关于xml的操作，Java报xml文件不存在的错误 急！

  DocumentBuilderFactory dbf=DocumentBuilderFactory.newInstance();
    DocumentBuilder db=dbf.newDocumentBuilder();
    File fl=new File("d:/xml/userdatabase.xml");
    doc =db.parse(fl);
    Element root=(Element)doc.getElementsByTagName("database").item(0);
    NodeList nl=root.getElementsByTagName("user");

上述第四行，报这个错，D盘下的文件是存在的 ，不解 ？请高手指点
Exception in thread "main" java.io.FileNotFoundException: d:\xml\userdatabase.xml (指定されたファイルが見つかりません。)
at java.io.FileInputStream.open(Native Method)
at java.io.FileInputStream. <init>(FileInputStream.java:106)
at java.io.FileInputStream. <init>(FileInputStream.java:66)
at sun.net.www.protocol.file.FileURLConnection.connect(FileURLConnection.java:70)
at sun.net.www.protocol.file.FileURLConnection.getInputStream(FileURLConnection.java:161)
at com.sun.org.apache.xerces.internal.impl.XMLEntityManager.setupCurrentEntity(XMLEntityManager.java:973)
at com.sun.org.apache.xerces.internal.impl.XMLVersionDetector.determineDocVersion(XMLVersionDetector.java:184)
at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:798)
at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:764)