访问项目报404

package com.hydra.servlet;

import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;

public class FirstServlet extends HttpServlet {
    @Override
    protected void service(HttpServletRequest request, HttpServletResponse response) throws IOException {
        String name = request.getParameter("name");
        String html = "<h1>" + name + "<h1><br>";
        System.out.println("返回给浏览器的数据为：" + html);
        PrintWriter out = response.getWriter();
        out.println(html);

    }
}

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
         version="3.1">
    <servlet>
        <servlet-name>first</servlet-name>
        <servlet-class>com.hydra.servlet.FirstServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>first</servlet-name>
        <url-pattern>/hi</url-pattern>
    </servlet-mapping>
</web-app>

问答区的解决方案都尝试过，ide控制台也没有报错信息