错误：尝试在tomcat服务器上运行时，包javax.servlet不存在

Question

C:\Program Files\Apache Software Foundation\Tomcat 9.0\webapps\FirstServlet\WEB-INF\classes>javac -classpath "C:\Program Files\Apache Software Foundation\Tomcat 9.0\lib\servelet-api.jar" FirstServlet.java


FirstServlet.java:1: error: package javax.servlet does not exist
import javax.servlet.*;
^
FirstServlet.java:2: error: package javax.servlet.http does not exist
import javax.servlet.http.*;
^
FirstServlet.java:5: error: cannot find symbol
public class FirstServlet extends HttpServlet
                                  ^
  symbol: class HttpServlet
FirstServlet.java:7: error: cannot find symbol
        public void doGet(HttpServletRequest req,HttpServletResponse res) throws ServletException , IOException
                          ^
  symbol:   class HttpServletRequest
  location: class FirstServlet
FirstServlet.java:7: error: cannot find symbol
        public void doGet(HttpServletRequest req,HttpServletResponse res) throws ServletException , IOException
                                                 ^
  symbol:   class HttpServletResponse
  location: class FirstServlet
FirstServlet.java:7: error: cannot find symbol
        public void doGet(HttpServletRequest req,HttpServletResponse res) throws ServletException , IOException
                                                                                 ^
  symbol:   class ServletException
  location: class FirstServlet
6 errors

这些是错误