public abstract class ViewHandler extends Object
ViewHandler is the pluggablity mechanism for allowing implementations of or applications using the JJakarta Server Faces specification to provide their own handling of the activities in the Render Response and Restore View phases of the request processing lifecycle. This allows for implementations to support different response generation technologies, as well as alternative strategies for saving and restoring the state of each view. An implementation of this class must be thread-safe.
Please see StateManager
for information on how the ViewHandler
interacts the
StateManager
.
Version 2 of the specification formally introduced the concept of View Declaration
Language. A View Declaration Language (VDL) is a syntax used to declare user interfaces
comprised of instances of Jakarta Server Faces UIComponent
s. Any of the responsibilities of the
ViewHandler
that specifically deal with the VDL sub-system are now the domain of the
VDL implementation. These responsibilities are defined on the ViewDeclarationLanguage
class. The ViewHandler
provides getViewDeclarationLanguage(javax.faces.context.FacesContext, java.lang.String)
as a convenience
method to access the VDL implementation given a viewId
.
Modifier and Type | Field and Description |
---|---|
static String |
CHARACTER_ENCODING_KEY
The key, in the session's attribute set, under which the response character encoding may be
stored and retrieved.
|
static String |
DEFAULT_FACELETS_SUFFIX
The value to use for the default extension for Facelet based XHTML pages if the webapp is using url extension mapping. |
static String |
DEFAULT_SUFFIX
The value to use for the default extension if the webapp is using url extension mapping. |
static String |
DEFAULT_SUFFIX_PARAM_NAME
Allow the web application to define a
list of alternate suffixes for pages containing Jakarta Server Faces
content.
|
static String |
DISABLE_FACELET_JSF_VIEWHANDLER_PARAM_NAME
If this param is set, and calling toLowerCase().equals("true") on a String representation of its value returns true, the default ViewHandler must behave as specified in the latest 1.2 version of this specification. |
static String |
FACELETS_BUFFER_SIZE_PARAM_NAME
The buffer size to set on the response when the ResponseWriter is generated. |
static String |
FACELETS_DECORATORS_PARAM_NAME
A semicolon (;) delimitted list of class names of type javax.faces.view.facelets.TagDecorator, with a no-argument constructor. |
static String |
FACELETS_LIBRARIES_PARAM_NAME
If this param is set, the runtime must interpret it as a semicolon (;) separated list of paths, starting with "/" (without the quotes). |
static String |
FACELETS_REFRESH_PERIOD_PARAM_NAME
When a page is requested, what interval in seconds should the compiler check for changes. |
static String |
FACELETS_SKIP_COMMENTS_PARAM_NAME
If this param is set, and calling toLowerCase().equals("true") on a String representation of its value returns true, the runtime must ensure that any XML comments in the Facelets source page are not delivered to the client. |
static String |
FACELETS_SUFFIX_PARAM_NAME
Allow the web application to define an alternate suffix for Facelet based XHTML pages containing Jakarta Server Faces content. |
static String |
FACELETS_VIEW_MAPPINGS_PARAM_NAME
Allow the web application to define a semicolon (;) separated list of strings that is used to forcibly declare that certain pages in the application must be interpreted as using Facelets, regardless of their extension. |
Constructor and Description |
---|
ViewHandler() |
Modifier and Type | Method and Description |
---|---|
void |
addProtectedView(String urlPattern)
Add the argument |
String |
calculateCharacterEncoding(FacesContext context)
Returns the correct character encoding to be used for this request.
|
abstract Locale |
calculateLocale(FacesContext context)
Returns an appropriate
Locale to use for this and subsequent requests for the current
client. |
abstract String |
calculateRenderKitId(FacesContext context)
Return an appropriate
renderKitId for this and subsequent requests from the
current client. |
abstract UIViewRoot |
createView(FacesContext context,
String viewId)
Create and return a new
UIViewRoot
instance initialized with information from the argument FacesContext and
viewId . |
String |
deriveLogicalViewId(FacesContext context,
String requestViewId)
Derive and return the viewId from the current request, or the argument input by following the algorithm defined in specification section JSF.7.6.2. |
String |
deriveViewId(FacesContext context,
String requestViewId)
Derive and return the viewId from the current request, or the argument input by following the algorithm defined in specification section JSF.7.6.2. |
abstract String |
getActionURL(FacesContext context,
String viewId)
If the value returned from this method is used as
the |
String |
getBookmarkableURL(FacesContext context,
String viewId,
Map<String,List<String>> parameters,
boolean includeViewParams)
Return a Jakarta Server Faces action URL derived from the viewId argument that is suitable to be used as the target of a link in a Jakarta Server Faces response. |
Set<String> |
getProtectedViewsUnmodifiable()
Return an unmodifiable |
String |
getRedirectURL(FacesContext context,
String viewId,
Map<String,List<String>> parameters,
boolean includeViewParams)
Return a Jakarta Server Faces action URL derived from the |
abstract String |
getResourceURL(FacesContext context,
String path)
If the value returned from this method is used as the |
ViewDeclarationLanguage |
getViewDeclarationLanguage(FacesContext context,
String viewId)
Return the |
Stream<String> |
getViews(FacesContext facesContext,
String path,
int maxDepth,
ViewVisitOption... options)
Return a |
Stream<String> |
getViews(FacesContext facesContext,
String path,
ViewVisitOption... options)
Return a |
abstract String |
getWebsocketURL(FacesContext context,
String channel)
If the value returned from this method is used as the |
void |
initView(FacesContext context)
Initialize the view for the request processing
lifecycle.
