doc = getDocument();
List list = XPath.selectNodes(doc, "//student");
for(int i = 0; i < list.size(); i ++) {
Element elem = (Element) list.get(i);
System.out.println(formatElement(elem));
}
}
/**
* 取得符合一定分数条件的学生
* @param score 分数
* @param above 是否高于
* @throws Exception
*/
public static void getStudent(String score, boolean above) throws Exception {
Document doc = getDocument();
String exp = "";
if(above) {
exp = ">=";
} else {
exp = "<";
}
List list = XPath.selectNodes(doc, "//student[score" + exp + score+"]");
for(int i = 0; i < list.size(); i ++) {
Element elem = (Element) list.get(i);
System.out.println(formatElement(elem));
}
}
/**
* 假设学生这个节点的信息太多，你不希望取得它的整个节点然后再便利他的子节点找出你要的信息，
* 而是通过xpath直接定位到你要的信息。这样就要通过xpath来循环迭代。
*/
public static void getAllStudentByXpath() throws Exception {
Document doc = getDocument();
Document newDoc = new Document();
List list = XPath.selectNodes(doc, "//student");
for(int i = 0; i < list.size(); i ++) {
Element elem = (Element) list.get(i);
elem.detach();
newDoc.setRootElement(elem);
Element e = (Element) XPath.selectSingleNode(newDoc, "/student/name");
System.out.println(formatElement(e));
}
}
public static void getStudentNameAndDescription() throws Exception {
Document doc = getDocument();
Document newDoc = new Document();
List list = XPath.selectNodes(doc, "//student");
for(int i = 0; i < list.size(); i ++) {
Element elem = (Element) list.get(i);
elem.detach();
newDoc.setRootElement(elem);
StringBuffer sb = new StringBuffer();
Text t = null;
t = (Text) XPath.selectSingleNode(newDoc, "/student/name/text()");
sb.append(t.getTextTrim()+";");
t = (Text) XPath.selectSingleNode(newDoc, "/student/description/text()[1]");
sb.append(t.getTextNormalize()+";");
t = (Text) XPath.selectSingleNode(newDoc, "/student/description/h1/text()");
sb.append(t.getTextNormalize()+";");
t = (Text) XPath.selectSingleNode(newDoc, "/student/description/text()[2]");
sb.append(t.getTextNormalize());
System.out.println(sb.toString());
}
}
public static void main(String[] args) throws Exception {
getAllStudent();
System.out.println("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~");
getStudent("80", true);
System.out.println("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~");
getAllStudentByXpath();
System.out.println("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~");
getStudentNameAndDescription();
}
}运行结果如下：
<student id=1001>
<name>张三</name>
<score>85</score>
<email>zhangsan@126.com</email>
<age>20</age>
<address>
<province>广东</province>
<city>广州</city>
</address>
<description>
aaa
<h1>bbb</h1>
ccc
</description>
</student>
<student id=1002>
<name>李四</name>
<score>79</score>
<email>lisi@126.com</email>
<age>24</age>
<address>
<province>广东</province>
<city>深圳</city>
</address>
<description>
111
<h1>222</h1>
333
</description>
</student>
<student id=1003>
<name>王五</name>
<score>92</score>
<email>wangwu@126.com</email>
<age>24</age>
<address>
<province>广东</province>
<city>汕头</city>
</address>
<description>
xxx
<h1>yyy</h1>
zzz
</description>
</student>
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
<student id=1001>
<name>张三</name>
<score>85</score>
<email>zhangsan@126.com</email>
<age>20</age>
<address>
<province>广东</province>
<city>广州</city>
</address>
<description>
aaa
<h1>bbb</h1>
ccc
</description>
</student>
<student id=1003>
<name>王五</name>
<score>92</score>
<email>wangwu@126.com</email>
<age>24</age>
<address>
<province>广东</province>
<city>汕头</city>
</address>
<description>
xxx
<h1>yyy</h1>
zzz
</description>
</student>
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
<name>张三</name>
<name>李四</name>
<name>王五</name>
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
张三;aaa;bbb;ccc
李四;111;222;333
王五;xxx;yyy;zzz
扫一扫
被折叠的 条评论
为什么被折叠?
到【灌水乐园】发言
