这里无法正确编译FirstServlet，而且左边也没有target目录

相关代码：

<?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.wxb.servlet.FirstServlet</servlet-class>
        
    </servlet>
    <servlet-mapping>
        <servlet-name>first</servlet-name>
        <url-pattern>/hi</url-pattern>
    </servlet-mapping>
</web-app>

相关代码：package com.wxb.servlet;
import javax.servlet.ServletException;
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 req, HttpServletResponse resp) throws ServletException, IOException {
        String name=req.getParameter("name");
        String html = "<h1 style='color:red'>,"+name+"!</h1><hr/>";
        System.out.println("返回给浏览器的相应内容为："+html);
        PrintWriter out = resp.getWriter();
        out.println(html);
    }
}

浏览器访问报错：

FirstServlet未正确实例化