ArrayList<Book> booklist=parsexml();

SAXTransformerFactory factory=(SAXTransformerFactory)SAXTransformerFactory.newInstance();

try {

TransformerHandler tfh=factory.newTransformerHandler();

Transformer tf=tfh.getTransformer();

tf.setOutputProperty(OutputKeys.ENCODING, "UTF-8");

tf.setOutputProperty(OutputKeys.INDENT, "yes");

File f=new File("src/rec/newbooks.xml");

if(!f.exists()){

f.createNewFile(); 

}  

Result res = new StreamResult(new FileOutputStream(f));

tfh.setResult(res);

tfh.startDocument();

AttributesImpl atts = new AttributesImpl();

tfh.startElement("", "", "bookstore", atts);

tfh.endElement("", "","bookstore");

tfh.endDocument()

运行之后，，没有生成newbooks.xml是怎么回事？？？？？？？？