我正在尝试使用Transformer.transform(Source, Result)输出我的XML文档，但它不会导出文档，只会抛出FileNotFoundException。我正在尝试使用Apache Tomcat将其导出到我的项目中的/WebContent/samples/users.xml。在Google上完成一些工作后，我在this上找到了关于所谓“错误”的bugs.sun.com页面。
以下是我的代码选择：
Document doc = newDocument();
Element rootElement = doc.createElement("homeworkManager");
Element sampleUserElement = doc.createElement("user");
// (set username and password)
Element sampleHomeworkElement1 = doc.createElement("homework");
// (set homework attributes)
sampleUserElement.appendChild(sampleHomeworkElement1);
rootElement.appendChild(sampleUserElement);
doc.appendChild(rootElement);
// HomeworkManager.getRealPath(String) is the same as HttpSession.getServletContext().getRealPath(String)
File output = new File(HomeworkManager.instance().getRealPath("/") + "/samples/users.xml");
Transformer transformer = TransformerFactory.newInstance().newTransformer();
transformer.setOutputProperty(OutputKeys.INDENT, "yes");
transformer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "2");
transformer.transform(new DOMSource(doc), new StreamResult(output)); // EXCEPTION THROWN HERE
这是堆栈跟踪：
javax.xml.transform.TransformerException: java.io.FileNotFoundException: ...\workspace\.metadata\.plugins\org.eclipse.wst.server.core\tmp0\wtpwebapps\Homework Manager\samples\users.xml (The system cannot find the path specified)
at com.sun.org.apache.xalan.internal.xsltc.trax.TransformerImpl.getOutputHandler(TransformerImpl.java:493)
at com.sun.org.apache.xalan.internal.xsltc.trax.TransformerImpl.transform(TransformerImpl.java:302)
at net.dean.homeworkmanager.UserManager.createSampleXMLFile(UserManager.java:215)
at org.apache.jsp.index_jsp._jspService(index_jsp.java:91)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:929)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1002)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:585)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
at java.lang.Thread.run(Thread.java:722)
Caused by: java.io.FileNotFoundException: (...)\workspace\.metadata\.plugins\org.eclipse.wst.server.core\tmp0\wtpwebapps\Homework Manager\samples\users.xml (The system cannot find the path specified)
at java.io.FileOutputStream.open(Native Method)
at java.io.FileOutputStream.<init>(FileOutputStream.java:212)
at java.io.FileOutputStream.<init>(FileOutputStream.java:104)
at com.sun.org.apache.xalan.internal.xsltc.trax.TransformerImpl.getOutputHandler(TransformerImpl.java:466)
... 25 more
你可以说，我很困惑。任何建议都会非常感激。
编辑：这只发生在Web项目上。我可以使用完全相同的代码在桌面应用程序上导出我的文档。
编辑2 ：即使我创建了目录和 users.xml，也不会修改该文件。而是在(...)\workspace\.metadata\.plugins\org.eclipse.wst.server.core\tmp0\wtpwebapps\Homework Manager\samples\users.xml