Четыре варианта SPI: лица без гражданства, использующие хэшбэнгсы

The SPITutMainLoadRequestListener class is the same as the stateful hashbang example.

In stateless the SPITutMainLoadRequestListener.processRequest(…) method will be called in two different scenarios:

1. When the servlet receives a new load request of this template that is when initially loading the page, conventional use
2. When a stateless event has been received in server specifying the template of this document (load phase of stateless event processing)

In this tutorial the same template is going to be used for the initial load and for stateless event processing, this is the simplest (not mandatory) option, in this case is appropriated because the template is very simple, everything is in the same position when the page is loaded and when processing stateless events, there is no need of locById attributes in this tutorial (please read first about how ItsNat support stateless apps in Manual, a tutorial about using stateless mode exists).

A new SPITutMainDocument instance is created per call (load request), this instance holds an ItsNatHTMLDocument object which represents the client document (page) being loaded as usual.

Unlike the stateful mode, SPITutMainDocument objects are not going to be retained in server because the page template was registered «stateless» calling docTemplate.setEventsEnabled(false);, and when a SPITutMainDocument is created to dispatch a stateless event, this document object is ever stateless (not retained in server) because the nature of stateless event processing.

The class SPITutMainDocument inherits from SPIStlessHashbangMainDocument the main class of the mini-framework to create SPI SEO compatible stateless based on hashbang web sites under the package org.itsnat.spistlesshashbang.

Again we are using a mini-framework in this tutorial:

1. org.itsnat.spi: generic classes, same as all other SPI web site tutorialsClasses: SPIMainDocumentConfig, SPIMainDocument, SPIState, SPIStateDescriptor 
2. org.itsnat.spistless: stateless specificClass: SPIStlessMainDocument 
3. org.itsnat.spistlesshashbang: stateless and hashbang processing specificClasses: SPIStlessHashbangMainDocument 

We are not going to explain the classes of the package org.itsnat.spi because they are the same as seen in stateful hashbang tutorial. Note there is no SPIStlessState class (not needed).

Main Page Processing Stateless

Now is time to step down to describe how the mini-framework manages a stateless web site.

There is only one class into the package org.itsnat.spistless: SPIStlessMainDocument.

package org.itsnat.spistless;

import org.itsnat.spi.SPIMainDocumentConfig;
import org.itsnat.spi.SPIStateDescriptor;
import org.itsnat.core.ClientDocument;
import org.itsnat.core.event.ItsNatEventDOMStateless;
import org.itsnat.core.http.ItsNatHttpServletRequest;
import org.itsnat.core.http.ItsNatHttpServletResponse;
import org.itsnat.spi.SPIMainDocument;
import org.itsnat.spi.SPIState;
import org.w3c.dom.DocumentFragment;
import org.w3c.dom.Element;
import org.w3c.dom.events.Event;
import org.w3c.dom.events.EventListener;

public abstract class SPIStlessMainDocument extends SPIMainDocument
{
    public SPIStlessMainDocument(ItsNatHttpServletRequest request, ItsNatHttpServletResponse response,SPIMainDocumentConfig config)
    {
        super(request, response,config);

        if (itsNatDoc.isCreatedByStatelessEvent())
        {
            EventListener listener = new EventListener()
            {
                @Override
                public void handleEvent(Event evt)
                {
                    ItsNatEventDOMStateless itsNatEvt = (ItsNatEventDOMStateless)evt;

                    String stateName = (String)itsNatEvt.getExtraParam("state_name");

                    changeState(stateName,itsNatEvt);
                }
            };

            itsNatDoc.addEventListener(listener);
        }
    }

    public SPIState changeState(String stateName)
    {
        return changeState(stateName,null);
    }

    public SPIState changeState(String stateName,ItsNatEventDOMStateless itsNatEvt)
    {
        SPIStateDescriptor stateDesc = config.getSPIStateDescriptor(stateName);
        if (stateDesc == null)
        {
            return changeState(config.getNotFoundStateName(),itsNatEvt);
        }

