public class JspViewHandlerImpl extends ViewHandler
This implementation works tightly together with the various JSP TagHandler classes to implement the behaviour mandated by the ViewHandler specification.
Rendering of a view is done in two parts: first a jsp-generated servlet is invoked to create or refresh a jsf component tree, then the component tree is walked to generate the output to send to the user.
The invoked servlet is the one generated from the jsp file which corresponds to the viewId of the view being rendered. As is normal for jsp, this servlet alternates between writing literal text to the response output stream and invoking "tag handler" classes representing the jsp tags that were present in the page. This servlet is not aware of JSF at all.
On the first visit to a view, when each JSF taghandler is invoked, the corresponding JSF component will not yet exist so it is created and added to the current view tree. Each JSF taghandler also marks itself as having "buffered body content", which means that after the start-tag is executed a temporary output stream is installed for the response. Any output generated by the jsp-servlet therefore gets written into a memory buffer rather than sent via the network socket to the sender of the request. When the end of the JSF tag is encountered, the JSF tag checks whether any such body text did exist, and if so it creates a transient f:verbatim component and inserts it into the component tree. The final result is that after this "first pass" a component tree exists which has all the JSF components in it, plus a bunch of auto-generated f:verbatim components that hold all plain text, or output generated by non-jsf jsp tags. Absolutely NO output has yet been sent to the real response stream.
On later visits to the same view, the component tree already exists (has been restored). However the "verbatim" components holding static text are not present as they were marked "transient" (not keeping them reduces the amount of memory required to "save state"). Note that these components are not needed for any phase prior to RENDER because they are not "input" components. When the jsp-generated servlet is executed, JSF taghandlers that are invoked will simply verify that a corresponding component already exists in the view-tree rather than creating a new one. However the "body buffering" occurs again, so that the appropriate transient verbatim components are once again created and inserted into the tree.
Regardless of whether the view is new or restored, the rendered output can now be generated simply by walking the component tree and invoking the encodeBegin/encodeChildren/encodeEnd methods on each component. The static components simply output their contained text.
Notes for JSF1.1 users: the new two-phase approach that uses "output buffering" to capture non-JSF output is rather like wrapping all non-jsf components in an invisible f:verbatim tag. Although that doesn't sound like a big change, it allows processing to occur in two passes rather than one. And that means that before any component is rendered the entire component tree already exists. This solves a number of JSF1.1 problems, including output-ordering problems between text and jsf components, and errors when using the "for" attribute of a label to reference a component later in the page. It does introduce a performance penalty; non-JSF-generated output now gets buffered rather than being streamed directly to the user.
| Modifier and Type | Field and Description |
|---|---|
static String |
FORM_STATE_MARKER |
static int |
FORM_STATE_MARKER_LEN |
CHARACTER_ENCODING_KEY, DEFAULT_FACELETS_SUFFIX, DEFAULT_SUFFIX, DEFAULT_SUFFIX_PARAM_NAME, FACELETS_SUFFIX_PARAM_NAME, FACELETS_VIEW_MAPPINGS_PARAM_NAME| Constructor and Description |
|---|
JspViewHandlerImpl() |
| Modifier and Type | Method and Description |
|---|---|
Locale |
calculateLocale(FacesContext facesContext)
Get the locales specified as acceptable by the original request, compare them to the
locales supported by this Application and return the best match.
|
String |
calculateRenderKitId(FacesContext facesContext) |
UIViewRoot |
createView(FacesContext facesContext,
String viewId)
Create a UIViewRoot object and return it; the returned object has no children.
|
String |
getActionURL(FacesContext facesContext,
String viewId)
Return a string containing a webapp-relative URL that the user can invoke
to render the specified view.
|
String |
getResourceURL(FacesContext facesContext,
String path) |
protected ViewHandlerSupport |
getViewHandlerSupport() |
void |
renderView(FacesContext facesContext,
UIViewRoot viewToRender)
Generate output to the user by combining the data in the jsp-page specified by viewToRender
with the existing JSF component tree (if any).
|
UIViewRoot |
restoreView(FacesContext facesContext,
String viewId)
Just invoke StateManager.restoreView.
|
void |
setViewHandlerSupport(ViewHandlerSupport viewHandlerSupport) |
void |
writeState(FacesContext facesContext)
Writes a state marker that is replaced later by one or more hidden form
inputs.
|
calculateCharacterEncoding, deriveViewId, getBookmarkableURL, getRedirectURL, getViewDeclarationLanguage, initViewpublic static final String FORM_STATE_MARKER
public static final int FORM_STATE_MARKER_LEN
public void setViewHandlerSupport(ViewHandlerSupport viewHandlerSupport)
viewHandlerSupport - the viewHandlerSupport to setprotected ViewHandlerSupport getViewHandlerSupport()
public Locale calculateLocale(FacesContext facesContext)
calculateLocale in class ViewHandlerpublic String calculateRenderKitId(FacesContext facesContext)
calculateRenderKitId in class ViewHandlerpublic UIViewRoot createView(FacesContext facesContext, String viewId)
As required by the spec, the returned object inherits locale and renderkit settings from the viewRoot currently configured for the facesContext (if any). This means that on navigation from one view to another these settings are "inherited".
createView in class ViewHandlerpublic String getActionURL(FacesContext facesContext, String viewId)
URLs and ViewIds are not quite the same; for example a url of "/foo.jsf" or "/faces/foo.jsp" may be needed to access the view "/foo.jsp".
This method simply delegates to ViewHandlerSupport.calculateActionURL.
getActionURL in class ViewHandlerpublic String getResourceURL(FacesContext facesContext, String path)
getResourceURL in class ViewHandlerpublic void renderView(FacesContext facesContext, UIViewRoot viewToRender) throws IOException, FacesException
As described in the class documentation, this first runs the jsp-generated servlet to create or enhance the JSF component tree - including verbatim nodes for any non-jsf data in that page.
The component tree is then walked to generate the appropriate output for each component.
renderView in class ViewHandlerIOExceptionFacesExceptionpublic UIViewRoot restoreView(FacesContext facesContext, String viewId)
restoreView in class ViewHandlerpublic void writeState(FacesContext facesContext) throws IOException
The problem with html is that the only place to encode client-side state is in a hidden html input field. However when a form is submitted, only the fields within a particular form are sent; fields in other forms are not sent. Therefore the view tree state must be written into every form in the page. This method is therefore invoked at the end of every form.
Theoretically the state of a component tree will not change after rendering starts. Therefore it is possible to create a serialized representation of that state at the start of the rendering phase (or when first needed) and output it whenever needed as described above. However this is not currently implemented; instead the entire page being generated is buffered, and a "marker" string is output instead of the tree state. After the rendering pass is complete the component final tree state is computed and the buffer is then post-processed to replace the "marker" strings with the real data.
This method also supports "javascript viewstate". TODO: document this.
writeState in class ViewHandlerfacesContext - IOExceptionCopyright © 2016 The Apache Software Foundation. All Rights Reserved.