生成xml选择直接输出字符串不生成文件和生成文件

import java.io.ByteArrayOutputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;
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.Result;
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;
 
class XmlImpl{
    private Document document;
 
    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("scores");
          this.document.appendChild(root);
          Element employee = this.document.createElement("employee");
          Element name = this.document.createElement("name");
          name.appendChild(this.document.createTextNode("wangchenyang"));
          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("26"));
          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");
            //直接输出字符串，不写入文件
            ByteArrayOutputStream outStream = new ByteArrayOutputStream();
            OutputStreamWriter write = new OutputStreamWriter(outStream);
            Result result = new StreamResult(write);
            Transformer xformer = TransformerFactory.newInstance()
            .newTransformer();
//            xformer.setOutputProperty(OutputKeys.ENCODING,"gb2312");
            xformer.setOutputProperty(OutputKeys.STANDALONE,"yes");
            xformer.transform(source,result);
            System.out.println(outStream.toString());
            
            //生成文件
            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(fileName);
             
            NodeList employees = document.getChildNodes();
            for (int i = 0; i < employees.getLength(); i++) {
                Node employee = employees.item(i);
                NodeList employeeInfo = employee.getChildNodes();
                for (int j = 0; j < employeeInfo.getLength(); j++) {
                    Node node = employeeInfo.item(j);
                    NodeList employeeMeta = node.getChildNodes();
                    for (int k = 0; k < employeeMeta.getLength(); k++) {
                        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());
        }
    }
}
public class xmLTest {
	 
    public static void main(String args[]){
        XmlImpl dd=new XmlImpl();
        String str="D:/grade.xml";
        dd.init();
        dd.createXml(str);    //创建xml
        dd.parserXml(str);    //读取xml
    }
}