DOM生成和解析XML文档

DOM生成和解析XML文档

为 XML 文档的已解析版本定义了一组接口。解析器读入整个文档，然后构建一个驻留内存的树结构，然后代码就可以使用 DOM 接口来操作这个树结构。优点：整个文档树在内存中，便于操作；支持删除、修改、重新排列等多种功能；缺点：将整个文档调入内存（包括无用的节点），浪费时间和空间；使用场合：一旦解析了文档还需多次访问这些数据；硬件资源充足（内存、CPU）。 ( XML在不同的语言里解析方式都是一样的,只不过实现的语法不同而已。基本的解析方式有两种,一种叫SAX，另一种叫DOM。SAX是基于事件流的解析,DOM是基于XML文档树结构的解析。还有就是借助插件（DOM4J、JDOM等插件）来解析)

package e; 
import java.io.FileInputStream; 
import java.io.FileNotFoundException; 
import java.io.FileOutputStream; 
import java.io.IOException; 
import java.io.InputStream; 
import java.io.PrintWriter; 
import javax.xml.parsers.DocumentBuilder; 
import javax.xml.parsers.DocumentBuilderFactory; 
import javax.xml.parsers.ParserConfigurationException; 
import javax.xml.transform.OutputKeys; 
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.Node; 
import org.w3c.dom.NodeList; 
import org.xml.sax.SAXException; 
/** 
 * 
 * @author hongliang.dinghl 
 * DOM生成与解析XML文档 
 */ 
public class DomDemo { 
	private Document document; 
	private String fileName; 
	public void init() { 
		try { 
			DocumentBuilderFactory factory = DocumentBuilderFactory 
			.newInstance(); 
			DocumentBuilder builder = factory.newDocumentBuilder(); 
			this.document = builder.newDocument(); 
		} catch (ParserConfigurationException e) { 
			System.out.println(e.getMessage()); 
		} 
	} 
	public void createXml(String fileName) { 
		Element root = this.document.createElement("employees"); 
		this.document.appendChild(root); 
		Element employee = this.document.createElement("employee"); 
		Element name = this.document.createElement("name"); 
		name.appendChild(this.document.createTextNode("丁宏亮")); 
		employee.appendChild(name); 
		Element sex = this.document.createElement("sex"); 
		sex.appendChild(this.document.createTextNode("m")); 
		employee.appendChild(sex); 
		Element age = this.document.createElement("age"); 
		age.appendChild(this.document.createTextNode("30")); 
		employee.appendChild(age); 
		root.appendChild(employee); 
		TransformerFactory tf = TransformerFactory.newInstance(); 
		try { 
			Transformer transformer = tf.newTransformer(); 
			DOMSource source = new DOMSource(document); 
			transformer.setOutputProperty(OutputKeys.ENCODING, "gb2312"); 
			transformer.setOutputProperty(OutputKeys.INDENT, "yes"); 
			PrintWriter pw = new PrintWriter(new FileOutputStream(fileName)); 
			StreamResult result = new StreamResult(pw); 
			transformer.transform(source, result); 
			System.out.println("生成XML文件成功!"); 
		} catch (TransformerConfigurationException e) { 
			System.out.println(e.getMessage()); 
		} catch (IllegalArgumentException e) { 
			System.out.println(e.getMessage()); 
		} catch (FileNotFoundException e) { 
			System.out.println(e.getMessage()); 
		} catch (TransformerException e) { 
			System.out.println(e.getMessage()); 
		} 
	} 
	public void parserXml(String fileName) { 
		try { 
			DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); 
			DocumentBuilder db = dbf.newDocumentBuilder(); 
			Document document = db.parse("c:\\111.txt");
			/*
			 	<?xml version="1.0" encoding="UTF-8"?> 
				<employees> 
				<employee> 
				<name>ddviplinux</name> 
				<sex>m</sex> 
				<age>30</age> 
				</employee> 
				<employee> 
				<name>ddvi222</name> 
				<sex>m</sex> 
				<age>56</age> 
				</employee> 
				</employees>
			*/
			NodeList employees = document.getChildNodes(); 
			for (int i = 0; i < employees.getLength(); i++) { 
				Node employee = employees.item(i); //employees
				NodeList employeeInfo = employee.getChildNodes(); 
				for (int j = 0; j < employeeInfo.getLength(); j++) { 
					Node node = employeeInfo.item(j); 
					NodeList employeeMeta = node.getChildNodes(); //employee
					for (int k = 0; k < employeeMeta.getLength(); k++) { 
						if("name".equals(employeeMeta.item(k).getNodeName()) || "sex".equals(employeeMeta.item(k).getNodeName())  || "age".equals(employeeMeta.item(k).getNodeName())){
							System.out.println(employeeMeta.item(k).getNodeName() 
									+ ":" + employeeMeta.item(k).getTextContent()); 
						}
						
					} 
				} 
			} 
			System.out.println("解析完毕"); 
		} catch (FileNotFoundException e) { 
			System.out.println(e.getMessage()); 
		} catch (ParserConfigurationException e) { 
			System.out.println(e.getMessage()); 
		} catch (SAXException e) { 
			System.out.println(e.getMessage()); 
		} catch (IOException e) { 
			System.out.println(e.getMessage()); 
		} 
	} 
}