如何在页面刷新时停止调用onbeforeunload事件

Question

我正在尝试更新数据库，同时用户关闭浏览器/点击。我尝试使用onbeforeunload函数及其工作正常，但即使在页面刷新。这是代码我试过的

MyJSP：

        <script type="text/javascript">
            var refresh=false;

            $(window).keydown(function(event){
                if(event.keyCode==116)
                    {       
                    refresh=true;
                    }
                    })

            $(window).on('beforeunload', function(){ 

                if(refresh==false)
                    {
                    $.get("BrowserCloseServlet", function() {

                    });
                    }

            });

      </script> 

MyServlet：

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        @SuppressWarnings("unused")
        String getId = request.getParameter("getid");
        Connection con = null;
        PreparedStatement pst = null;
        PreparedStatement pst2 = null;
        ResultSet rst = null;
        try {
            Class.forName("com.mysql.jdbc.Driver");
            con = DriverManager.getConnection("jdbc:mysql://localhost:3306/raptor1_5", "root", "");
            String query = "select NoOfCount from tbl_BroserCloseTable ";
            String query2 = "update tbl_BroserCloseTable set NoOfCount= ? where Sno= ?";
            // Statement st = con.createStatement();
            // st.executeUpdate("");
            pst = con.prepareStatement(query);

            rst = pst.executeQuery(query);
            if (rst.next()) {
                int count = rst.getInt(1);
                System.out.println("Actuall count is :" + count);
                count -= 1;

                pst2 = con.prepareStatement(query2);
                pst2.setInt(1, count);
                pst2.setInt(2, 1);
                pst2.executeUpdate();
                System.out.println("Updated successfully...");

            }

        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } finally {
            try {
                con.close();
                rst.close();
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

        }

    }

它的工作正常（单击f5按钮时不更新数据库）但如果用户单击刷新按钮，则调用该servlet页面并更新DB.I想在浏览器中单击刷新按钮时停止调用onbeforeunload。

更新：

我只想知道在浏览器中点击刷新按钮时如何使刷新= false; 。

如何做到这一点？