|
boolean |
removeProtectedView(String urlPattern)
Remove the argument |
abstract void |
renderView(FacesContext context,
UIViewRoot viewToRender)
Perform whatever actions are required to render the
response view to the response object associated with the current
FacesContext . |
abstract UIViewRoot |
restoreView(FacesContext context,
String viewId)
Perform whatever actions are required to restore
the view associated with the specified
FacesContext and viewId . |
abstract void |
writeState(FacesContext context)
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. |
public static final String CHARACTER_ENCODING_KEY
The key, in the session's attribute set, under which the response character encoding may be stored and retrieved.
public static final String DEFAULT_SUFFIX_PARAM_NAME
Allow the web application to define a
list of alternate suffixes for pages containing Jakarta Server Faces
content. This list is a space separated list of values of
the form .<extension>
. The first physical resource whose extension
matches one of the configured extensions will be the suffix used to create the view
ID. If this init parameter is not specified, the default value is taken from the value
of the constant DEFAULT_SUFFIX
.
public static final String DEFAULT_SUFFIX
The value to use for the default extension if the webapp is using url extension mapping.
public static final String FACELETS_SKIP_COMMENTS_PARAM_NAME
If this param is set, and calling toLowerCase().equals("true") on a String representation of its value returns true, the runtime must ensure that any XML comments in the Facelets source page are not delivered to the client. The runtime must also consider the facelets.SKIP_COMMENTS param name as an alias to this param name for backwards compatibility with existing facelets tag libraries.
public static final String FACELETS_SUFFIX_PARAM_NAME
Allow the web application to define an alternate suffix for Facelet based XHTML pages
containing Jakarta Server Faces content. If this init parameter is not specified, the default value is taken
from the value of the constant DEFAULT_FACELETS_SUFFIX
public static final String DEFAULT_FACELETS_SUFFIX
The value to use for the default extension for Facelet based XHTML pages if the webapp is using url extension mapping.
public static final String FACELETS_VIEW_MAPPINGS_PARAM_NAME
Allow the web application to define a semicolon (;) separated list of strings that is used to
forcibly declare that certain pages in the application must be interpreted as using Facelets,
regardless of their extension. Each entry in the semicolon (;) separated list of strings is
either a file extension, as in *.xhtml
, or a resource prefix (starting with '/'
and interpreted as relative to the web application root), as in /user/*
. The
latter class of entry can also take the form of
/<filename>.<extension>*
such as /login.jsp*
. The
runtime must also consider the facelets.VIEW_MAPPINGS
param name as an alias to
this param name for backwards compatibility with existing Facelets applications.
public static final String FACELETS_BUFFER_SIZE_PARAM_NAME
The buffer size to set on the response when the ResponseWriter is generated. By default the value is 1024. A value of -1 will not assign a buffer size on the response. This should be increased if you are using development mode in order to guarantee that the response isn't partially rendered when an error is generated. The runtime must also consider the facelets.BUFFER_SIZE param name as an alias to this param name for backwards compatibility with existing facelets tag libraries.
public static final String FACELETS_REFRESH_PERIOD_PARAM_NAME
When a page is requested, what interval in seconds
should the compiler check for changes. If you don't want the compiler to check for changes
once the page is compiled, then use a value of -1. Setting a low refresh period helps during
development to be able to edit pages in a running application.The runtime must also consider
the facelets.REFRESH_PERIOD param name as an alias to this param name for backwards
compatibility with existing facelets tag libraries. If
ProjectStage
is set to Production
and this value is
not otherwise specified, the runtime must act as if it is set to -1.
