JDom解析xml学习笔记
http://wuhongyu.iteye.com/blog/361842
xml是一种广为使用的可扩展标记语言，java中解析xml的方式有很多，最常用的像jdom、dom4j、sax等等。前两天刚好有个程序需要解析xml，就学了下jdom，写了个小例子，这里做个学习笔记。
要使用jdom解析xml文件，需要下载jdom的包，我使用的是jdom-1.1。解压之后，将lib文件夹下的.jar文件以及build文件夹下的jdom.jar拷贝到工程文件夹下，然后就可以使用jdom操作xml文件了。
一、读取xml文件
假设有这样一个xml文件：
- <?xml version="1.0" encoding="UTF-8"?>
- <sys-config>
- <jdbc-info>
- <driver-class-name>oracle.jdbc.driver.OracleDriver</driver-class-name>
- <url>jdbc:oracle:thin:@localhost:1521:database</url>
- <user-name>why</user-name>
- <password>why</password>
- </jdbc-info>
- <provinces-info>
- <province id="hlj" name="黑龙江">
- <city id="harb">哈尔滨</city>
- <city id="nj">嫩江</city>
- </province>
- <province id="jl" name="吉林"></province>
- </provinces-info>
- </sys-config>
<?xml version="1.0" encoding="UTF-8"?> <sys-config> <jdbc-info> <driver-class-name>oracle.jdbc.driver.OracleDriver</driver-class-name> <url>jdbc:oracle:thin:@localhost:1521:database</url> <user-name>why</user-name> <password>why</password> </jdbc-info> <provinces-info> <province id="hlj" name="黑龙江"> <city id="harb">哈尔滨</city> <city id="nj">嫩江</city> </province> <province id="jl" name="吉林"></province> </provinces-info> </sys-config>
首先，用 org.jdom.input.SAXBuilder 这个类取得要操作的xml文件，会返回一个 org.jdom.Document 对象，这里需要做一下异常处理。然后，取得这个xml文件的根节点，org.jdom.Element 代表xml文件中的一个节点，取得跟节点后，便可以读取xml文件中的信息。利用 org.jdom.xpath.XPath 可以取得xml中的任意制定的节点中的信息。
例如，要取得上面文件中的 <jdbc-info> 下的 <driver-class-name> 中的内容，先取得这个节点Element driverClassNameElement = (Element)XPath.selectSingleNode(rootEle, "//sys-config/jdbc-info/driver-class-name")，注意，根节点前要使用两个 "/" ，然后，用 driverClassNameElement.getText() 便可以取得这个节点下的信息。
如果一个节点下有多个名称相同的子节点，可以用XPath.selectNodes()方法取得多个子节点的List，遍历这个List就可以操作各个子节点的内容了。
下面是我写的读取上面xml文件的例子，比起文字描述更直观一些吧：
- package com.why.jdom;
- import java.io.IOException;
- import java.util.Iterator;
- import java.util.List;
- import org.jdom.input.SAXBuilder;
- import org.jdom.xpath.XPath;
- import org.jdom.Document;
- import org.jdom.Element;
- import org.jdom.JDOMException;
- public class ReadXML {
- /**
- * @param args
- */
- public static void main(String[] args) {
- SAXBuilder sax = new SAXBuilder();
- try {
- Document doc = sax.build("src/config.xml");
- Element rootEle = doc.getRootElement();
- Element driverClassNameElement = (Element)XPath.selectSingleNode(rootEle, "//sys-config/jdbc-info/driver-class-name");
- String driverClassName = driverClassNameElement.getText();
- System.out.println("driverClassName = " + driverClassName);
- List provinceList = XPath.selectNodes(rootEle, "//sys-config/provinces-info/province");
- for(Iterator it = provinceList.iterator();it.hasNext();){
- Element provinceEle = (Element)it.next();
- String proId = provinceEle.getAttributeValue("id");
- String proName = provinceEle.getAttributeValue("name");
- System.out.println("provinceId = " + proId + " provinceName = " + proName);
- List cityEleList = (List)provinceEle.getChildren("city");
- for(Iterator cityIt = cityEleList.iterator();cityIt.hasNext();){
- Element cityEle = (Element)cityIt.next();
- String cityId = cityEle.getAttributeValue("id");
- String cityName = cityEle.getText();
- System.out.println(" cityId = " + cityId + " cityName = " + cityName);
- }
- }
- } catch (JDOMException e) {
- // TODO 自动生成 catch 块
- e.printStackTrace();
- } catch (IOException e) {
- // TODO 自动生成 catch 块
- e.printStackTrace();
- }
- }
- }
package com.why.jdom;
import java.io.IOException;
import java.util.Iterator;
import java.util.List;
import org.jdom.input.SAXBuilder;
import org.jdom.xpath.XPath;
import org.jdom.Document;
import org.jdom.Element;
import org.jdom.JDOMException;
public class ReadXML {
/**
* @param args
*/
public static void main(String[] args) {
SAXBuilder sax = new SAXBuilder();
try {
Document doc = sax.build("src/config.xml");
Element rootEle = doc.getRootElement();
Element driverClassNameElement = (Element)XPath.selectSingleNode(rootEle, "//sys-config/jdbc-info/driver-class-name");
String driverClassName = driverClassNameElement.getText();
System.out.println("driverClassName = " + driverClassName);
List provinceList = XPath.selectNodes(rootEle, "//sys-config/provinces-info/province");
for(Iterator it = provinceList.iterator();it.hasNext();){
Element provinceEle = (Element)it.next();
