At 04:57 AM 7/7/2004, you wrote:
Sorry if this is considered spamming the list ....
Speaking of storing stuff in session scope. I've developed what I think is a handy class which I think it useful for
when I want to store something like a search in a session variable.
For instance if I want to page through it ( using displaytags.org (10 out of 10)) or simply if I don't want to fetch
from the database time and time again.
By default the data expires on an hourly basis. And if a different combination of parameters is sent it expires
the cached stuff.
Here is the class
snip= package ie.jestate.struts.client;
import java.util.Date;
/**
* @author Bryan Hunt
*/
//TODO:Perhaps I should be generating a MD5 or something but I can't see a good reason to use any more CPU
public class HashGenerator {
private StringBuffer buffer;
/** * */ public HashGenerator() { super(); buffer = new StringBuffer(50); // TODO Auto-generated constructor stub }
/** * @param urbanAreas */ public void add(Integer[] array,String fieldname) { for (int i = 0; i < array.length; i++) { Integer integer = array[i]; buffer.append(integer); } buffer.append(fieldname); buffer.append("-"); }
/** * @param priceRangeStart */ public void add(Integer integer,String fieldname) { // TODO Auto-generated method stub buffer.append(integer); buffer.append(fieldname); buffer.append("-"); }
/** * @return */ public String getHash() {
//I append the hour onto the end of the string so that a hash will //only be good for a max of one hour. Date date = new Date();
return buffer.toString()+ "-" + new Integer(date.getHours()); }
}
=snip
And here is example usage. snip= /* * Created on 24-Jun-2004 */ package ie.jestate.struts.client;
import ie.jestate.struts.BaseAction;
import java.util.Set;
import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession;
import org.apache.struts.action.ActionForm; import org.apache.struts.action.ActionForward; import org.apache.struts.action.ActionMapping; import org.apache.struts.action.DynaActionForm;
/** * @author Bryan Hunt * */ public class ForSaleSearchAction extends BaseAction {
/* (non-Javadoc)
* @see org.apache.struts.action.Action#execute(org.apache.struts.action.ActionMapping, org.apache.struts.action.ActionForm, javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
*/
public ActionForward execute(
ActionMapping actionMapping,
ActionForm actionForm,
HttpServletRequest request,
HttpServletResponse response)
throws Exception {
//TODO: Database based initialization of the countries collection
DynaActionForm dynaform = (DynaActionForm) actionForm;
HttpSession session = request.getSession();
String forSalePropertiesSearchCheckSum = (String) session.getAttribute(Constants.FOR_SALE_CHECK_SUM);
String newForSalePropertiesSearchCheckSum = null;
Integer[] urbanAreas = (Integer[]) dynaform.get("urbanAreas"); Integer priceRangeStart = (Integer) dynaform.get("priceRangeStart"); Integer priceRangeEnd = (Integer) dynaform.get("priceRangeEnd"); Integer[] propertyTypes = (Integer[]) dynaform.get("propertyTypes");
HashGenerator hashGenerator = new HashGenerator();
hashGenerator.add(urbanAreas,"urbanAreas");
hashGenerator.add(priceRangeStart,"priceRangeStart");
hashGenerator.add(priceRangeEnd,"priceRangeEnd");
hashGenerator.add(propertyTypes,"propertyTypes");
newForSalePropertiesSearchCheckSum = hashGenerator.getHash();
if(forSalePropertiesSearchCheckSum != null && forSalePropertiesSearchCheckSum.equals(newForSalePropertiesSearchCheckSum)) {
System.out.println("Checksums match");
}
if (forSalePropertiesSearchCheckSum == null
|| !forSalePropertiesSearchCheckSum.equals(newForSalePropertiesSearchCheckSum)){
Set forSaleProperties = findForSaleProperties( urbanAreas, priceRangeStart, priceRangeEnd, propertyTypes);
session.setAttribute(Constants.FOR_SALE_PROPERTIES_SEARCH_RESULT, forSaleProperties);
session.setAttribute(
Constants.FOR_SALE_CHECK_SUM,
newForSalePropertiesSearchCheckSum);
// TODO:Add logging functionality
System.out.println("Returning fresh search results");
} else /* if (
session.getAttribute("forSalePropertiesSearchCheckSum").equals( forSalePropertiesSearchCheckSum)) */ { //This means that it is the same search, just called again. //TODO:Add logging functionality System.out.println("Returning cached search results");
}
//TODO: Decent logging is needed here System.out.println(forSalePropertiesSearchCheckSum); System.out.println(newForSalePropertiesSearchCheckSum); System.out.println(" ---------------------------------------" );
return actionMapping.findForward("success"); } }
=snip
Christina Siena wrote:
I recently developed an application with a complex UI. One of the pages required querying the database based on user selection and re-displaying the page with the retrieved data and any previous existing user selections. Four different fields can trigger a db query resulting in page re-display and validations can also result in page re-display. Each time the page is re-displayed, the "state" of the page must be "remembered" from the last time it was displayed. (still with me so far?) Most of the data re
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