xml解析 dom4j使用介绍

一、xml基础

xml(Extensible Markup Language)是一种可扩展标记语言，主要由以下部分构成：

头部：用于申明版本和编码等，<?xml version="1.0" encoding="UTF-8"?>

注释：可以输入任意字符， <!-- your comments -->

标记：即真正的内容。

CDATA：内容不被解析，一般用于放置一些特殊文本。

实体：用于申明特殊字符，或者给字符串取名。

二、dom4j的mvn配置（xml的解析库）

   <dependency>
  <groupId>dom4j</groupId>
  <artifactId>dom4j</artifactId>
  <version>1.6.1</version>
  </dependency>

三、xpath的mvn配置（xml的查询库）

   <dependency>
  <groupId>jaxen</groupId>
  <artifactId>jaxen</artifactId>
  <version>1.1.6</version>
  </dependency>

四、代码示例

代码下载：XmlDemo.java

工程文件：xml.rar

import java.io.*;
import java.util.*;
import org.dom4j.*;
import org.dom4j.io.*;

public class XmlDemo {

private static Route route = new Route(); 

private static Document loadXML(String filename) {
try {
SAXReader domReader = new SAXReader();
InputStream input = XmlDemo.class.getResourceAsStream(filename);
return domReader.read(input);
} catch (Exception e) {
e.printStackTrace();
return null;
}
}

private static void getRoute(Document doc) {
Element root = doc.getRootElement();
Element routeElem = root.element("route");
Element defElem = routeElem.element("default");
route.addDefault(defElem.getText());

Element items = routeElem.element("items");
List<Element> list = items.elements("item");
for (Element elem: list) {
route.addItem(elem.getText());
}
}

private static void selectElement(Document doc) {
List<Element> elems = doc.getRootElement()
.element("route")
.element("items")
.elements("item");
for (Element elemLocal: elems) {
System.out.println(elemLocal.getPath());
System.out.println(elemLocal.getName());
if (elemLocal.isTextOnly())
System.out.println(elemLocal.getText());
}
}

private static void iteratorXML(Document doc) {
Iterator iter = doc.getRootElement().elementIterator();
while (iter.hasNext())
System.out.println(((Element)iter.next()).getPath());
}

private static void xpathSample(Document doc) {
// detailed path
List<Element> list = doc.selectNodes("/config/route/items/item");
for(Element elem: list) {
System.out.println(elem.getText());
}

// any path
list = doc.selectNodes("//item");
for(Element elem: list) {
System.out.println(elem.getText());
}
}

public static void main(String[] args) {
Document doc = loadXML("/conf.xml");
getRoute(doc);
selectElement(doc);
iteratorXML(doc);
xpathSample(doc);
}
}

五、输出结果

/config/route/items/item
item
12001|1001|rules|12345678|rules.ser
/config/route/items/item
item
12001|1002|rules|12345678|rules.ser

/config/route

12001|1001|rules|12345678|rules.ser
12001|1002|rules|12345678|rules.ser
12001|1001|rules|12345678|rules.ser
12001|1002|rules|12345678|rules.ser