jspjava。lang.IllegalArgumentException:Page指令：导入的值无效

Question

我今天才面临这种错误。在那之前，我已经成功地跑了很多次。请帮我找出错误。下面给出了错误和代码

我正在做一个JSP项目。在使用Eclipse和Tomcat 9.0服务器运行项目时，我遇到了以下异常：

Message org.apache.jasper.JasperException: Unable to compile class for JSP

Description The server encountered an unexpected condition that prevented it from fulfilling the request.

Exception

org.apache.jasper.JasperException: org.apache.jasper.JasperException: Unable to compile class for JSP
    org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:605)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:423)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:385)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:329)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:733)
    servlet.userlogin.doPost(userlogin.java:32)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:652)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:733)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)

Root Cause

org.apache.jasper.JasperException: Unable to compile class for JSP
    org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:621)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:400)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:385)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:329)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:733)
    servlet.userlogin.doPost(userlogin.java:32)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:652)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:733)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)

Root Cause

java.lang.IllegalArgumentException: Page directive: invalid value for import
    org.apache.jasper.compiler.Node$PageDirective.validateImport(Node.java:619)
    org.apache.jasper.compiler.Node$PageDirective.addImport(Node.java:599)
    org.apache.jasper.compiler.Parser.parsePageDirective(Parser.java:366)
    org.apache.jasper.compiler.Parser.parseDirective(Parser.java:478)
    org.apache.jasper.compiler.Parser.parseFileDirectives(Parser.java:1797)
    org.apache.jasper.compiler.Parser.parse(Parser.java:141)
    org.apache.jasper.compiler.ParserController.doParse(ParserController.java:244)
    org.apache.jasper.compiler.ParserController.parseDirectives(ParserController.java:127)
    org.apache.jasper.compiler.Compiler.generateJava(Compiler.java:202)
    org.apache.jasper.compiler.Compiler.compile(Compiler.java:386)
    org.apache.jasper.compiler.Compiler.compile(Compiler.java:362)
    org.apache.jasper.compiler.Compiler.compile(Compiler.java:346)
    org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:605)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:400)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:385)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:329)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:733)
    servlet.userlogin.doPost(userlogin.java:32)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:652)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:733)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)

Note The full stack trace of the root cause is available in the server logs.
Apache Tomcat/9.0.41`

userlogin的代码。下面给出了java。这显示了第32行的错误，这一行是请求。getRequestDispatcher（“user.jsp”）。包括（请求、响应）

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import bean.userbean;
import dao.userdao;

@WebServlet("/userlogin")
public class userlogin extends HttpServlet {
   private static final long serialVersionUID = 1L;
   
   public userlogin() {
       super();
   }

   protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
       String email = request.getParameter("email");
       String password = request.getParameter("password");
       
       if(userdao.authenticate(email, password)) {
           HttpSession session = request.getSession();
           session.setAttribute("email",email);
           
           request.getRequestDispatcher("user.jsp").include(request, response);
       }else{
           request.getRequestDispatcher("userlogin.jsp").include(request, response);
           PrintWriter out=response.getWriter();
           out.println("<h3>Username or password error</h3>");
       }
   }

}

还有我的用户。jsp文件如下所示

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<%@ page import="java.io.PrintWriter;" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>

<h1>User Section</h1>

    <li><a href="sell.jsp">Sell</a></li>
    <li><a href="userlogin.jsp">Logout</a></li>
  
</body>
</html>

请帮我解决这个问题