java中 怎么创建xml文件

package com.xml;

import java.io.File;
import java.io.IOException;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.Source;
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.Text;

public class CreatXML {
 
 String filename;
 DocumentBuilderFactory factory;
 DocumentBuilder builder;
 Document doc;
 
 public CreatXML(String filename)throws ParserConfigurationException{
  this.filename=filename;
  factory=DocumentBuilderFactory.newInstance();
  builder=factory.newDocumentBuilder();
  doc=builder.newDocument();
 }
 
 
 public void setChildTxt(String childtxt,Element father){
  Text txt=doc.createTextNode(childtxt);
  father.appendChild(txt);
 }
 
 public Element setChild(String child,Element father){
  Element newChild=doc.createElement(child);
  father.appendChild(newChild);
  return newChild;
 }
 
 public Document getDoc(){
  return doc;
 }
 
 //生成xml文件
 public boolean creat(){
  boolean ret= false;
  //创建文件
  File file=new File(filename);
  String path=file.getPath();
  System.out.println("path="+path);
  if(!file.exists()||!file.isFile()){
   try {
    file.createNewFile();
   } catch (IOException e) {
    e.printStackTrace();
   }
  }
  StreamResult streamResult=new StreamResult(file);
  Source inputSource=new DOMSource(doc);
  TransformerFactory transformerFactory=TransformerFactory.newInstance();
  Transformer transformer;
  
  try {
   transformer=transformerFactory.newTransformer();
   transformer.transform(inputSource, streamResult);
   ret=true;
  } catch (TransformerConfigurationException e) {
   e.printStackTrace();
  }catch(TransformerException e){
   e.printStackTrace();
  }
  return ret;
 }
 
 public static void main(String[] args) {
  try {
   CreatXML xml=new CreatXML("C://dd.xml/");
   boolean flag=xml.creat();
   System.out.println(flag);
   
  } catch (ParserConfigurationException e) {
   // TODO 自动生成 catch 块
   e.printStackTrace();
  }
  
 }
}