Question

关于request.getSession())问题及获取tomcat的根目录路径

我的类继承了HttpServllet 定义了HttpServlletRequest 按道理可以用request.getSession().getServletContext().getRealPath("/")可以获取tomcat的绝对路径
但是报错
Exception in thread "main" java.lang.NullPointerException
at com.test.utils.XML.GetPath(XML.java:22)
at com.test.utils.XML.main(XML.java:45)

public class XML extends HttpServlet{

public static String GetPath(){
HttpServletRequest request = null;

//String path=request.getSession().getServletContext().getRealPath("/");
System.out.println("path1="+request.getSession());
System.out.println("path2="+request.getSession().getServletContext());
System.out.println("path3="+request.getSession().getServletContext().getRealPath("/"));
//InputStream is=TestAction.class.getClassLoader().getResourceAsStream("test.txt");
return null;
}
public static void main(String[] args) {

try {

DocumentBuilderFactory factory = DocumentBuilderFactory
.newInstance();
DocumentBuilder builder = factory.newDocumentBuilder();
Document document = builder.parse(new File("E:\\新建 文本文档 (3).xml"));
Element rootElement = document.getDocumentElement();
NodeList list = rootElement.getElementsByTagName("Header");
Element element = (Element) list.item(0);
//System.out.println(element.getChildNodes().item(0).getNodeValue());
} catch (Exception e) {
System.out.println("exception:" + e.getMessage());
}

GetPath();
}
}

Answer 1

单继承，是不够的，还要真是一个Servlet，才能。

Answer 2

空指针错误了 //String path=request.getSession().getServletContext().getRealPath("/");
这个request对象为空？

追问

我测试了下request.getSession() 报的空指针

追答

那就是你没得到request了