使用eclipse开发servlet

package cn.itcast;
import java.io.IOException;

import javax.servlet.GenericServlet;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

public class ServletDemo1 extends GenericServlet {

    @Override
    public void service(ServletRequest req, ServletResponse res)
            throws ServletException, IOException {
        
        res.getOutputStream().write("hello servlet".getBytes());

    }

}

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.4" 
    xmlns="http://java.sun.com/xml/ns/j2ee" 
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee 
    http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
    
<servlet>
    <servlet-name>ServletDemo1</servlet-name>
    <servlet-class>cn.itcast.ServletDemo1</servlet-class>
</servlet>

<servlet-mapping>
    <servlet-name>ServletDemo1</servlet-name>
    <url-pattern>/ServletDemo1</url-pattern>
</servlet-mapping>
    
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
</web-app>