Following my previous question in Creating FacesMessage in action method outside JSF conversion/validation mechanism? , i'm trying to handle the exceptions thrown from the business layer outside my managed beans.
The strategy is to search and convert business exceptions to faces messages in the a PhaseListener,.
It is working as i expected, but im just wondering if im just reinventing the wheel, or doing it right with the wrong way ?
Here's my code sample snippet :
public class BusinessExceptionHandler implements PhaseListener {
#Override
public void afterPhase(PhaseEvent phaseEvent) {
ExceptionHandler exceptionHandler = phaseEvent.getFacesContext().getExceptionHandler();
// just debugging the handled exception, nothing here
/*
for (ExceptionQueuedEvent event : exceptionHandler.getHandledExceptionQueuedEvents()) {
ExceptionQueuedEventContext context = (ExceptionQueuedEventContext) event.getSource();
System.out.println("handled exception : " + context.getException());
}*/
for (Iterator<ExceptionQueuedEvent> it = exceptionHandler.getUnhandledExceptionQueuedEvents().iterator();
it.hasNext();) {
ExceptionQueuedEvent event = it.next();
ExceptionQueuedEventContext eventContext = (ExceptionQueuedEventContext) event.getSource();
Throwable e = eventContext.getException();
System.out.println("unhandled exception : " + e);
// get the root cause exception
while (e.getCause() != null) {
e = e.getCause();
}
System.out.println("cause exception : " + e +
", cause exception is BE : " + (e instanceof BusinessException));
// handle BE
if (e instanceof BusinessException) {
BusinessException be = (BusinessException) e;
System.out.println("processing BE " + be);
FacesMessage message = Messages.getMessage(
"com.corejsf.errors",
be.getMessage(),
be.getParamValues()
);
FacesContext context = FacesContext.getCurrentInstance();
context.addMessage(null, message);
it.remove(); // remove the exception
// works fine without this block, if BE is thrown, always return to the original page
/*
NavigationHandler navigationHandler = context.getApplication().getNavigationHandler();
System.out.println("navigating to " + context.getViewRoot().getViewId());
navigationHandler.handleNavigation(context, context.getViewRoot().getViewId(), null);
*/
}
}
}
#Override
public void beforePhase(PhaseEvent phaseEvent) {
}
#Override
public PhaseId getPhaseId() {
return PhaseId.INVOKE_APPLICATION;
}
}
Thank you !
Regards,
Albert Kam
Not sure why you're going this route, creating and registering your own exception handler is really easy. Though easier will be Seam Catch ( http://seamframework.org/Seam3/CatchModule and http://docs.jboss.org/seam/3/catch/3.0.0.Alpha1/reference/en-US/html_single/ ). I don't have a JSF bridge just yet, but it will be very easy to do. Then all you have to do is write one method that will handle a specific exception, and you'll be done!
Your approach is an intermix of JSF 1.x and JSF 2.x exception handling approaches. Since you're using JSF 2.x, I'd suggest a pure JSF 2.x approach without a PhaseListener and with help of the new ExceptionHandler API.
You can find an example which treats the ViewExpiredException in page 282 of the book "JSF 2.0: The Complete Reference" which is online available here (click the 1st result link).
Related
I maintain a web application that have a page with the JSF tag <f:event. I have rewrote a method in a service class for it to throw a business exception. However, when the business exception is thrown, it isn't caught in managed bean and the exception is showed on the page. Seems that my code try/catch doesn't work.
In XHTML:
<f:event listener="#{resourceBean.init(enrollment)}" type="preRenderView" />
Listener method in Managed Bean:
private boolean canCreateResource;
public void init(Enrollment enrollment) {
(...)
try {
canCreateResource = resourceService.canCreateResource(enrollment);
} catch (BusinessException e) {
canCreateResource = false;
}
}
Method in service class:
public boolean canCreateResource(Enrollment enrollment) {
if (...) {
if (mandateService.isCoordinator(user, course)) {
return true;
} else {
throw new BusinessException("Undefined business rule.");
}
}
return false;
}
From what I read on other sites, I suppose I have to implement some JSF's handler class. But which and how?
EDITED
OBS 1: The BusinessException class extends RuntimeException class.
OBS 2: The attribute canCreateResource was created to control the render of a button.
It's because you threw a RuntimeException from an EJB.
