My email-sending code (a Spring managed bean) is executed asychronous (using Springs #Async Annotation) because our email-server seems rather slow (takes 3-4 seconds until the mail is sent). The email method throws an checked excpetion if the email cannot be sent.
Now I'm sending emails from my JSF-managed bean (i.e. my controller), e.g. to send credentials to newly created users and want to show a growl Message to inform the (admin-)user that the email sending code threw an excpetion (I know that there will be a delay, but thats seems ok as it does not block the gui thread).
What I've done so far:
I implemented my custom AsyncUncaughtExceptionHandler, i.e. the method:
public class CustomAsyncExceptionHandler implements AsyncUncaughtExceptionHandler {
#Override
public void handleUncaughtException(Throwable throwable, Method method, Object... obj) {
// inform user that something went wrong (growl message)
}
}
This handler is then specified in Spring's XML config:
<bean id="exceptionHandler" class="org.myproject.util.CustomAsyncExceptionHandler" />
<task:annotation-driven executor="asyncExecutor" scheduler="asyncScheduler" exception-handler="exceptionHandler" />
<task:executor id="asyncExecutor" pool-size="5" />
<task:scheduler id="asyncScheduler" pool-size="10" /
The problem is that I cannot access the FacesContext in this exceptionHandler (which is a spring-managed bean).
How can I do this and if not, is there another way to let the user know that the async method threw an excpetion?
Related
How do I handle the exception and access the stack trace when an exception is thrown while processing a JSF ajax request? Right now, I only get the exception class name and message in a JavaScript alert when JSF project stage is set to Development. Even worse, there's no visual feedback whatsoever when JSF project stage is set to Production, and the server log doesn't show any information about the exception.
If that's relevant, I'm using GlassFish in Netbeans.
This problem is known and fleshed out in among others the OmniFaces FullAjaxExceptionHandler showcase.
By default, when an exception occurs during a JSF ajax request, the enduser would not get any form of feedback if the action was successfully performed or not. In Mojarra, only when the project stage is set to Development, the enduser would see a bare JavaScript alert with only the exception type and message.
The technical reason is that asynchronous requests (read: Ajax requests) by default don't return a synchronous response (read: a full page). Instead, they return small instructions and parts how to update the HTML DOM tree of the already-opened page. When an exception occurs, then these instructions are basically fully absent. Instead, some error information is sent back. You can usually handle them in the onerror attribute of the Ajax component and e.g. display an alert or perhaps perform a window.location change. At least, this is what JSF expected from you.
In order to catch and log the exception and optionally change the whole response, you basically need to create a custom ExceptionHandler. Standard JSF unfortunately doesn't provide a default one out the box (at least, not a sensible one). In your custom exception handler you will be able to get hands on the Exception instance causing all the trouble.
Here's a kickoff example:
public class YourExceptionHandler extends ExceptionHandlerWrapper {
private ExceptionHandler wrapped;
public YourExceptionHandler(ExceptionHandler wrapped) {
this.wrapped = wrapped;
}
#Override
public void handle() throws FacesException {
FacesContext facesContext = FacesContext.getCurrentInstance();
for (Iterator<ExceptionQueuedEvent> iter = getUnhandledExceptionQueuedEvents().iterator(); iter.hasNext();) {
Throwable exception = iter.next().getContext().getException(); // There it is!
// Now do your thing with it. This example implementation merely prints the stack trace.
exception.printStackTrace();
// You could redirect to an error page (bad practice).
// Or you could render a full error page (as OmniFaces does).
// Or you could show a FATAL faces message.
// Or you could trigger an oncomplete script.
// etc..
}
getWrapped().handle();
}
#Override
public ExceptionHandler getWrapped() {
return wrapped;
}
}
In order to get it to run, create a custom ExceptionHandlerFactory as follows:
public class YourExceptionHandlerFactory extends ExceptionHandlerFactory {
private ExceptionHandlerFactory parent;
public YourExceptionHandlerFactory(ExceptionHandlerFactory parent) {
this.parent = parent;
}
#Override
public ExceptionHandler getExceptionHandler() {
return new YourExceptionHandler(parent.getExceptionHandler());
}
}
Which needs to be registered in faces-config.xml as follows:
<factory>
<exception-handler-factory>com.example.YourExceptionHandlerFactory</exception-handler-factory>
</factory>
Alternatively, you can go ahead using the OmniFaces one. It will fully transparently make sure that exceptions during asynchronous requests behave the same as exceptions during synchronous requests, using <error-page> configuration in web.xml.
See also:
Why FullAjaxExceptionHandler does not simply perform an ExternalContext#redirect()?
Authorization redirect on session expiration does not work on submitting a JSF form, page stays the same
I wrote a Spring REST application. I tested it with curl command and it worked truly.