String proId = provinceEle.getAttributeValue("id");
String proName = provinceEle.getAttributeValue("name");
System.out.println("provinceId = " + proId + " provinceName = " + proName);
List cityEleList = (List)provinceEle.getChildren("city");
for(Iterator cityIt = cityEleList.iterator();cityIt.hasNext();){
Element cityEle = (Element)cityIt.next();
String cityId = cityEle.getAttributeValue("id");
String cityName = cityEle.getText();
System.out.println(" cityId = " + cityId + " cityName = " + cityName);
}
}
} catch (JDOMException e) {
// TODO 自动生成 catch 块
e.printStackTrace();
} catch (IOException e) {
// TODO 自动生成 catch 块
e.printStackTrace();
}
}
}
二、写xml文件
写xml文件与读取xml文件的操作类似，利用 org.jdom.output.XMLOutputter 就可以将处理好的xml输出到文件了。可以设置文件的编码方式，不过一般使用UTF-8就可以了。代码如下：
- package com.why.jdom;
- import java.io.FileNotFoundException;
- import java.io.FileOutputStream;
- import java.io.IOException;
- import org.jdom.Document;
- import org.jdom.Element;
- import org.jdom.output.XMLOutputter;
- public class WriteXML {
- /**
- * @param args
- */
- public static void main(String[] args) {
- // TODO 自动生成方法存根
- Element rootEle = new Element("sys-config");
- Element provincesEle = new Element("provinces-info");
- Element provinceEle = new Element("province");
- provinceEle.setAttribute("id","hlj");
- provinceEle.setAttribute("name","黑龙江省");
- Element cityEle1 = new Element("city");
- cityEle1.setAttribute("id","harb");
- cityEle1.addContent("哈尔滨");
- Element cityEle2 = new Element("city");
- cityEle2.setAttribute("id","nj");
- cityEle2.addContent("嫩江");
- provinceEle.addContent(cityEle1);
- provinceEle.addContent(cityEle2);
- provincesEle.addContent(provinceEle);
- rootEle.addContent(provincesEle);
- Document doc = new Document(rootEle);
- XMLOutputter out = new XMLOutputter();
- // out.setFormat(Format.getCompactFormat().setEncoding("GBK"));//设置文件编码，默认为UTF-8
- String xmlStr = out.outputString(doc);
- System.out.println(xmlStr);
- try {
- out.output(doc, new FileOutputStream("c:/test.xml"));
- } catch (FileNotFoundException e) {
- // TODO 自动生成 catch 块
- e.printStackTrace();
- } catch (IOException e) {
- // TODO 自动生成 catch 块
- e.printStackTrace();
- }
- }
- }
http://www.cnblogs.com/ling_yun/archive/2011/01/19/1939674.html
下面是xml文件:
<?xml version="1.0" encoding="UTF-8"?>
<persons>
<person perid="1001">
<name>lhu</name>
<age>89</age>
<address>安徽淮北</address>
<sex>男</sex>
</person>
<person perid="1002">
<name>we</name>
<age>56</age>
<address>北京海淀</address>
<sex>女</sex>
</person>
</persons>
下面是解析上面的xml文件:
通过JDOM来解析,需要借助第三方的组件.jdom.jar,网上有1.0的版本下载
package cn.com.jdom;
import java.io.File;
import java.io.IOException;
import java.util.Iterator;
import java.util.List;
import org.jdom.Attribute;
import org.jdom.Document;
import org.jdom.Element;
import org.jdom.JDOMException;
import org.jdom.ProcessingInstruction;
import org.jdom.input.SAXBuilder;
import com.sun.xml.internal.bind.v2.runtime.Name;
/**
* jdom解析xml文件
*
* @author ly *
*/
public class JDomXML {
public JDomXML() {
}
/**
* 解析xml文件
* @param xmlFile
*/
public void parseXml(File xmlFile) {
SAXBuilder sax = new SAXBuilder();//在内存中建立一个sax文档模型
try {
Document xmlDom = sax.build(xmlFile);//创建文档
//获得文件的根元素
Element root = xmlDom.getRootElement();
System.out.println("根元素是:"+root.getName());
//获得根元素的子节点
List childList = root.getChildren();
Iterator listIt = childList.iterator();
while(listIt.hasNext()){
Element element = (Element)listIt.next();
System.out.println("孩子结点是:"+element.getName());
}
//获得第一个孩子结点
Element firstChild = (Element) childList.get(0);
//获得孩子结点的属性
List attrList = firstChild.getAttributes();
Iterator attrIt = attrList.iterator();
while(attrIt.hasNext()){
Attribute attr = (Attribute ) attrIt.next();
System.out.println("第一个元素的属性是:"+attr.getName());
//获得属性的值
System.out.println("属性的值是:"+attr.getValue());
//获得属性的类型
System.out.println("属性的类型是:"+attr.getAttributeType());
}
List sonList = firstChild.getChildren();
Iterator sonIt = sonList.iterator();
while(sonIt.hasNext()){
Element temp = (Element)sonIt.next();
System.out.println("属性"+temp.getName()+"的值是:"+temp.getValue());
}
} catch (JDOMException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
JDomXML test = new JDomXML();
test.parseXml(new File("persons.xml"));
}
}