When such RuntimeException is not annotated with #ApplicationException, then the EJB container will wrap it in an javax.ejb.EJBException and rethrow it. This is done so because runtime exceptions are usually only used to indicate bugs in code logic, i.e. programmer's mistakes and not enduser's mistakes. You know, NullPointerException, IllegalArgumentException, IndexOutOfBoundsException, NumberFormatException and friends. This allows the EJB client to have one catch-all point for such runtime exceptions, like catch (EJBException e) { There's a bug in the service layer or in the way how we are using it! }
If you had tried catch (Exception e) and inspected the actual exception, then you'd have noticed that.
Fix your BusinessException class accordingly to add that annotation, it will then be recognized as a real application exception and not be wrapped in an EJBException:
#ApplicationException(rollback=true)
public class BusinessException extends RuntimeException {
// ...
}
Do note that in case you throw an non-RuntimeException, then you still need to keep the annotation on that, explicitly with rollback=true, because by default it wouldn't perform a rollback, on the contrary to a RuntimeException without the annotation.
#ApplicationException(rollback=true)
public class BusinessException extends Exception {
// ...
}
Summarized:
RuntimeException thrown from transactional EJB method will perform full rollback, but exception will be wrapped in EJBException.
RuntimeException with #ApplicationException from transactional EJB method will only perform full rollback when rollback=true is explicitly set.
Exception from transactional EJB method will not perform full rollback.
Exception with #ApplicationException from transactional EJB method will only perform full rollback when rollback=true is explicitly set.
Note that #ApplicationException is inherited over all subclasses of the custom exception, so you don't need to repeat it over all of them. Best would be to have it as an abstract class. See also the examples in the related question linked below.
See also:
Letting the presentation layer (JSF) handle business exceptions from service layer (EJB)
If isCoordinator method can eventually throw an exception you should add a try catch block inside canCreateResource method. You can throw your own exception or propagate the original one. In both cases you have to declare it in the method signature. If you throw BusinessException:
public void canCreateResource(Enrollment enrollment) throws BusinessException
Do not return any value. Or return a boolean value but do not throw any exception.
In the catch block inside the init method add the Facelet message exception:
...
} catch (BusinessException e) {
this.canCreateResource = false;
FacesContext.getCurrentInstance().addMessage(null,
new FacesMessage(FacesMessage.SEVERITY_ERROR, e.getMessage(), ""));
}
}
Also in your page you have to add <h:messages> tag.
In case you want to catch an exception that you did not create yourself (and you are not able to annotate with #ApplicationException), you can catch all exceptions and see if one of the causes is of the type you want to catch.
You can check the causes of the exception recursively:
public static <T extends Throwable> T getCauseOfType(final Throwable throwable,
final Class<T> type) {
if (throwable == null) {
return null;
}
return type.isInstance(throwable) ? (T) throwable : getCauseOfType(throwable.getCause(), type);
}
public static <T extends Throwable> boolean hasCauseOfType(final Throwable throwable,
final Class<T> type) {
return getCauseOfType(throwable, type) != null;
}
You can use this like:
try {
...
}
catch (Exception e) {
if (hasCauseOfType(e, SomeException.class)) {
// Special handling
}
else {
throw e;
}
}
I've a problem with a bean that doesn't dispatch the response to another page.
This is the code:
#ManagedBean(name = "ssoServiceBean")
public class SSOServiceBean {
#ManagedProperty(value="#{param.samlRequest}")
private String samlRequest;
#ManagedProperty(value="#{param.relayState}")
private String relayState;
#PostConstruct
public void submit() {
System.out.println("1) PostConstruct method called");
//samlRequest = FacesContext.getCurrentInstance().getExternalContext().getRequestParameterMap().get("samlRequest");
//relayState = FacesContext.getCurrentInstance().getExternalContext().getRequestParameterMap().get("relayState");
processResponse();
}
//getters and setters omitted for succinctness
private void processResponse(){
System.out.println("2) Processing response");
String uri;
if(samlRequest != null && !samlRequest.equals("") && relayState != null && !relayState.equals("")) {
System.out.println("SAMLRequest: "+samlRequest);
System.out.println("RelayState: "+relayState);
uri = "challenge.xhtml";
System.out.println("3) Sending challenge...");
} else {
uri = "dashboard.xhtml";
System.out.println("3) Sending dashboard...");
}
try {
FacesContext.getCurrentInstance().getExternalContext().dispatch(uri);
System.out.println("4) Done.");
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
The problem is that the dispatch() method doesn't work properly, and seems to be ignored.
Infact the system responses with an error of the related bean's page ssoservice.xhtml
I've used the Postconstruct annotation because with this bean I've to intercept POST parameters that come from a third-party page.
