弄了一晚上还是404，找不到原因。Tomcat有打开

package com.imooc.OneServlet;

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 FirstServlet extends HttpServlet {

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

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

String html = "<h2 style='color:blue'>" + name + "</h2><hr/>";

System.out.println("返回给浏览器的数据为：" + html);

PrintWriter out = resp.getWriter();

out.print(html);// 将html发送回浏览器

}

}

<?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_3_1.xsd"

id="WebApp_ID" version="3.1">

<display-name>LearnServlet</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>

<servlet>

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

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

</servlet>

<servlet-mapping>

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

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

</servlet-mapping>

</web-app>