Servlet与jsp相互转发重定向出现404和500错误

当我们在项目中，实现页面挑战中，总是会遇到明明路径是匹配的，但是在实际操作中会报错
如

如果你的电脑是自己的，绝壁会出现这样的错误，所以我们最好手动用contextPath读取项目路径
比如在jsp的form表单设置成

<%--
  Created by IntelliJ IDEA.
  User: chen Pen
  Date: 2022/5/17
  Time: 14:01
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>


    



    
    
    

在servlet中

package com.javaweb;

import util.Constant;

import javax.servlet.*;
import javax.servlet.http.*;
import java.io.IOException;

public class SServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String username = request.getParameter("username");
        
        String contextPath =request.getContextPath();

        if (username.equals("admin")){
            request.getSession().setAttribute(Constant.USER_SESSION,request.getSession().getId());
            System.out.println("22222222");
            response.sendRedirect(contextPath+"/sys/sesssion.jsp");

        }
        response.sendRedirect(contextPath+"/error.jsp");
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    doGet(request,response);
    }
}

一般都能完美解决问题。