Once I've received the post parameters, I've to render the challenge.xhtml page, WITHOUT using a redirect directive.
Nextly, the user will submit challenge.xhtml to the related bean ChallengeBean.java .
So, what is the problem? Why dispatch doesn't work?
The EJB method (using CMT) that updates an entity supplied :
#Override
#SuppressWarnings("unchecked")
public boolean update(Entity entity) throws OptimisticLockException {
// Code to merge the entity.
return true;
}
This will throw the javax.persistence.OptimisticLockException, if concurrent update is detected which is to be handled precisely by the caller (a managed bean).
public void onRowEdit(RowEditEvent event) {
try {
service.update((Entity) event.getObject())
} catch(OptimisticLockException e) {
// Add a user-friendly faces message.
}
}
But doing so makes an additional dependency from the javax.persistence API on the presentation layer compulsory which is a design smell leading to tight-coupling.
In which exception should it be wrapped so that the tight-coupling issue can be omitted in its entirely? Or is there a standard way to handle this exception which in turn does not cause any service layer dependencies to be enforced on the presentation layer?
By the way, I found it clumsy to catch this exception in the EJB (on the service layer itself) and then return a flag value to the client (JSF).
Create a custom service layer specific runtime exception which is annotated with #ApplicationException with rollback=true.
#ApplicationException(rollback=true)
public abstract class ServiceException extends RuntimeException {}
Create some concrete subclasses for general business exceptions, such as constraint violation, required entity, and of course optimistic lock.
public class DuplicateEntityException extends ServiceException {}
public class EntityNotFoundException extends ServiceException {}
public class EntityAlreadyModifiedException extends ServiceException {}
Some of them can be thrown directly.
public void register(User user) {
if (findByEmail(user.getEmail()) != null) {
throw new DuplicateEntityException();
}
// ...
}
public void addToOrder(OrderItem item, Long orderId) {
Order order = orderService.getById(orderId);
if (order == null) {
throw new EntityNotFoundException();
}
// ...
}
Some of them need a global interceptor.
#Interceptor
public class ExceptionInterceptor implements Serializable {
#AroundInvoke
public Object handle(InvocationContext context) throws Exception {
try {
return context.proceed();
}
catch (javax.persistence.EntityNotFoundException e) { // Can be thrown by Query#getSingleResult().
throw new EntityNotFoundException(e);
}
catch (OptimisticLockException e) {
throw new EntityAlreadyModifiedException(e);
}
}
}
Which is registered as default interceptor (on all EJBs) as below in ejb-jar.xml.
<interceptors>
<interceptor>
<interceptor-class>com.example.service.ExceptionInterceptor</interceptor-class>
</interceptor>
</interceptors>
<assembly-descriptor>
<interceptor-binding>
<ejb-name>*</ejb-name>
<interceptor-class>com.example.service.ExceptionInterceptor</interceptor-class>
</interceptor-binding>
</assembly-descriptor>
As a general hint, in JSF you can also have a global exception handler which just adds a faces message. When starting with this kickoff example, you could do something like this in YourExceptionHandler#handle() method:
if (exception instanceof EntityAlreadyModifiedException) { // Unwrap if necessary.
// Add FATAL faces message and return.
}
else {
// Continue as usual.
}
I'm trying to invoke a method from javascript object which in turn calls a the following java method :
public void loadPicture(final String absolutePath) {
System.out.println("loadPicture " + absolutePath);
Image dbimage;
dbimage = new Image(absolutePath, 100.0d, 100.0d, false, false);
final ImageView dbImageView = new ImageView();
dbImageView.setImage(dbimage);
Platform.runLater(new Runnable() {
#Override
public void run() {
try {
System.out.println("hbox children : "+hbox.getChildren().size());
hbox.getChildren().add(dbImageView);
System.out.println("hbox children : "+hbox.getChildren().size());
//test
//logger.debug(" aggiunto "+absolutePath);
DropPictures.getPicturesNames().add(absolutePath);
} catch (Exception e) {
System.out.println("eccezione :" + e.getLocalizedMessage());
}
}
});
}
In javascript the method invocation is :
var a = document.getElementById(myDivId);
a.loadPicture();
I've traced the execution and the above method doesn't throw any exception,but it is run cause i see the output in java console, but the applet doesn't show the picture.
I've used Platform.runLater to update the GUI in the javafx thread, still no update is performed.
