elementlister.java

随书的代码

import org.jdom.*;
import org.jdom.input.SAXBuilder;
import java.io.IOException;
import java.util.*;


public class ElementLister {

  public static void main(String[] args) {
  
    if (args.length == 0) {
      System.out.println("Usage: java ElementLister URL"); 
      return;
    } 
      
    SAXBuilder builder = new SAXBuilder();
     
    try {
      Document doc = builder.build(args[0]);
      Element root = doc.getRootElement();
      listChildren(root, 0);      
    }
    // indicates a well-formedness error
    catch (JDOMException e) { 
      System.out.println(args[0] + " is not well-formed.");
      System.out.println(e.getMessage());
    }  
    catch (IOException e) { 
      System.out.println(e);
    }  
  
  }
  
  
  public static void listChildren(Element current, int depth) {
   
    printSpaces(depth);
    System.out.println(current.getName());
    List children = current.getChildren();
    Iterator iterator = children.iterator();
    while (iterator.hasNext()) {
      Element child = (Element) iterator.next();
      listChildren(child, depth+1);
    }
    
  }
  
  private static void printSpaces(int n) {
    
    for (int i = 0; i < n; i++) {
      System.out.print(' '); 
    }
    
  }

}