/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.wicket.request.handler;
import org.apache.wicket.Application;
import org.apache.wicket.Session;
import org.apache.wicket.page.IPageManager;
import org.apache.wicket.protocol.http.PageExpiredException;
import org.apache.wicket.request.IRequestHandler;
import org.apache.wicket.request.IRequestMapper;
import org.apache.wicket.request.component.IRequestablePage;
import org.apache.wicket.request.mapper.IPageSource;
import org.apache.wicket.request.mapper.StalePageException;
import org.apache.wicket.request.mapper.parameter.PageParameters;
import org.apache.wicket.util.lang.Args;
/**
* Provides page instance for request handlers. Each of the constructors has just enough information
* to get existing or create new page instance. Requesting or creating page instance is deferred
* until {@link #getPageInstance()} is called.
* <p>
* Purpose of this class is to reduce complexity of both {@link IRequestMapper}s and
* {@link IRequestHandler}s. {@link IRequestMapper} examines the URL, gathers all relevant
* information about the page in the URL (combination of page id, page class, page parameters and
* render count), creates {@link PageProvider} object and creates a {@link IRequestHandler} instance
* that can use the {@link PageProvider} to access the page.
* <p>
* Apart from simplifying {@link IRequestMapper}s and {@link IRequestHandler}s {@link PageProvider}
* also helps performance because creating or obtaining page from {@link IPageManager} is delayed
* until the {@link IRequestHandler} actually requires the page.
*
* @author Matej Knopp
*/
public class PageProvider implements IPageProvider
{
private Integer renderCount;
private IPageSource pageSource;
private IRequestablePage pageInstance;
private Class<? extends IRequestablePage> pageClass;
private Integer pageId;
private PageParameters pageParameters;
/**
* Creates a new page provider object. Upon calling of {@link #getPageInstance()} this provider
* will return page instance with specified id.
*
* @param pageId
* @param renderCount
* optional argument
*/
public PageProvider(final int pageId, final Integer renderCount)
{
this.pageId = pageId;
this.renderCount = renderCount;
}
/**
* Creates a new page provider object. Upon calling of {@link #getPageInstance()} this provider
* will return page instance with specified id if it exists and it's class matches pageClass. If
* none of these is true new page instance will be created.
*
* @param pageId
* @param pageClass
* @param renderCount
* optional argument
*/
public PageProvider(final int pageId, final Class<? extends IRequestablePage> pageClass,
Integer renderCount)
{
this(pageId, pageClass, new PageParameters(), renderCount);
}
/**
* Creates a new page provider object. Upon calling of {@link #getPageInstance()} this provider
* will return page instance with specified id if it exists and it's class matches pageClass. If
* none of these is true new page instance will be created.
*
* @param pageId
* @param pageClass
* @param pageParameters
* @param renderCount
* optional argument
*/
public PageProvider(final int pageId, final Class<? extends IRequestablePage> pageClass,
final PageParameters pageParameters, final Integer renderCount)
{
this.pageId = pageId;
setPageClass(pageClass);
setPageParameters(pageParameters);
this.renderCount = renderCount;
}
/**
* Creates a new page provider object. Upon calling of {@link #getPageInstance()} this provider
* will return new instance of page with specified class.
*
* @param pageClass
* @param pageParameters
*/
public PageProvider(final Class<? extends IRequestablePage> pageClass,
final PageParameters pageParameters)
{
setPageClass(pageClass);
if (pageParameters != null)
{
setPageParameters(pageParameters);
}
}
/**
* Creates a new page provider object. Upon calling of {@link #getPageInstance()} this provider
* will return new instance of page with specified class.
*
* @param pageClass
*/
public PageProvider(Class<? extends IRequestablePage> pageClass)
{
this(pageClass, null);
}
/**
* Creates a new page provider object. Upon calling of {@link #getPageInstance()} this provider
* will return the given page instance.
*
* @param page
*/
public PageProvider(IRequestablePage page)
{
Args.notNull(page, "page");
pageInstance = page;
}
/**
* @see org.apache.wicket.request.handler.IPageProvider#getPageInstance()
*/
public IRequestablePage getPageInstance()
{
if (pageInstance == null)
{
pageInstance = getPageInstance(pageId, pageClass, pageParameters, renderCount);
if (pageInstance == null)
{
throw new PageExpiredException("Page expired.");
}
touchPageInstance(pageInstance);
}
return pageInstance;
}
/**
* Mark the error page as candidate for storing
*
* @param page
* the page to store
*/
private void touchPageInstance(IRequestablePage page)
{
if (Session.exists())
{
Session.get().getPageManager().touchPage(page);
}
}
/**
* @see org.apache.wicket.request.handler.IPageProvider#getPageParameters()
*/
public PageParameters getPageParameters()
{
if (pageParameters != null)
{
return pageParameters;
}
else if (pageInstance != null)
{
return pageInstance.getPageParameters();
}
else
{
return null;
}
}
public boolean isNewPageInstance()
{
return pageInstance == null && pageId == null;
}
/**
* @see org.apache.wicket.request.handler.IPageProvider#getPageClass()
*/
public Class<? extends IRequestablePage> getPageClass()
{
if (pageClass != null)
{
return pageClass;
}
else
{
return getPageInstance().getClass();
}
}
protected IPageSource getPageSource()
{
if (pageSource != null)
{
return pageSource;
}
if (Application.exists())
{
return Application.get().getMapperContext();
}
else
{
throw new IllegalStateException(
"No application is bound to current thread. Call setPageSource() to manually assign pageSource to this provider.");
}
}
private IRequestablePage getPageInstance(Integer pageId,
Class<? extends IRequestablePage> pageClass, PageParameters pageParameters,
Integer renderCount)
{
IRequestablePage page = null;
boolean freshCreated = false;
if (pageId != null)
{
page = getPageSource().getPageInstance(pageId);
if (page != null && pageClass != null && page.getClass().equals(pageClass) == false)
{
page = null;
}
else if (page != null && pageParameters != null)
{
page.getPageParameters().overwriteWith(pageParameters);
}
}
if (page == null)
{
if (pageClass != null)
{
page = getPageSource().newPageInstance(pageClass, pageParameters);
freshCreated = true;
}
}
if (page != null && !freshCreated)
{
if (renderCount != null && page.getRenderCount() != renderCount)
{
throw new StalePageException(page);
}
}
return page;
}
/**
* Detaches the page if it has been loaded (that means either
* {@link #PageProvider(IRequestablePage)} constructor has been used or
* {@link #getPageInstance()} has been called).
*/
public void detach()
{
if (pageInstance != null)
{
pageInstance.detach();
}
}
/**
* If the {@link PageProvider} is used outside request thread (thread that does not have
* application instance assigned) it is necessary to specify a {@link IPageSource} instance so
* that {@link PageProvider} knows how to get a page instance.
*
* @param pageSource
*/
public void setPageSource(IPageSource pageSource)
{
this.pageSource = pageSource;
}
/**
*
* @param pageClass
*/
private void setPageClass(Class<? extends IRequestablePage> pageClass)
{
Args.notNull(pageClass, "pageClass");
this.pageClass = pageClass;
}
/**
*
* @param pageParameters
*/
private void setPageParameters(PageParameters pageParameters)
{
this.pageParameters = pageParameters;
}
/**
*
* @return page id
*/
public Integer getPageId()
{
return pageId;
}
}