Is anyone aware of a method to dynamically combine/minify all the h:outputStylesheet resources and then combine/minify all h:outputScript resources in the render phase? The comined/minified resource would probably need to be cached with a key based on the combined resource String or something to avoid excessive processing.
If this feature doesn't exist I'd like to work on it. Does anyone have ideas on the best way to implement something like this. A Servlet filter would work I suppose but the filter would have to do more work than necessary -- basically examining the whole rendered output and replacing matches. Implementing something in the render phase seems like it would work better as all of the static resources are available without having to parse the entire output.
Thanks for any suggestions!
Edit: To show that I'm not lazy and will really work on this with some guidance, here is a stub that captures Script Resources name/library and then removes them from the view. As you can see I have some questions about what to do next ... should I make http requests and get the resources to combine, then combine them and save them to the resource cache?
package com.davemaple.jsf.listener;
import java.util.ArrayList;
import java.util.List;
import javax.faces.component.UIComponent;
import javax.faces.component.UIOutput;
import javax.faces.component.UIViewRoot;
import javax.faces.context.FacesContext;
import javax.faces.event.AbortProcessingException;
import javax.faces.event.PhaseEvent;
import javax.faces.event.PhaseId;
import javax.faces.event.PhaseListener;
import javax.faces.event.PreRenderViewEvent;
import javax.faces.event.SystemEvent;
import javax.faces.event.SystemEventListener;
import org.apache.log4j.Logger;
/**
* A Listener that combines CSS/Javascript Resources
*
* #author David Maple<d#davemaple.com>
*
*/
public class ResourceComboListener implements PhaseListener, SystemEventListener {
private static final long serialVersionUID = -8430945481069344353L;
private static final Logger LOGGER = Logger.getLogger(ResourceComboListener.class);
#Override
public PhaseId getPhaseId() {
return PhaseId.RESTORE_VIEW;
}
/*
* (non-Javadoc)
* #see javax.faces.event.PhaseListener#beforePhase(javax.faces.event.PhaseEvent)
*/
public void afterPhase(PhaseEvent event) {
FacesContext.getCurrentInstance().getViewRoot().subscribeToViewEvent(PreRenderViewEvent.class, this);
}
/*
* (non-Javadoc)
* #see javax.faces.event.PhaseListener#afterPhase(javax.faces.event.PhaseEvent)
*/
public void beforePhase(PhaseEvent event) {
//nothing here
}
/*
* (non-Javadoc)
* #see javax.faces.event.SystemEventListener#isListenerForSource(java.lang.Object)
*/
public boolean isListenerForSource(Object source) {
return (source instanceof UIViewRoot);
}
/*
* (non-Javadoc)
* #see javax.faces.event.SystemEventListener#processEvent(javax.faces.event.SystemEvent)
*/
public void processEvent(SystemEvent event) throws AbortProcessingException {
FacesContext context = FacesContext.getCurrentInstance();
UIViewRoot viewRoot = context.getViewRoot();
List<UIComponent> scriptsToRemove = new ArrayList<UIComponent>();
if (!context.isPostback()) {
for (UIComponent component : viewRoot.getComponentResources(context, "head")) {
if (component.getClass().equals(UIOutput.class)) {
UIOutput uiOutput = (UIOutput) component;
if (uiOutput.getRendererType().equals("javax.faces.resource.Script")) {
String library = uiOutput.getAttributes().get("library").toString();
String name = uiOutput.getAttributes().get("name").toString();
// make https requests to get the resources?
// combine then and save to resource cache?
// insert new UIOutput script?
scriptsToRemove.add(component);
}
}
}
for (UIComponent component : scriptsToRemove) {
viewRoot.getComponentResources(context, "head").remove(component);
}
}
}
}
This answer doesn't cover minifying and compression. Minifying of individual CSS/JS resources is better to be delegated to build scripts like YUI Compressor Ant task. Manually doing it on every request is too expensive. Compression (I assume you mean GZIP?) is better to be delegated to the servlet container you're using. Manually doing it is overcomplicated. On Tomcat for example it's a matter of adding a compression="on" attribute to the <Connector> element in /conf/server.xml.
The SystemEventListener is already a good first step (apart from some PhaseListener unnecessity). Next, you'd need to implement a custom ResourceHandler and Resource. That part is not exactly trivial. You'd need to reinvent pretty a lot if you want to be JSF implementation independent.
