javax.faces.application.ViewHandler Maven / Gradle / Ivy
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* to you under the Apache License, Version 2.0 (the
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*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
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*/
package javax.faces.application;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import javax.faces.FacesException;
import javax.faces.component.UIViewRoot;
import javax.faces.context.ExternalContext;
import javax.faces.context.FacesContext;
import javax.faces.view.ViewDeclarationLanguage;
import org.apache.myfaces.buildtools.maven2.plugin.builder.annotation.JSFWebConfigParam;
/**
* A ViewHandler manages the component-tree-creation and component-tree-rendering parts of a request lifecycle (ie
* "create view", "restore view" and "render response").
*
* A ViewHandler is responsible for generating the component tree when a new view is requested; see method "createView".
*
* When the user performs a "postback", ie activates a UICommand component within a view, then the ViewHandler is
* responsible for recreating a view tree identical to the one used previously to render that view; see method
* "restoreView".
*
* And the ViewHandler is also responsible for rendering the final output to be sent to the user by invoking the
* rendering methods on components; see method "renderView".
*
* This class also isolates callers from the underlying request/response system. In particular, this class does not
* explicitly depend upon the javax.servlet apis. This allows JSF to be used on servers that do not implement the
* servlet API (for example, plain CGI).
*
* Examples:
*
* - A JSP ViewHandler exists for using "jsp" pages as the presentation technology. This class then works together
* with a taghandler class and a jsp servlet class to implement the methods on this abstract class definition.
*
- A Facelets ViewHandler instead uses an xml file to define the components and non-component data that make up a
* specific view.
*
* Of course there is no reason why the "template" needs to be a textual file. A view could be generated based on data
* in a database, or many other mechanisms.
*
* This class is expected to be invoked via the concrete implementation of {@link javax.faces.lifecycle.Lifecycle}.
*
* For the official specification for this class, see JSF Specification.
*
* @author Manfred Geiler (latest modification by $Author: bommel $)
* @version $Revision: 1187700 $ $Date: 2011-10-22 07:19:37 -0500 (Sat, 22 Oct 2011) $
*/
public abstract class ViewHandler
{
public static final String CHARACTER_ENCODING_KEY = "javax.faces.request.charset";
public static final String DEFAULT_FACELETS_SUFFIX = ".xhtml";
public static final String DEFAULT_SUFFIX = ".xhtml .jsp";
/**
* Indicate the default suffixes, separated by spaces to derive the default file URI
* used by JSF to create views and render pages.
*/
@JSFWebConfigParam(defaultValue=".xhtml .jsp", since="1.1", group="viewhandler")
public static final String DEFAULT_SUFFIX_PARAM_NAME = "javax.faces.DEFAULT_SUFFIX";
/**
* The default extension used to handle facelets pages.
*/
@JSFWebConfigParam(defaultValue=".xhtml", since="2.0", group="viewhandler")
public static final String FACELETS_SUFFIX_PARAM_NAME = "javax.faces.FACELETS_SUFFIX";
/**
* Set of extensions handled by facelets, separated by ';'.
*/
@JSFWebConfigParam(since="2.0", group="viewhandler")
public static final String FACELETS_VIEW_MAPPINGS_PARAM_NAME = "javax.faces.FACELETS_VIEW_MAPPINGS";
// TODO: Notify EG on that last constant. Using the Facelets' param as well for backward compatiblity is
// silly. If an application uses Facelets then they'll be using facelets.jar. Once they chose to
// remove that JAR, they ought to be aware that some changes could be needed, like fixing their
// context-param. -= Simon Lessard =-
/**
* @since JSF 1.2
*/
public String calculateCharacterEncoding(FacesContext context)
{
String _encoding = null;
ExternalContext externalContext = context.getExternalContext();
String _contentType = externalContext.getRequestHeaderMap().get("Content-Type");
int _indexOf = _contentType == null ? -1 : _contentType.indexOf("charset");
if (_indexOf != -1)
{
String _tempEnc = _contentType.substring(_indexOf); // charset=UTF-8
_encoding = _tempEnc.substring(_tempEnc.indexOf("=") + 1); // UTF-8
if (_encoding.length() == 0)
{
_encoding = null;
}
}
if (_encoding == null)
{
boolean _sessionAvailable = externalContext.getSession(false) != null;
if (_sessionAvailable)
{
Object _sessionParam = externalContext.getSessionMap().get(CHARACTER_ENCODING_KEY);
if (_sessionParam != null)
{
_encoding = _sessionParam.toString();
}
}
}
return _encoding;
}
/**
* Return the Locale object that should be used when rendering this view to the current user.
*
* Some request protocols allow an application user to specify what locale they prefer the response to be in. For
* example, HTTP requests can specify the "accept-language" header.
*
* Method {@link javax.faces.application.Application#getSupportedLocales()} defines what locales this JSF
* application is capable of supporting.
*
* This method should match such sources of data up and return the Locale object that is the best choice for
* rendering the current application to the current user.
*/
public abstract Locale calculateLocale(FacesContext context);
/**
* Return the id of an available render-kit that should be used to map the JSF components into user presentation.
*
* The render-kit selected (eg html, xhtml, pdf, xul, ...) may depend upon the user, properties associated with the
* request, etc.
*/
public abstract String calculateRenderKitId(FacesContext context);
/**
* Build a root node for a component tree.
*
* When a request is received, this method is called if restoreView returns null, ie this is not a "postback". In
* this case, a root node is created and then renderView is invoked. It is the responsibility of the renderView
* method to build the full component tree (ie populate the UIViewRoot with descendant nodes).