public static final String FACELETS_LIBRARIES_PARAM_NAME
If this param is set, the runtime must interpret it as a semicolon (;) separated list of paths, starting with "/" (without the quotes). The runtime must interpret each entry in the list as a path relative to the web application root and interpret the file found at that path as a facelet tag library, conforming to the facelet taglibrary schema and expose the tags therein according to Section "Facelet Tag Library mechanism". The runtime must also consider the facelets.LIBRARIES param name as an alias to this param name for backwards compatibility with existing facelets tag libraries.
public static final String FACELETS_DECORATORS_PARAM_NAME
A semicolon (;) delimitted list of class names of type javax.faces.view.facelets.TagDecorator, with a no-argument constructor. These decorators will be loaded when the first request for a Facelets VDL view hits the ViewHandler for page compilation.The runtime must also consider the facelets.DECORATORS param name as an alias to this param name for backwards compatibility with existing facelets tag libraries.
public static final String DISABLE_FACELET_JSF_VIEWHANDLER_PARAM_NAME
If this param is set, and calling toLowerCase().equals("true") on a String representation of its value returns true, the default ViewHandler must behave as specified in the latest 1.2 version of this specification. Any behavior specified in Section "Default ViewDeclarationLanguage Implementation" of the spec prose document and implemented in the default ViewHandler that pertains to handling requests for pages authored in the Jakarta Server Faces View Declaration Language must not be executed by the runtime.
public void initView(FacesContext context) throws FacesException
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.
context
- the Faces context.FacesException
- if a problem occurs setting the encoding, such as the
UnsupportedEncodingException
thrown by the underlying Jakarta Servlet or
Portlet technology when the encoding is not supported.public abstract UIViewRoot restoreView(FacesContext context, String viewId)
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.
context
- FacesContext
for the current requestviewId
- the view identifier for the current requestNullPointerException
- if context
is null
FacesException
- if a Jakarta Servlet error occurspublic abstract UIViewRoot createView(FacesContext context, String viewId)
Create and return a new UIViewRoot
instance initialized with information from the argument FacesContext
and
viewId
. Locate the
ViewDeclarationLanguage
implementation for the VDL used in the view. The argument
viewId
must be converted to a physical viewId
that can refer to an
actual resource suitable for use by the ViewDeclarationLanguage
ViewDeclarationLanguage.createView(javax.faces.context.FacesContext, java.lang.String)
, which must be called by this method.
context
- the Faces context.viewId
- the view id.NullPointerException
- if context
is null
public abstract void renderView(FacesContext context, UIViewRoot viewToRender) throws IOException, FacesException
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.
context
- FacesContext
for the current requestviewToRender
- the view to renderIOException
- if an input/output error occursNullPointerException
- if context
or viewToRender
is
null
FacesException
- if a Jakarta Servlet error occurspublic abstract Locale calculateLocale(FacesContext context)
Returns an appropriate Locale
to use for this and subsequent requests for the current
client.
context
- FacesContext
for the current requestNullPointerException
- if context
is null
public String calculateCharacterEncoding(FacesContext context)
Returns the correct character encoding to be used for this request.
The following algorithm is employed.
Examine the Content-Type
request header. If it has a charset
parameter, extract it and return that as the encoding.
If no charset
parameter was found, check for the existence of a session by
calling ExternalContext.getSession(boolean)
passing false
as the
argument. If that method returns true
, get the session Map by calling
ExternalContext.getSessionMap()
and look for a value under the key given by the value
of the symbolic constant CHARACTER_ENCODING_KEY
. If present, return the
value, converted to String.
Otherwise, return null
context
- the Faces context.null
public abstract String calculateRenderKitId(FacesContext context)
Return an appropriate renderKitId
for this and subsequent requests from the
current client. It is an error for this method to return null
.
The default return value is
RenderKitFactory.HTML_BASIC_RENDER_KIT
.
context
- FacesContext
for the current requestNullPointerException
- if context
is null
public String deriveViewId(FacesContext context, String requestViewId)
Derive and return the viewId from the current request, or the argument input by following the algorithm defined in specification section JSF.7.6.2.
This method should work correctly when the FacesServlet is invoked via either a
path mapping
, extension mapping
or an exact match
(mapping) as defined by Servlet.12.2. Note that path mapping
is also commonly
known as prefix mapping (e.g. "/faces/*") and extension mapping
as suffix
mapping (e.g. "*.xhtml"). An exact match
is possible where there's a servlet
mapping with an exact URL pattern such as "/foo".