First, in your SystemEventListener, you'd like to create new UIOutput component representing the combined resource so that you can add it using UIViewRoot#addComponentResource(). You need to set its library attribute to something unique which is understood by your custom resource handler. You need to store the combined resources in an application wide variable along an unique name based on the combination of the resources (a MD5 hash maybe?) and then set this key as name attribute of the component. Storing as an application wide variable has a caching advantage for both the server and the client.
Something like this:
String combinedResourceName = CombinedResourceInfo.createAndPutInCacheIfAbsent(resourceNames);
UIOutput component = new UIOutput();
component.setRendererType(rendererType);
component.getAttributes().put(ATTRIBUTE_RESOURCE_LIBRARY, CombinedResourceHandler.RESOURCE_LIBRARY);
component.getAttributes().put(ATTRIBUTE_RESOURCE_NAME, combinedResourceName + extension);
context.getViewRoot().addComponentResource(context, component, TARGET_HEAD);
Then, in your custom ResourceHandler implementation, you'd need to implement the createResource() method accordingly to create a custom Resource implementation whenever the library matches the desired value:
#Override
public Resource createResource(String resourceName, String libraryName) {
if (RESOURCE_LIBRARY.equals(libraryName)) {
return new CombinedResource(resourceName);
} else {
return super.createResource(resourceName, libraryName);
}
}
The constructor of the custom Resource implementation should grab the combined resource info based on the name:
public CombinedResource(String name) {
setResourceName(name);
setLibraryName(CombinedResourceHandler.RESOURCE_LIBRARY);
setContentType(FacesContext.getCurrentInstance().getExternalContext().getMimeType(name));
this.info = CombinedResourceInfo.getFromCache(name.split("\\.", 2)[0]);
}
This custom Resource implementation must provide a proper getRequestPath() method returning an URI which will then be included in the rendered <script> or <link> element:
#Override
public String getRequestPath() {
FacesContext context = FacesContext.getCurrentInstance();
String path = ResourceHandler.RESOURCE_IDENTIFIER + "/" + getResourceName();
String mapping = getFacesMapping();
path = isPrefixMapping(mapping) ? (mapping + path) : (path + mapping);
return context.getExternalContext().getRequestContextPath()
+ path + "?ln=" + CombinedResourceHandler.RESOURCE_LIBRARY;
}
Now, the HTML rendering part should be fine. It'll look something like this:
<link type="text/css" rel="stylesheet" href="/playground/javax.faces.resource/dd08b105bf94e3a2b6dbbdd3ac7fc3f5.css.xhtml?ln=combined.resource" />
<script type="text/javascript" src="/playground/javax.faces.resource/2886165007ccd8fb65771b75d865f720.js.xhtml?ln=combined.resource"></script>
Next, you have to intercept on combined resource requests made by the browser. That's the hardest part. First, in your custom ResourceHandler implementation, you need to implement the handleResourceRequest() method accordingly:
#Override
public void handleResourceRequest(FacesContext context) throws IOException {
if (RESOURCE_LIBRARY.equals(context.getExternalContext().getRequestParameterMap().get("ln"))) {
streamResource(context, new CombinedResource(getCombinedResourceName(context)));
} else {
super.handleResourceRequest(context);
}
}
Then you have to do the whole lot of work of implementing the other methods of the custom Resource implementation accordingly such as getResponseHeaders() which should return proper caching headers, getInputStream() which should return the InputStreams of the combined resources in a single InputStream and userAgentNeedsUpdate() which should respond properly on caching related requests.
#Override
public Map<String, String> getResponseHeaders() {
Map<String, String> responseHeaders = new HashMap<String, String>(3);
SimpleDateFormat sdf = new SimpleDateFormat(PATTERN_RFC1123_DATE, Locale.US);
sdf.setTimeZone(TIMEZONE_GMT);
responseHeaders.put(HEADER_LAST_MODIFIED, sdf.format(new Date(info.getLastModified())));
responseHeaders.put(HEADER_EXPIRES, sdf.format(new Date(System.currentTimeMillis() + info.getMaxAge())));
responseHeaders.put(HEADER_ETAG, String.format(FORMAT_ETAG, info.getContentLength(), info.getLastModified()));
return responseHeaders;
}
#Override
public InputStream getInputStream() throws IOException {
return new CombinedResourceInputStream(info.getResources());
}
#Override
public boolean userAgentNeedsUpdate(FacesContext context) {
String ifModifiedSince = context.getExternalContext().getRequestHeaderMap().get(HEADER_IF_MODIFIED_SINCE);
if (ifModifiedSince != null) {
SimpleDateFormat sdf = new SimpleDateFormat(PATTERN_RFC1123_DATE, Locale.US);
try {
info.reload();
return info.getLastModified() > sdf.parse(ifModifiedSince).getTime();
} catch (ParseException ignore) {
return true;
}
}
return true;
}
I've here a complete working proof of concept, but it's too much of code to post as a SO answer. The above was just a partial to help you in the right direction. I assume that the missing method/variable/constant declarations are self-explaining enough to write your own, otherwise let me know.
