404错误：request.getRequestDispatcher方法

package com.demo.servlet;

import com.demo.dao.UsersDAO;
import com.demo.entity.Users;

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 java.io.IOException;
import java.util.List;

@WebServlet("/index")
public class FindAllServlet extends HttpServlet {
    private UsersDAO usersDAO = new UsersDAO();

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

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        List<Users> list = usersDAO.findAll();
        System.out.println("List = " + list);
        request.setAttribute("usersList", list);

        request.getRequestDispatcher("index.jsp").forward(request, response);
    }
}
控制台可以打印出List，跳转后报错404。关于request.getRequestDispatcher方法其后的路径此处为什么可
以直接写("index.jsp")，而不需要写成(request.getContextPath()+"index.jsp")?