The default implementation of this method simply returns requestViewId unchanged.
context
- the FacesContext
for this requestrequestViewId
- the viewId
to derive,public String deriveLogicalViewId(FacesContext context, String requestViewId)
Derive and return the viewId from the current request, or the argument input by following the
algorithm defined in specification section JSF.7.6.2. Note that unlike
deriveViewId()
, this method does not require that a physical view be present.
This method should work correctly when the FacesServlet is invoked via either a
path mapping
, extension mapping
or an exact match
(mapping) as defined by Servlet.12.2. Note that path mapping
is also commonly
known as prefix mapping (e.g. "/faces/*") and extension mapping
as suffix
mapping (e.g. "*.xhtml"). An exact match
is possible where there's a servlet
mapping with an exact URL pattern such as "/foo".
The default implementation of this method simply returns requestViewId unchanged.
context
- the FacesContext
for this requestrequestViewId
- the viewId
to derive,public abstract String getActionURL(FacesContext context, String viewId)
If the value returned from this method is used as
the file
argument to the four-argument constructor for java.net.URL
(assuming appropriate values are used for the first three arguments), then a client making a
request to the toExternalForm()
of that URL
will select the
argument viewId
for traversing the Jakarta Server Faces lifecycle. Please see section JSF.7.6.2
for the complete specification, especially for details
related to view protection using the
ResponseStateManager.NON_POSTBACK_VIEW_TOKEN_PARAM
and the behavior when the current request is to a URL
for which the FacesServlet has an exact mapping as defined by Servlet.12.2.
context
- FacesContext
for this requestviewId
- View identifier of the desired viewIllegalArgumentException
- if viewId
is not valid for this
ViewHandler
, or does not start with "/".NullPointerException
- if context
or viewId
is
null
.public String getRedirectURL(FacesContext context, String viewId, Map<String,List<String>> parameters, boolean includeViewParams)
Return a Jakarta Server Faces 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. Compliant implementations must implement this method as specified in section
JSF.7.6.2. The default implementation simply calls through to getActionURL(javax.faces.context.FacesContext, java.lang.String)
, passing
the arguments context
and viewId
.
context
- The FacesContext processing this requestviewId
- The view identifier of the target pageparameters
- A mapping of parameter names to one or more valuesincludeViewParams
- A flag indicating whether view parameters should be encoded into
this URLpublic String getBookmarkableURL(FacesContext context, String viewId, Map<String,List<String>> parameters, boolean includeViewParams)
Return a Jakarta Server Faces action URL derived from the viewId argument that is suitable to be used as the
target of a link in a Jakarta Server Faces response. Compliant implementations must implement this method as
specified in section JSF.7.6.2. The default implementation simply calls through to
getActionURL(javax.faces.context.FacesContext, java.lang.String)
, passing the arguments context
and viewId
.
context
- The FacesContext processing this requestviewId
- The view identifier of the target pageparameters
- A mapping of parameter names to one or more valuesincludeViewParams
- A flag indicating whether view parameters should be encoded into
this URLpublic abstract String getResourceURL(FacesContext context, String path)
If the value returned from this method is used as the file
argument to the
four-argument constructor for java.net.URL
(assuming appropriate values are used
for the first three arguments), then a client making a request to the
toExternalForm()
of that URL
will select the argument
path
for direct rendering. If the specified path starts with a slash, it must be
treated as context relative; otherwise, it must be treated as relative to the action URL of
the current view.
context
- FacesContext
for the current requestpath
- Resource path to convert to a URLIllegalArgumentException
- if viewId
is not valid for this
ViewHandler
.NullPointerException
- if context
or path
is
null
.public abstract String getWebsocketURL(FacesContext context, String channel)
If the value returned from this method is used as the file
argument to the
four-argument constructor for java.net.URL
(assuming appropriate values are used
for the first three arguments), then a client making a push handshake request to the
toExternalForm()
of that URL
will select the argument
channel
for connecting the websocket push channel in the current view. It must
match the PushContext.URI_PREFIX
of the endpoint.
context
- FacesContext
for the current request.channel
- The channel name of the websocket.NullPointerException
- if context
or channel
is
null
.PushContext.URI_PREFIX
public Set<String> getProtectedViewsUnmodifiable()
Return an unmodifiable Set
of the protected views currently known to this
ViewHandler
instance. Compliant implementations must return a Set
that is the concatenation of the contents of all the <url-pattern>
elements within all the <protected-views>
in all of the application
configuration resources in the current application. The runtime must support calling this
method at any time after application startup. The default implementation returns an
unmodifiable empty Set
.
public void addProtectedView(String urlPattern)
Add the argument urlPattern
to the thread safe Set
of protected
views for this application. Compliant implementations make it so a subsequent call to
getProtectedViewsUnmodifiable()
contains the argument. The runtime must support
calling this method at any time after application startup. The default implementation takes
no action.
urlPattern
- the url-pattern to add.public boolean removeProtectedView(String urlPattern)
Remove the argument urlPattern
from the thread safe Set
of
protected views for this application, if present in the Set
. If the argument
urlPattern
is not present in the Set
, this method has no effect.
