Servlets Eclipse:ServletConfig对象在调用getServletConfig()时返回NULL

Servlets Eclipse:ServletConfig对象在调用getServletConfig()时返回NULL,servlets,Servlets,这是我的密码。请帮我解决这个问题。我是servlet新手,我正在尽力解决它,但我无能为力 public class InsertData extends GenericServlet{ public void service(ServletRequest request, ServletResponse response) throws ServletException, IOException { PrintWriter pw = null ;

这是我的密码。请帮我解决这个问题。我是servlet新手,我正在尽力解决它,但我无能为力

public class InsertData extends GenericServlet{    

    public void service(ServletRequest request, ServletResponse response) throws ServletException, IOException {
        PrintWriter pw = null ;
        ServletConfig conf = getServletConfig(); // This is giving null everytime i m checked it in webpage
        String str = cont.getInitParameter("username");
        pw  = response.getWriter();
        pw.println("<html><body><b>conf</b></body><html>"); 
        }
}
公共类InsertData扩展了GenericServlet{
公共void服务(ServletRequest请求、ServletResponse响应)抛出ServletException、IOException{
PrintWriter pw=null;
ServletConfig conf=getServletConfig();//每次我在网页中检查它时,都会给出null
字符串str=cont.getInitParameter(“用户名”);
pw=response.getWriter();
pw.println(“conf”);
}
}
这是我的web.xml文件:

 <web-app>
  <servlet>
    <servlet-name>s1</servlet-name>
    <servlet-class>InsertData</servlet-class>
    <init-param>
        <param-name>username</param-name>
        <param-value>mydb</param-value>
    </init-param>
  </servlet>
  <servlet-mapping>
    <servlet-name>s1</servlet-name>
    <url-pattern>/InsertData</url-pattern>
  </servlet-mapping>
  <welcome-file-list>
    <welcome-file>home.html</welcome-file>  
  </welcome-file-list>
</web-app>

s1
插入数据
用户名
mydb
s1
/插入数据
home.html

如何运行servlet?在eclipse中使用Apache服务器。