In another GWT Ajax application I have an RequestBuilder object that it does not work with my Spring Rest: after calling sendRequest method, the event onResponseReceived is fired but the getText method returns an empty string.
this is a part of my spring servlet.xml configuration file
<bean id="jsonmembertemplate"
class="org.springframework.web.servlet.view.json.MappingJacksonJsonView" >
<property name="contentType" value="text/javascript;charset=UTF-8"/>
<property name="disableCaching" value="false"/>
</bean>
<bean class="org.springframework.web.servlet.view.BeanNameViewResolver" />
and a part of my controller class
#RequestMapping(method = RequestMethod.GET, value="/member/get/{memberid}")
public String getMember(Model model, #PathVariable("memberid") int id, HttpServletResponse response) {
model.addAttribute("member", memberDao.get(id));
return "jsonmembertemplate";
}
and gwt code
private RequestBuilder rb = new RequestBuilder(RequestBuilder.GET, "http://localhost:8080/depna-nat-server/member/get/1?");
try {
rb.setHeader("Content-Type", "text/javascript;charset=UTF-8");
rb.sendRequest(null, new RequestCallback() {
#Override
public void onResponseReceived(Request request, Response response) {
Window.alert(Integer.toString(response.getStatusCode()));
Window.alert(response.getStatusText());
Window.alert(Integer.toString(response.getText().length()));
area.setText(response.getText());
}
#Override
public void onError(Request request, Throwable exception) {
Window.alert("fail");
}
});
} catch (RequestException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
I have a couple of gwt applications working with json and xml rest services offered by spring, we use spring instead of gwt (rpc or rf) because these services are offered to 3party apps as well.
I started my first project with RequestBuilder and we dind't have any problem, so maybe you have some issue in your code, could you inspect the traffic and post the errors you have?
If you are running a cross-domain issue (statusCode=0 normally means it) , add a filter to your servlet container, take a look to this document.
I finally opted to use gwtquery-ajax and gquery-data-binding because it made really easy to consume these services and to map them to java objects.
I have Spring MVC application where security is handled by Spring Security.
UI is built using GWT which gets the data from server using RPC approach.
I need to handle on UI the situation when session is expired:
For example RPC AsyncCallback can get SessionExpiredException type of exception and popup the window with message like "You session is expired, please click the refresh link" or something.
Did someone deal with such problem?
Thanks.
I suppose that for processing of incoming GWT call you use some Spring MVC controller or some servlet. It can have following logic
try{
// decode payload from GWT call
com.google.gwt.user.server.rpc.RPC.decodeRequest(...)
// get spring bean responsible for actual business logic
Object bean = applicationContext.getBean(beanName);
// execute business logic and encode response
return RPC.invokeAndEncodeResponse(bean, ….)
} catch (com.google.gwt.user.server.rpc.UnexpectedException ex) {
// send unexpected exception to client
return RPC.encodeResponseForFailure(..., new MyCustomUnexpectedException(), …) ;
}
Solution for this case
HttpServletRequest request = getRequest() ;
if (request.getRequestedSessionId() != null && !request.isRequestedSessionIdValid()) {
return RPC.encodeResponseForFailure(..., new MyCustomSessionExpiredException(), …) ;
} else {
// first code snippet goes here
}
Then catch custom session expired exception in a client side code. If you do not use RPC directly then provide more details about your bridge implementation between GWT and Spring.
You will need also force GWT compiler to include MyCustomSessionExpiredException type to a serialization white list (to prevent case when GWT security policy stops propogation of the exception to client side). Solution: include MyCustomSessionExpiredException type to each method signature of each synchronous interface:
#RemoteServiceRelativePath("productRpcService.rpc")
public interface ProductRpcService extends RemoteService {
List<Product> getAllProducts() throws ApplicationException;
void removeProduct(Product product) throws ApplicationException;
}
MyCustomSessionExpiredException extends ApplicationException
Then show pop-up in client side code:
public class ApplicationUncaughtExceptionHandler implements GWT.UncaughtExceptionHandler {
#Override
public void onUncaughtException(Throwable caught) {
if (caught instanceof MyCustomSessionExpiredException) {
Window.alert("Session expired");
}
}
}
// Inside of EntryPoint.onModuleLoad method
GWT.setUncaughtExceptionHandler(new ApplicationUncaughtExceptionHandler());
I researched a bit and uploaded the solution here http://code.google.com/p/gspring/source/browse/#svn%2Ftrunk%2Fsample%2Fsession-expired%253Fstate%253Dclosed.
Use mvn jetty:run-war to see the demo after checking it out and go to rpc-security-sample/index.htm
There are two ways to solve it.
