求救...为什么我的request.status值为0，而且responseText为空

这是我jsp代码：
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%@ page import="java.util.*,net.sf.json.*" %>
<%@ page import="House.*"%>
<%
String userId = request.getParameter("userId");
String userSecret = request.getParameter("userSecret");
String userType = request.getParameter("type");
if(userId==null||userId.equals("")){
out.print("error");
return;
}
if(userSecret==null||userSecret.equals("")){
out.print("error");
return;
}
if(userType==null||userType.equals("")){
out.print("error");
return;
}
int result=0;
LandingServe landing = new LandingServe();
if(userType.equals("1")){
result = landing.managerLanding(userId, userSecret);
}
else if(userType.equals("2")){
result = landing.sellerLanding(userId, userSecret);
}
else{
result = landing.purchaserLanding(userId, userSecret);
}
out.write(result);
%>