分享非常有用的Java程序 (关键代码)(六)---解析/读取XML 文件（重要）

XML文件 
<?xml version="1.0"?>  
<students> 
     <student>
          <name>John</name>
          <grade>B</grade>
          <age>12</age>
      </student>
      <student>
          <name>Mary</name>
          <grade>A</grade>
          <age>11</age> 
     </student>
      <student> 
         <name>Simon</name>
          <grade>A</grade>
          <age>18</age>
      </student>  
</students> 

 Java解析的代码：

package net.viralpatel.java.xmlparser; 
import java.io.File;   
import javax.xml.parsers.DocumentBuilder;  
import javax.xml.parsers.DocumentBuilderFactory;      
import org.w3c.dom.Document;   
import org.w3c.dom.Element;   
import org.w3c.dom.Node;   
import org.w3c.dom.NodeList;     
public class XMLParser {        
	public void getAllUserNames(String fileName) {    
		try {            
			DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();             
			DocumentBuilder db = dbf.newDocumentBuilder();          
			File file = new File(fileName);               
			if (file.exists()) {              
				Document doc = db.parse(file);            
				Element docEle = doc.getDocumentElement();                     
				// Print root element of the document            
				System.out.println("Root element of the document: "                         + docEle.getNodeName()); 
				NodeList studentList = docEle.getElementsByTagName("student");       
				// Print total student elements in document              
				System.out.println("Total students: " + studentList.getLength()); 
				if (studentList != null && studentList.getLength() > 0) {   
					for (int i = 0; i < studentList.getLength(); i++) {    
						Node node = studentList.item(i);                         
						if (node.getNodeType() == Node.ELEMENT_NODE) {    
							System.out.println("=====================");     
							Element e = (Element) node;                              
							NodeList nodeList = e.getElementsByTagName("name");
							System.out.println("Name: "     + nodeList.item(0).getChildNodes().item(0).getNodeValue());                    
							nodeList = e.getElementsByTagName("grade");   
							System.out.println("Grade: " + nodeList.item(0).getChildNodes().item(0).getNodeValue());
							nodeList = e.getElementsByTagName("age");    
							System.out.println("Age: " + nodeList.item(0).getChildNodes().item(0).getNodeValue());             
							}                       }                   
					} else {            
						System.exit(1);        
						}               }        
			} catch (Exception e) {          
				System.out.println(e);        
				}      
			}      
	public static void main(String[] args) {           
		XMLParser parser = new XMLParser();           
				}		
			parser.getAllUserNames("c:\\test.xml");     
		}  
	} 
}