用window.location.href为什么跳转不到servlet里??

删除
function empDelete(){

            var obj = document.getElementsByName("del_flag");

            var arr = new Array ();
            var obj = document.getElementsByName("del_flag");

            for (var i = 0;i<obj.length;i++) {
               if (obj[i].checked) {
                    arr.push(obj[i].value);

               } 
            }
            //alert(arr);

            if (arr.length == 0) {
                   alert("请选择要删除的记录!");

            } else {    

                window.location.href = "EmployeeDeleteServlet?cb="+arr;
                alert(arr);
            }

    }

servlet里：
String[] df= request.getParameterValues("cb");

        for(int j = 0;j<df.length;j++){
            System.out.println(df[j]);
        }

        Connection conn = null;
        PreparedStatement pst = null;
        ResultSet rs = null;
        int result = 0;

        try {
            conn = DBUtil.getConn("employee");
            if(df != null && df.length>0){
                for(int i = 0;i<df.length;i++){
                    pst = DBUtil.getPst(conn,"delete from EmpInfo where num = ?");
                    pst.setString(1, df[i]);
                    result = pst.executeUpdate();
                }
                if(result > 0){
                    response.sendRedirect("employee_list.jsp");
                }else{
                    request.setAttribute("errmsg", "删除数据失败");
                    request.getRequestDispatcher("error.jsp").forward(request, response);
                }
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }

}

window.location.href = "EmployeeDeleteServlet?cb="+arr;
在这上面打出一个alert语句。输出"EmployeeDeleteServlet?cb="+arr这一段，看看是不是地址错了

在跳转地址EmployeeDeleteServlet前面加上./ 这样 ./EmployeeDeleteServlet?cb