这个是我的servlet
public class UserServlet extends HttpServlet {
   
    public void doGet(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        
    }

    public void doPost(HttpServletRequest req, HttpServletResponse resp)
        throws ServletException, IOException {
        
        String username = req.getParameter("username");
        String password = req.getParameter("password");
        User user = new User();
        user.setUsername(username);
        user.setPassword(password);        
        if(DAOFactory.getUserDAOImpl().isLogin(user)){        
            req.getRequestDispatcher("/main.jsp").forward(req, resp);
            }
    }
   
    public void doAdd(HttpServletRequest req, HttpServletResponse resp)
        throws ServletException, IOException {
        System.out.println("操作成功");
        String username = req.getParameter("username");
        String password = req.getParameter("password");
        User user = new User();
        user.setUsername(username);
        user.setPassword(password);
        if(DAOFactory.getUserDAOImpl().Add(user)){
            System.out.println("添加成功");
        }
    }
   
}

web.xml
    <servlet>
        <servlet-name>user</servlet-name>
        <servlet-class>servlet.UserServlet</servlet-class>
    </servlet>
   
    <servlet-mapping>
        <servlet-name>user</servlet-name>
        <url-pattern>/user.do</url-pattern>
    </servlet-mapping>
   
    <servlet-mapping>
        <servlet-name>user</servlet-name>
        <url-pattern>/Add.do</url-pattern>
    </servlet-mapping>


为什么这个<form action="user.do" method="post">能执行成功
而这个<form action="Add.do" method="post">就不能执行？

应该可以的啊，一个</servlet>可以对应多个 <servlet-mapping>

你要是把错误贴出来。。我们就能更好的帮你解决

不能执行！！
servlet先初始化后，将request,response参数传递给了service()方法，这个方法会解析你的http请求类型（post or get?），然后就会调用相应的doPost() or doGet()方法去处理这个请求，你这样servlet不能解析出来，它怎么能执行呢？

一个servlet应该可以啊，楼主要不试试再多写一个servlet？