java request,setAttribute()

我在servlet代码中有：sendStr = monaco.getSend(request.getParameter("operation"));            
                        if (sendStr.equals("Send")){                                
                              RequestDispatcher requestDispatcher = request.getRequestDispatcher("Prototype.jsp?Prototype.jsp?location="+ request.getParameter("location"));         
                              requestDispatcher.forward(request, response); 
                        }
                        else if(sendStr.equals("Review")){
                              RequestDispatcher requestDispatcher = request.getRequestDispatcher("Prototype.jsp?location="+ request.getParameter("location"));
                              request.setAttribute("isSuccess", "S");                              
                              requestDispatcher.forward(request, response); 
                              System.out.print("send");
                        }
                  }
                  request.setAttribute("message",message);
在jsp中： 
 <script type="text/javascript">
    function openReview(){
        <%
            String location (String)request.getParameter("location");                                         
            String isSuccess = (String)request.getAttribute("isSuccess");                       
            String isTipText = (String) request.getAttribute("tiptext");
            if(isSuccess != null && "S".equals(isSuccess) && isTipText.equals("")){
         %>
         window.open ('Review.jsp', 'newwindow', 'height=600, width=400, top=200,left=400, toolbar=no, menubar=no, scrollbars=no, resizable=no,location=no, status=no'); 
          <%                                                          
            }
           %>                          
     }
  </script>
<body onload="openReview()">正常操作是当我点击了按钮review时再打开，这样使可以的，问题是当我每次刷新时，总会执行一次window.open ('Review.jsp', 'newwindow', 'height=600, width=400, top=200,left=400, toolbar=no, menubar=no, scrollbars=no, resizable=no,location=no, status=no'); 
难道是因为request.setAttribute()有缓存吗