xml解析（转）

转自：http://www.codesky.net/article/doc/201004/2010041703133.htm

java对XML文件的解析、节点的增加、删除操作总结

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1、java代码：
主要采用dom来进行操作

复制代码 代码如下:

package test;
import java.io.IOException;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerConfigurationException;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NodeList;
import org.w3c.dom.Text;
import org.xml.sax.SAXException;
public class XmlOprate {
Document doc;
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder;
NodeList imags;
String path;
public NodeList getImags() {
return imags;
}
public void setImags(NodeList imags) {
this.imags = imags;
}
/**
* 构造方法
* @param path:xml文件的路径
* @param nodes：要解析的xml节点名称
*/
public XmlOprate(String path) {
super();
this.path = path;
System.out.println(System.getProperty("user.dir"));
}
/**
* 解析XML
* @param path
*/
public void readXml(){
try {
builder = factory.newDocumentBuilder();
Document doc=builder.parse(path);
doc.normalize();
NodeList imags =doc.getElementsByTagName("imags");
this.setImags(imags);
for (int i=0;i<imags.getLength();i++){
Element link=(Element) imags.item(i);
System.out.print("title: ");
System.out.println(link.getElementsByTagName("title").item(0).getFirstChild().getNodeValue());
System.out.print("URL: ");
System.out.println(link.getElementsByTagName("url").item(0).getFirstChild().getNodeValue());
System.out.print("imgsrc: ");
System.out.println(link.getElementsByTagName("imgsrc").item(0).getFirstChild().getNodeValue());
System.out.println();
}
}catch (ParserConfigurationException e) {
e.printStackTrace();
} catch (SAXException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
/**
* addCode
* @param path
*/
public void addXmlCode(String imgsrc,String title,String url){
try {
builder = factory.newDocumentBuilder();
Document doc=builder.parse(path);
doc.normalize();
Text textseg;
Element imag=doc.createElement("imags");
Element linkimgsrc=doc.createElement("imgsrc");
textseg=doc.createTextNode(imgsrc);
linkimgsrc.appendChild(textseg);
imag.appendChild(linkimgsrc);
Element linktitle=doc.createElement("title");
textseg=doc.createTextNode(title);
linktitle.appendChild(textseg);
imag.appendChild(linktitle);
Element linkurl=doc.createElement("url");
textseg=doc.createTextNode(url);
linkurl.appendChild(textseg);
imag.appendChild(linkurl);
doc.getDocumentElement().appendChild(imag);
TransformerFactory tFactory =TransformerFactory.newInstance();
Transformer transformer;
transformer = tFactory.newTransformer();
DOMSource source = new DOMSource(doc);
StreamResult result = new StreamResult(new java.io.File(path));
transformer.transform(source, result);
}catch(Exception e){
}
}
/**
* delete xml code
* @param path
*/
public void delXmlCode(){
try {
builder = factory.newDocumentBuilder();
doc=builder.parse(path);
doc.normalize();
NodeList imags =doc.getElementsByTagName("imags");
Element elink=(Element) imags.item(0);
elink.removeChild(elink.getElementsByTagName("imgsrc").item(0));
elink.removeChild(elink.getElementsByTagName("title").item(0));
elink.removeChild(elink.getElementsByTagName("url").item(0));
doc.getFirstChild().removeChild(elink);
TransformerFactory tFactory =TransformerFactory.newInstance();
Transformer transformer = tFactory.newTransformer();
DOMSource source = new DOMSource(doc);
StreamResult result = new StreamResult(new java.io.File(path));
transformer.transform(source, result);
} catch (ParserConfigurationException e) {
e.printStackTrace();
} catch (SAXException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (TransformerConfigurationException e) {
e.printStackTrace();
} catch (TransformerException e) {
e.printStackTrace();
}
}
}

2、xml部分

复制代码 代码如下:

<?xml version="1.0" encoding="UTF-8" ?>
<root>
<imags>
<imgsrc>images/ad-01.jpg</imgsrc>
<title>胡志明市</title>
<url>http://torchrelay.beijing2008.cn/cn/journey/hochiminhcity/</url>
</imags>
<imags>
<imgsrc>images/ad-02.jpg</imgsrc>
<title>香港2</title>
<url>http://torchrelay.beijing2008.cn/cn/journey/hongkong/</url>
</imags>
</root>

3、总结：
看对xml操作的三个方法（读、写、删），他们的初始化语句都相同:

复制代码 代码如下:

builder = factory.newDocumentBuilder();
Document doc=builder.parse(path);
doc.normalize();

开始我打算把这部分相同的部分拿出来写在构造方法中，但是在测试中发现，这样总是会报空指针的错误（搞了我好久）;
而只是把
builder = factory.newDocumentBuilder();
放到builder的初始化语句中的时候，读没问题，但是当写或者删的时候也会报错；
所以就写成现在这样了，感觉有点乱乱的，但也没想到什么好的方法，就先贴到这里了，以后可能会用得着