IDEA创建servlet，篇末有找不到servlet报404的原因

弄了好几天，终于知道哪里错了，满满的经验啊
本篇总结：90%的内容为正确创建servlet的步骤
末尾的10%为解决因找不到编写的servlet文件在Tomcat网页上报404的原因

<%@ page contentType="text/html;charset=UTF-8" language="java" %>

  
    
  
  
  
    

        输入英文句子：

        

        
    

  

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
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.io.PrintWriter;

@WebServlet(name = "Demo")
public class Demo extends HttpServlet {
    @Override
    public void init (ServletConfig config) throws ServletException {
        super.init(config);
    }

    @Override
    public void service (ServletRequest req, ServletResponse res) throws ServletException, IOException {
        req.setCharacterEncoding("utf-8");
        res.setContentType("text/html; charset=utf-8");
        PrintWriter out = res.getWriter();
        out.println("");
        String str = req.getParameter("english");
        if (str == null || str.length() == 0){
            return;
        }
        String [] word = str.split("[^a-zA-Z]+");
        int n = 0;
        try{
            for(int i = 0; i < word.length; i++) {
                if (word[i].length() >= 1){
                    n++;
                    out.print("
" + word[i]);
                }
            }
        }catch (NumberFormatException e){
            out.print(" " + e);
        }
        out.print("
句子中单词数目为：" + n);
        out.print("");
    }
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    }

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //设置网页响应类型
        response.setContentType("text/html");
        //实现具体操作
        PrintWriter out = response.getWriter();
        out.println("This is a new servlet page");
    }
}

配置Tomcat

注意：

在web.xml中的 和 ce.jsp中的
要保持一致，否则会找不到servlet文件，（这个问题困扰了我好几天！此处省略一万亿句脏话。。。。。。）