Update: as per the comments, here's how you can collect resources in CombinedResourceInfo:
private synchronized void loadResources(boolean forceReload) {
if (!forceReload && resources != null) {
return;
}
FacesContext context = FacesContext.getCurrentInstance();
ResourceHandler handler = context.getApplication().getResourceHandler();
resources = new LinkedHashSet<Resource>();
contentLength = 0;
lastModified = 0;
for (Entry<String, Set<String>> entry : resourceNames.entrySet()) {
String libraryName = entry.getKey();
for (String resourceName : entry.getValue()) {
Resource resource = handler.createResource(resourceName, libraryName);
resources.add(resource);
try {
URLConnection connection = resource.getURL().openConnection();
contentLength += connection.getContentLength();
long lastModified = connection.getLastModified();
if (lastModified > this.lastModified) {
this.lastModified = lastModified;
}
} catch (IOException ignore) {
// Can't and shouldn't handle it here anyway.
}
}
}
}
(the above method is called by reload() method and by getters depending on one of the properties which are to be set)
And here's how the CombinedResourceInputStream look like:
final class CombinedResourceInputStream extends InputStream {
private List<InputStream> streams;
private Iterator<InputStream> streamIterator;
private InputStream currentStream;
public CombinedResourceInputStream(Set<Resource> resources) throws IOException {
streams = new ArrayList<InputStream>();
for (Resource resource : resources) {
streams.add(resource.getInputStream());
}
streamIterator = streams.iterator();
streamIterator.hasNext(); // We assume it to be always true; CombinedResourceInfo won't be created anyway if it's empty.
currentStream = streamIterator.next();
}
#Override
public int read() throws IOException {
int read = -1;
while ((read = currentStream.read()) == -1) {
if (streamIterator.hasNext()) {
currentStream = streamIterator.next();
} else {
break;
}
}
return read;
}
#Override
public void close() throws IOException {
IOException caught = null;
for (InputStream stream : streams) {
try {
stream.close();
} catch (IOException e) {
if (caught == null) {
caught = e; // Don't throw it yet. We have to continue closing all other streams.
}
}
}
if (caught != null) {
throw caught;
}
}
}
Update 2: a concrete and reuseable solution is available in OmniFaces. See also CombinedResourceHandler showcase page and API documentation for more detail.
You may want to evaluate JAWR before implementing your own solution. I've used it in couple of projects and it was a big success. It used in JSF 1.2 projects but I think it will be easy to extend it to work with JSF 2.0. Just give it a try.
Omnifaces provided CombinedResourceHandler is an excellent utility, but I also love to share about this excellent maven plugin:- resources-optimizer-maven-plugin that can be used to minify/compress js/css files &/or aggregate them into fewer resources during the build time & not dynamically during runtime which makes it a more performant solution, I believe.
Also have a look at this excellent library as well:- webutilities
I have an other solution for JSF 2. Might also rok with JSF 1, but i do not know JSF 1 so i can not say. The Idea works mainly with components from h:head and works also for stylesheets. The result
is always one JavaScript (or Stylesheet) file for a page! It is hard for me to describe but i try.
I overload the standard JSF ScriptRenderer (or StylesheetRenderer) and configure the renderer
for the h:outputScript component in the faces-config.xml.
The new Renderer will now not write anymore the script-Tag but it will collect all resources
in a list. So first resource to be rendered will be first item in the list, the next follows
and so on. After last h:outputScript component ist rendered, you have to render 1 script-Tag
for the JavaScript file on this page. I make this by overloading the h:head renderer.
Now comes the idea:
I register an filter! The filter will look for this 1 script-Tag request. When this request comes,
i will get the list of resources for this page. Now i can fill the response from the list of
resources. The order will be correct, because the JSF rendering put the resources in correct order
into the list. After response is filled, the list should be cleared. Also you can do more
optimizations because you have the code in the filter....
I have code that works superb. My code also can handle browser caching and dynamic script rendering.
If anybody is interested i can share the code.