*
* This method is also invoked when navigation occurs from one view to another, where the viewId passed is the id of
* the new view to be displayed. Again it is the responsibility of renderView to then populate the viewroot with
* descendants.
*
* The locale and renderKit settings are inherited from the current UIViewRoot that is configured before this method
* is called. That means of course that they do NOT get set for GET requests, including navigation that has the
* redirect flag set.
*/
public abstract UIViewRoot createView(FacesContext context, String viewId);
/**
* @param context
* @param input
* @return
*
* @since 2.0
*/
public String deriveViewId(FacesContext context, String input)
{
//The default implementation of this method simply returns rawViewId unchanged.
return input;
}
/**
* Returns a URL, suitable for encoding and rendering, that (if activated) will cause the JSF request processing lifecycle for the specified viewId to be executed
*/
public abstract String getActionURL(FacesContext context, String viewId);
/**
* Return a JSF action URL derived from the viewId argument that is suitable to be used as the target of a link in a JSF response. Compiliant implementations must implement this method as specified in section JSF.7.5.2. The default implementation simply calls through to getActionURL(javax.faces.context.FacesContext, java.lang.String), passing the arguments context and viewId.
*
* @param context
* @param viewId
* @param parameters
* @param includeViewParams
* @return
*
* @since 2.0
*/
public String getBookmarkableURL(FacesContext context, String viewId, Map> parameters,
boolean includeViewParams)
{
return getActionURL(context, viewId);
}
/**
* Return the ViewDeclarationLanguage instance used for this ViewHandler instance.
*
* The default implementation of this method returns null.
*
* @param context
* @param viewId
* @return
*
* @since 2.0
*/
public ViewDeclarationLanguage getViewDeclarationLanguage(FacesContext context, String viewId)
{
// TODO: In some places like RestoreViewExecutor, we are calling deriveViewId after call restoreViewSupport.calculateViewId
// Maybe this method should be called from here, because it is supposed that calculateViewId "calculates the view id!"
// here we return null to support pre jsf 2.0 ViewHandlers (e.g. com.sun.facelets.FaceletViewHandler),
// because they don't provide any ViewDeclarationLanguage,
// but in the default implementation (ViewHandlerImpl) we return vdlFactory.getViewDeclarationLanguage(viewId)
return null;
}
/**
* Return a JSF action URL derived from the viewId argument that is suitable to be used by the NavigationHandler to issue a redirect request to the URL using a NonFaces request. Compiliant implementations must implement this method as specified in section JSF.7.5.2. The default implementation simply calls through to getActionURL(javax.faces.context.FacesContext, java.lang.String), passing the arguments context and viewId.
*
* @param context
* @param viewId
* @param parameters
* @param includeViewParams
* @return
*
* @since 2.0
*/
public String getRedirectURL(FacesContext context, String viewId, Map> parameters,
boolean includeViewParams)
{
return getActionURL(context, viewId);
}
/**
* Returns a URL, suitable for encoding and rendering, that (if activated) will retrieve the specified web application resource.
*/
public abstract String getResourceURL(FacesContext context, String path);
/**
* Initialize the view for the request processing lifecycle.
*
* This method must be called at the beginning of the Restore View Phase of the Request Processing Lifecycle. It is responsible for performing any per-request initialization necessary to the operation of the lifycecle.
*
* The default implementation must perform the following actions. If ExternalContext.getRequestCharacterEncoding() returns null, call calculateCharacterEncoding(javax.faces.context.FacesContext) and pass the result, if non-null, into the ExternalContext.setRequestCharacterEncoding(java.lang.String) method. If ExternalContext.getRequestCharacterEncoding() returns non-null take no action.
*
* @since JSF 1.2
*/
public void initView(FacesContext context) throws FacesException
{
String _encoding = this.calculateCharacterEncoding(context);
if (_encoding != null)
{
try
{
context.getExternalContext().setRequestCharacterEncoding(_encoding);
}
catch (UnsupportedEncodingException uee)
{
throw new FacesException(uee);
}
}
}
/**
* Perform whatever actions are required to render the response view to the response object associated with the current FacesContext.
*
* Otherwise, the default implementation must obtain a reference to the ViewDeclarationLanguage for the viewId of the argument viewToRender and call its ViewDeclarationLanguage.renderView(javax.faces.context.FacesContext, javax.faces.component.UIViewRoot) method, returning the result and not swallowing any exceptions thrown by that method.
*/
public abstract void renderView(FacesContext context, UIViewRoot viewToRender) throws IOException, FacesException;
/**
* Perform whatever actions are required to restore the view associated with the specified FacesContext and viewId. It may delegate to the restoreView of the associated StateManager to do the actual work of restoring the view. If there is no available state for the specified viewId, return null.
*
* Otherwise, the default implementation must obtain a reference to the ViewDeclarationLanguage for this viewId and call its ViewDeclarationLanguage.restoreView(javax.faces.context.FacesContext, java.lang.String) method, returning the result and not swallowing any exceptions thrown by that method.
*/
public abstract UIViewRoot restoreView(FacesContext context, String viewId);
/**
* Take any appropriate action to either immediately write out the current state information (by calling StateManager.writeState(javax.faces.context.FacesContext, java.lang.Object), or noting where state information should later be written.
*
* This method must do nothing if the current request is an Ajax request. When responding to Ajax requests, the state is obtained by calling StateManager.getViewState(javax.faces.context.FacesContext) and then written into the Ajax response during final encoding (UIViewRoot.encodeEnd(javax.faces.context.FacesContext).
*/
public abstract void writeState(FacesContext context) throws IOException;
}