老师 这是我的代码 网页一直说未找到 不知道什么原因

package com.imooc.servlet;

import java.io.IOException;

import java.io.PrintWriter;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

public class ServletProj extends HttpServlet{

@Override

protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

  String category = req.getParameter("category");

  String html = "<h1 style='color:blue'>"+category+"<h1/>";

  PrintWriter out = resp.getWriter();

  out.println(html);

}

}

<?xml version="1.0" encoding="UTF-8"?>

<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd" id="WebApp_ID" version="4.0">

  <display-name>FirstServlet</display-name>

  <welcome-file-list>

    <welcome-file>index.html</welcome-file>

    <welcome-file>index.htm</welcome-file>

    <welcome-file>index.jsp</welcome-file>

    <welcome-file>default.html</welcome-file>

    <welcome-file>default.htm</welcome-file>

    <welcome-file>default.jsp</welcome-file>

  </welcome-file-list>

  <!-- 声明servlet -->

  <servlet>

  <!--servlet的别名 -->

    <servlet-name>first</servlet-name>

    <servlet-class>com.imooc.servlet.FirstServlet</servlet-class>

  </servlet>

  <!-- 将servlet与URL绑定 -->

  <servlet-mapping>

     <servlet-name>first</servlet-name>

     <url-pattern>/hi</url-pattern>

  </servlet-mapping>

   <servlet>

     <servlet-name>myservlet</servlet-name>

     <servlet-class>com.imooc.servlet.ServletProj</servlet-class>

  </servlet>

  <servlet-mapping>

    <servlet-name>myservlet</servlet-name>

    <url-pattern>/ShopServlet</url-pattern>

  </servlet-mapping>

</web-app>