Java 从仪表板注销会导致错误404：请求的资源不可用

我需要从dahboard.jsp注销并转到index.jsp，但当我单击注销按钮时，它会显示如下错误消息

HTTP状态404-/Project/logout
类型状态报告
消息/项目/注销
说明请求的资源（/Project/logout）不可用。
ApacheTomcat/6.0.20

下面发布了dashboard.jsp和servlet登录和注销，其中可能有什么错误

dashboard.jsp

<div class="ends">
    <form action="logout" method="post" >
        <input type="submit" value="logout">
    </form>
</div>

---

检查

web.xml

文件是否正确映射了注销类。问题可能就在那里。否则，请共享完整的错误描述和web。

谢谢，伙计，web.xml中缺少注销类

package com.signin;

import java.io.IOException;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import com.db.DBCon;
/**
 * Servlet implementation class login
 */
public class login extends HttpServlet { 
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        response.setContentType("text/html");
        PrintWriter out = response.getWriter();

        String uid=request.getParameter("uid");
        String pwd=request.getParameter("pwd");


        try {
            DBCon dbc = new DBCon();
            if(dbc.validateLogin(uid, pwd))
            {
                HttpSession session=request.getSession();
                session.setAttribute("userid",uid);

                response.sendRedirect("dashboard.jsp");
            }
            else
                out.println("<center><h3>Sign in Failed!</h3><br><a href='index.jsp'>Go to Sign up page</a></center>");
            dbc.closeCon();
        }
        catch(Exception e){ e.printStackTrace(); }
    }
}

package com.signin;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;   
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

/**
 * Servlet implementation class logout
 */
public class logout extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub

        HttpSession session=request.getSession();
        session.removeAttribute("userid");
        session.invalidate();
        response.sendRedirect("index.jsp"); 
    }

}