DOM解析器解析增删改学习笔记


import java.io.File;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.Result;
import javax.xml.transform.Source;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import org.junit.Test;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NodeList;

public class Demo2 {
//dom是否将空白字符当作一个有效的元素对待
public static void main(String[] args) throws Exception{
Document document = getDocument();
Element rootElement = document.getDocumentElement();
NodeList nodeList = rootElement.getChildNodes();
System.out.println("共有" + nodeList.getLength()+"个直接元素");
}
@Test
public void create() throws Exception{
Document document = getDocument();
Element newCarElement = document.createElement("汽车");
newCarElement.setTextContent("我的汽车");
Element rootElement = document.getDocumentElement();
//rootElement.appendChild(newCarElement);
rootElement.insertBefore(
newCarElement,
rootElement.getElementsByTagName("汽车").item(1));
write2xml(document);
}
@Test
public void update() throws Exception{
Document document = getDocument();
Element secondCarElement = (Element) document.getElementsByTagName("汽车").item(1);
secondCarElement.getElementsByTagName("产地").item(0).setTextContent("深圳");
secondCarElement.getElementsByTagName("车牌").item(0).getAttributes().getNamedItem("出产时间").setTextContent("2012年");
write2xml(document);
}
@Test
public void delete() throws Exception{
Document document = getDocument();
Element rootElement = document.getDocumentElement();
Element secondCarElement = (Element) rootElement.getElementsByTagName("汽车").item(1);
rootElement.removeChild(secondCarElement);
write2xml(document);
}
private void write2xml(Document document)throws Exception {
//将内存中的document对象写到外存的xml文件
TransformerFactory tf = TransformerFactory.newInstance();
Transformer transformer = tf.newTransformer();
//源
Source source = new DOMSource(document);
//目
Result result = new StreamResult(new File("src/xml/dom/car.xml"));
transformer.transform(source,result);
}
private static Document getDocument() throws Exception {
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
//设置dom解析器将空白字符过滤
factory.setIgnoringElementContentWhitespace(true);
DocumentBuilder domParser = factory.newDocumentBuilder();
Document document = domParser.parse(new File("src/xml/dom/car.xml"));
return document;
}
}


原文地址：http://blog.51cto.com/357712148/2104156