        // Cleaning previous state:
        if (!itsNatDoc.isLoading())
        {
            ClientDocument clientDoc = itsNatDoc.getClientDocumentOwner();
            String contentParentRef = clientDoc.getScriptUtil().getNodeReference(config.getContentParentElement());
            clientDoc.addCodeToSend("window.spiSite.removeChildren(" + contentParentRef + ");");  // ".innerHTML = '';"
        }

        // Setting new state:
        changeActiveMenu(stateName);

        String fragmentName = stateDesc.isMainLevel() ? stateName : getFirstLevelStateName(stateName);
        DocumentFragment frag = loadDocumentFragment(fragmentName);
        config.getContentParentElement().appendChild(frag);

        return createSPIState(stateDesc,itsNatEvt);
    }

    public abstract SPIState createSPIState(SPIStateDescriptor stateDesc,ItsNatEventDOMStateless itsNatEvt);


    public void changeActiveMenu(String stateName)
    {
        String mainMenuItemName = getFirstLevelStateName(stateName);

        Element currentMenuItemElem = config.getMenuElement(mainMenuItemName);
        for(Element menuItemElem : config.getMenuElementMap().values())
        {
            onChangeActiveMenu(menuItemElem,(currentMenuItemElem == menuItemElem));
        }
    }

    public abstract void onChangeActiveMenu(Element menuItemElem,boolean active);
}

if (itsNatDoc.isCreatedByStatelessEvent())
{
    EventListener listener = new EventListener()
    {
        @Override
        public void handleEvent(Event evt)
        {
            ItsNatEventDOMStateless itsNatEvt = (ItsNatEventDOMStateless)evt;

            String stateName = (String)itsNatEvt.getExtraParam("state_name");

            changeState(stateName,itsNatEvt);
        }
    };
    itsNatDoc.addEventListener(listener);
}

public SPIState changeState(String stateName,ItsNatEventDOMStateless itsNatEvt)
{
    SPIStateDescriptor stateDesc = config.getSPIStateDescriptor(stateName);
    if (stateDesc == null)
    {
        return changeState(config.getNotFoundStateName(),itsNatEvt);
    }

    // Cleaning previous state:
    if (!itsNatDoc.isLoading())
    {
        ClientDocument clientDoc = itsNatDoc.getClientDocumentOwner();
        String contentParentRef = clientDoc.getScriptUtil().getNodeReference(config.getContentParentElement());
        clientDoc.addCodeToSend("window.spiSite.removeChildren(" + contentParentRef + ");");  // ".innerHTML = '';"
    }

    // Setting new state:
    changeActiveMenu(stateName);

    String fragmentName = stateDesc.isMainLevel() ? stateName : getFirstLevelStateName(stateName);
    DocumentFragment frag = loadDocumentFragment(fragmentName);
    config.getContentParentElement().appendChild(frag);

    return createSPIState(stateDesc,itsNatEvt);
}

package org.itsnat.spistlesshashbang;

import org.itsnat.spi.SPIMainDocumentConfig;
import javax.servlet.http.HttpServletRequest;
import org.itsnat.core.http.ItsNatHttpServletRequest;
import org.itsnat.core.http.ItsNatHttpServletResponse;
import org.itsnat.spistless.SPIStlessMainDocument;

public abstract class SPIStlessHashbangMainDocument extends SPIStlessMainDocument
{
    public SPIStlessHashbangMainDocument(ItsNatHttpServletRequest request, ItsNatHttpServletResponse response,SPIMainDocumentConfig config)
    {
        super(request, response,config);

        if (!itsNatDoc.isCreatedByStatelessEvent())
        {
            HttpServletRequest servReq = request.getHttpServletRequest();
            String stateName = servReq.getParameter("_escaped_fragment_"); // Google bot, has priority, its value is based on the hash fragment
            if (stateName != null)
            {
                if (stateName.startsWith("st=")) // st means "state"
                    stateName = stateName.substring("st=".length(), stateName.length());
                else // Wrong format
                    stateName = config.getDefaultStateName();
            }
            else
            {
                stateName = servReq.getParameter("st");
                if (stateName == null)
                    stateName = config.getDefaultStateName();
            }

            changeState(stateName);
        }

    }
}

package org.itsnat.spistlesshashbangtut;