Compliant implementations must make it so a subsequent call to
getProtectedViewsUnmodifiable()
does not contain the argument. The runtime must
support calling this method at any time after application startup. Returns true
if this Set
contained the argument. The default implementation takes no action
and returns false
.
urlPattern
- the url-pattern to remove.true
if in the Set
, false
otherwise.public ViewDeclarationLanguage getViewDeclarationLanguage(FacesContext context, String viewId)
Return the ViewDeclarationLanguage
instance
used for this ViewHandler
instance.
The default implementation must use
ViewDeclarationLanguageFactory.getViewDeclarationLanguage(java.lang.String)
to obtain
the appropriate ViewDeclarationLanguage
implementation for the argument
viewId
. Any exceptions thrown as a result of invoking that method must not be
swallowed.
The default implementation of this method returns null.
context
- the FacesContext
for this request.viewId
- the logical view id, as returned from
deriveLogicalViewId(javax.faces.context.FacesContext, java.lang.String)
for which the ViewDeclarationLanguage
should be returned.public Stream<String> getViews(FacesContext facesContext, String path, int maxDepth, ViewVisitOption... options)
Return a Stream
possibly lazily populated by walking the view trees of every active
ViewDeclarationLanguage
rooted at a given initial path. The view tree of every
ViewDeclarationLanguage
is individually traversed breadth-first as per the
contract of
ViewDeclarationLanguage.getViews(FacesContext, String, int, ViewVisitOption...)
. The
elements in the stream are logical view ids.
The maxDepth
parameter is the maximum depth of directory levels to visit for each
ViewDeclarationLanguage
beyond the initial path, which is always visited.
The value is relative to the root (/
), not to the given initial path. E.g. given
maxDepth
= 3
and initial path /foo/
, visiting will proceed up to
/foo/bar/
, where /
counts as depth 1
, /foo/
as depth
2
and /foo/bar/
as depth 3
. A value lower or equal to the depth of
the initial path means that only the initial path is visited. A value of
MAX_VALUE
may be used to indicate that all levels should be
visited.
In case more than one active ViewDeclarationLanguage
is present, the order in which
view ids from each ViewDeclarationLanguage
appear in the stream is undetermined,
except for the guarantee that every individual ViewDeclarationLanguage
is traversed
breadth-first.
facesContext
- The FacesContext
for this request.path
- The initial path from which to start looking for view ids.maxDepth
- The absolute maximum depth of nested directories to visit counted from the
root (/
).options
- The options to influence the traversal. See ViewVisitOption
for
details on those.Stream
of view idspublic Stream<String> getViews(FacesContext facesContext, String path, ViewVisitOption... options)
Return a Stream
possibly lazily populated by walking the view trees of every active
ViewDeclarationLanguage
rooted at a given initial path. The view tree of every
ViewDeclarationLanguage
is individually traversed breadth-first as per the
contract of
ViewDeclarationLanguage.getViews(FacesContext, String, int, ViewVisitOption...)
. The
elements in the stream are logical view ids.
This method works as if invoking it were equivalent to evaluating the expression:
Put differently, it visits all levels of the view tree.getViews(facesContext, start, Integer.MAX_VALUE, options)
In case more than one active ViewDeclarationLanguage
is present, the order in which
view ids from each ViewDeclarationLanguage
appear in the stream is undetermined,
except for the guarantee that every individual ViewDeclarationLanguage
is traversed
breadth-first.
facesContext
- The FacesContext
for this request.path
- The initial path from which to start looking for view ids.options
- The options to influence the traversal. See ViewVisitOption
for
details on those.Stream
of view idspublic abstract void writeState(FacesContext context) throws IOException
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
(PartialViewContext.processPartial(javax.faces.event.PhaseId)
)
.
context
- FacesContext
for the current requestIOException
- if an input/output error occursNullPointerException
- if context
is null
Comments to: faces-dev@eclipse.org.
Copyright © 2019 Eclipse Foundation. All rights reserved.
Use is subject to license terms.