ofbiz birt script request null

<method name="open"><![CDATA[customers = null;
try {
var customerId;
    var req=reportContext.getHttpServletRequest();
    if(req==null)
    {
    customerId="10010";
    }
if(req!=null)
{
if(req.getParameter("customerId")!=null)
{
        customerId = req.getParameter("customerId");
        
        }else
        {
         customerId="10000";
        }
    }
    customers = delegator.findByAndCache("customer", UtilMisc.toMap("customerId", customerId));
} catch (e) {
    Debug.logError(e, module);
}
totalRow = 0;
countOfRow = 0;
if (customers) {
    totalRow = customers.size();
}]]>怎样取得url中的参数，为什么request NULL ofbiz集成的birt为什么没有request对象呢？