import org.itsnat.spistlesshashbang.SPIStlessHashbangMainDocument;
import org.itsnat.core.event.ItsNatEventDOMStateless;
import org.itsnat.core.http.ItsNatHttpServletRequest;
import org.itsnat.core.http.ItsNatHttpServletResponse;
import org.itsnat.spi.SPIMainDocumentConfig;
import org.itsnat.spi.SPIState;
import org.itsnat.spi.SPIStateDescriptor;
import org.w3c.dom.Element;

public class SPITutMainDocument extends SPIStlessHashbangMainDocument
{
    public SPITutMainDocument(ItsNatHttpServletRequest request, ItsNatHttpServletResponse response,SPIMainDocumentConfig config)
    {
        super(request,response,config);
    }

    @Override
    public SPIState changeState(String stateName,ItsNatEventDOMStateless itsNatEvt)
    {
        SPIState state = super.changeState(stateName,itsNatEvt);

        itsNatDoc.addCodeToSend("try{ window.scroll(0,-5000); }catch(ex){}");
        // try/catch is used to avoid exceptions when some (mobile) browser does not support window.scroll()

        return state;
    }

    @Override
    public SPIState createSPIState(SPIStateDescriptor stateDesc,ItsNatEventDOMStateless itsNatEvt)
    {
        String stateName = stateDesc.getStateName();
        if (stateName.equals("overview")||stateName.equals("overview.popup"))
        {
            boolean popup = false;
            if (stateName.equals("overview.popup"))
            {
                popup = true;
                stateDesc = getSPIStateDescriptor("overview");
            }
            return new SPITutStateOverview(this,stateDesc,popup);
        }
        else if (stateName.equals("detail"))
        {
            String stateSecondaryName = itsNatEvt != null? (String)itsNatEvt.getExtraParam("state_secondary_name") : null;
            return new SPITutStateDetail(this,stateDesc,stateSecondaryName);
        }
        else
            return null;
    }

    @Override
    public void onChangeActiveMenu(Element menuItemElem,boolean active)
    {
        if (active)
        {
            menuItemElem.setAttribute("class","menuOpSelected");
        }
        else
        {
            menuItemElem.setAttribute("class","foo");
            menuItemElem.removeAttribute("class");
        }
    }
}

...
else if (stateName.equals("detail"))
{
    String stateSecondaryName = itsNatEvt != null? (String)itsNatEvt.getExtraParam("state_secondary_name") : null;
    return new SPITutStateDetail(this,stateDesc,stateSecondaryName);
}
...

<a itsnat:nocache="true" id="detailMoreId" href="javascript:;" onclick="setState('detail',this.getAttribute('action')); return false;">Hide|More Detail</a><br>

@Override
public void onChangeActiveMenu(Element menuItemElem,boolean active)
{
    if (active)
    {
        menuItemElem.setAttribute("class","menuOpSelected");
    }
    else
    {
        menuItemElem.setAttribute("class","foo");
        menuItemElem.removeAttribute("class");
    }
}

package org.itsnat.spistlesshashbangtut;

import org.itsnat.core.ClientDocument;
import org.itsnat.core.domutil.ItsNatTreeWalker;
import org.itsnat.spi.SPIState;
import org.itsnat.spi.SPIStateDescriptor;
import org.w3c.dom.DocumentFragment;
import org.w3c.dom.Element;
import org.w3c.dom.html.HTMLDocument;

public class SPITutStateDetail extends SPIState
{
    public SPITutStateDetail(SPITutMainDocument spiTutDoc,SPIStateDescriptor stateDesc,String stateSecondaryName)
    {
        super(spiTutDoc,stateDesc,true);

        HTMLDocument doc = getItsNatHTMLDocument().getHTMLDocument();
        Element detailMoreLink = doc.getElementById("detailMoreId");

        if ("moreDetail".equals(stateSecondaryName))
        {
            DocumentFragment frag = spiTutDoc.loadDocumentFragment("detail.more");
            Element detailMoreElem = ItsNatTreeWalker.getFirstChildElement(frag);
            detailMoreElem.setAttribute("id", "detailContentId");