The first is around to pass the delegate proxy for GWT RemoteServlet which throws SessionExpiredException during method invocation. This requires to declare Exception in every RPC service method. Example: http://code.google.com/p/gspring/source/browse/#svn%2Ftrunk%2Fsample%2Fsession-expired%253Fstate%253Dclosed
Steps:
Develop new filter which intercepts first
Declare SessionExpiredException in each RPC method service which could inherit RuntimeException for simplicity (no need to follow this in implementers)
Develop parent generic AsyncCallback handler
Use http://code.google.com/p/gspring/ solution to handle all incoming RCP requests.
The second which is much more simplest: return the 401 HTTP error and handle in UI side (GWT native general exception contains the HTTP status number). Example: http://code.google.com/p/gspring/source/browse/#svn%2Ftrunk%2Fsample%2Fsession-expired-401
The second approach is simplest and does not require declaring Exception in service methods contract. However following the first approach can give you some flexibility: it could contain some additional info like last login time (for SessionExpiredException) etc. Also the second approach can introduce new exceptions which are inherited from SecurityException like blacklisted user (for example if user was blacklisted during his session) or for example if user does the same actions very often like a robot (it could be asked for passing the captcha) etc.
I am making an ajax submit using Primefaces but I am having trouble linking my server side message with my ajax request.
Supposed I have this button that calls an action.
In my managed bean, do I need to raise an exception? How do I pass this message into my ajax request
public void checkout(ActionEvent event){
if(expression){
throw new CustomException("Account balance is not enough!");
}
}
public class CustomException extends RuntimeException {
public CustomException(String message) {
super(message);
}
}
How do I handle this case? Will my onerror javascript method be able to handle this?
Also, in one case supposed DB is down then how do I handle the exception? Do I have accessed to the error message
in my javascript function?
public void checkout(ActionEvent event){
try{
//DB is down
if(expression){
throw new CustomException("Account balance is not enough!");
}
}catch(Exception e){
}
}
As to your concrete question, you need to implement a custom ExceptionHandler for this which does basically the following when an exception occurs in an ajax request:
String errorPageLocation = "/WEB-INF/errorpages/500.xhtml";
context.setViewRoot(context.getApplication().getViewHandler().createView(context, errorPageLocation));
context.getPartialViewContext().setRenderAll(true);
context.renderResponse();
This is not exactly trivial if you want to take web.xml error pages into account. You'd need to parse the entire web.xml for this to find the error page locations. The OmniFaces utility library has exactly such an exception handler, the FullAjaxExceptionHandler. You can find the full source code here and the showcase example here.
As to your concrete functional requirement, I wouldn't throw an exception when there's just an user error. This is fully recoverable. You need to create and add a FacesMessage and have ajax to update the <h:messages>, <p:messages> or <p:growl>. The PrimeFaces ones support an autoUpdate="true" which would auto-update itself on ajax requests. E.g.
context.addMessage(null, new FacesMessage(FacesMessage.SEVERITY_ERROR, "Insufficient balance", null));
with
<p:messages autoUpdate="true" />
Throwing an exception makes only sense in unrecoverable situations like as when the DB is down. Note that you usually don't throw such an exception yourself. In case of JPA it would already be thrown as PersistenceException which you in turn shouldn't catch in JSF managed bean, but just let it go.
I want to handle exceptions so the URL information is automatically shown to the client. Is there an easy way to do this?
<bean id="outboundExceptionAdapter" class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerExceptionResolver">
<!-- what property to set here? -->
</bean>
You have two choices:
Spring Reference 15.9.1 HandlerExceptionResolver
Spring HandlerExceptionResolvers ease the pain of unexpected
exceptions that occur while your request is handled by a controller
that matched the request. HandlerExceptionResolvers somewhat resemble
the exception mappings you can define in the web application
descriptor web.xml. However, they provide a more flexible way to
handle exceptions. They provide information about which handler was
executing when the exception was thrown. Furthermore, a programmatic
way of handling exceptions gives you more options for responding
appropriately before the request is forwarded to another URL (the same
end result as when you use the servlet specific exception mappings).
The HandlerExceptionResolver has one method, containing everything you need:
HandlerExceptionResolver.resolveException(HttpServletRequest request,
HttpServletResponse response,
Object handler, Exception ex)
Or if you need different handlers for different controllers: Spring Reference Chapter 15.9.2 #ExceptionHandler
#ExceptionHandler(IOException.class)
public String handleIOException(IOException ex, HttpServletRequest request) {
return "every thing you asked for: " + request;
}
Short question short answer
I'm doing the following trick:
#ExceptionHandler(Exception.class)
public ModelAndView handleMyException(Exception exception) {
ModelAndView mv = new ModelAndView("redirect:errorMessage?error="+exception.getMessage());
return mv;
}
#RequestMapping(value="/errorMessage", method=RequestMethod.GET)
#Responsebody
public String handleMyExceptionOnRedirect(#RequestParamter("error") String error) {
return error;
}
Works flawless.