            Element contentParentElem = spiTutDoc.getContentParentElement();
            contentParentElem.appendChild(detailMoreElem);
            detailMoreLink.setTextContent("Hide");
            detailMoreLink.setAttribute("action","lessDetail");
        }
        else
        {
            ClientDocument clientDoc = getItsNatHTMLDocument().getClientDocumentOwner();
            clientDoc.addCodeToSend("removeById('detailContentId');");

            detailMoreLink.setTextContent("More Detail");
            detailMoreLink.setAttribute("action","moreDetail");
        }
    }
}

ClientDocument clientDoc = getItsNatHTMLDocument().getClientDocumentOwner();
clientDoc.addCodeToSend("removeById('detailContentId');");

package org.itsnat.spistlesshashbangtut;

import org.itsnat.spi.SPIState;
import org.itsnat.spi.SPIStateDescriptor;

public class SPITutStateOverview extends SPIState
{
    public SPITutStateOverview(SPITutMainDocument spiTutDoc,SPIStateDescriptor stateDesc,boolean showPopup)
    {
        super(spiTutDoc,stateDesc,!showPopup);

        if (showPopup) showOverviewPopup();
        else cleanOverviewPopup();
    }

    public void showOverviewPopup()
    {
        new SPITutStateOverviewPopup(this);
    }

    public void cleanOverviewPopup()
    {
        SPITutStateOverviewPopup.dispose(this);
    }

}

package org.itsnat.spistlesshashbangtut;

import org.itsnat.comp.ItsNatComponentManager;
import org.itsnat.comp.layer.ItsNatModalLayer;
import org.itsnat.core.ClientDocument;
import org.itsnat.core.domutil.ItsNatTreeWalker;
import org.itsnat.core.html.ItsNatHTMLDocument;
import org.itsnat.spi.SPIMainDocument;
import org.itsnat.spi.SPIState;
import org.itsnat.spi.SPIStateDescriptor;
import org.w3c.dom.DocumentFragment;
import org.w3c.dom.Element;
import org.w3c.dom.html.HTMLBodyElement;
import org.w3c.dom.html.HTMLDocument;

public class SPITutStateOverviewPopup extends SPIState
{
    protected SPITutStateOverview parent;
    protected ItsNatModalLayer layer;

    public SPITutStateOverviewPopup(SPITutStateOverview parent)
    {
        this(parent,parent.getSPIMainDocument().getSPIStateDescriptor("overview.popup"));
    }

    public SPITutStateOverviewPopup(SPITutStateOverview parent,SPIStateDescriptor stateDesc)
    {
        super(parent.getSPIMainDocument(),stateDesc,true);
        this.parent = parent;

        SPIMainDocument spiTutDoc = getSPIMainDocument();
        ItsNatHTMLDocument itsNatDoc = getItsNatHTMLDocument();
        HTMLDocument doc = itsNatDoc.getHTMLDocument();
        ItsNatComponentManager compMgr = itsNatDoc.getItsNatComponentManager();
        ItsNatModalLayer layer = compMgr.createItsNatModalLayer(null,false,1,0.5f,"black",null);
        Element parentLayer = layer.getElement();
        parentLayer.setAttribute("id","overviewPopupLayerContainerId");

        HTMLBodyElement body = (HTMLBodyElement)doc.getBody();

        DocumentFragment frag = spiTutDoc.loadDocumentFragment("overview.popup");
        Element container = ItsNatTreeWalker.getFirstChildElement(frag);
        body.appendChild(container);

        container.setAttribute("id","overviewPopupContentContainerId");

        itsNatDoc.addCodeToSend("try{ window.scroll(0,-1000); }catch(ex){}");
        // try/catch is used to prevent some mobile browser does not support it
    }

    public static void dispose(SPITutStateOverview parent)
    {
        ClientDocument clientDoc = parent.getItsNatHTMLDocument().getClientDocumentOwner();
        clientDoc.addCodeToSend("removeById('overviewPopupLayerContainerId');");
        clientDoc.addCodeToSend("removeById('overviewPopupContentContainerId');");
    }
}