From a jsp is thrown a NullPointerException for example using <% null.toString(); %>
This exception is not handled by the HandlerExceptionResolver, but thrown to the web container(tomcat) and converted into a code 500 error.
How can I configure spring to get that error in my HandlerExceptionResolver ?
Details:
Spring can be configured to handle exceptions thrown inside Controllers, but not exceptions thrown by view.
Of course i can resolve the NullPointerException, but i want to design a solution that will gracefully resolve any possible problem on the web application in order to display a user friendly message to the user.
See the HandlerInterceptor interface instead. You'll want the afterCompletion method. You can then intercept the response and then set the appropriate header information to redirect to a container-configured error web page. You're right that Spring doesn't have this functionality, this is going to have to be specified by the web.xml which determines which codes map to which pages.
I have not worked with this particular bit of the spring framework, but the docs say
"Interface to be implemented by objects than can resolve exceptions thrown during handler mapping or execution, in the typical case to error views. Implementors are typically registered as beans in the application context.
Error views are analogous to the error page JSPs, but can be used with any kind of exception including any checked exception, with potentially fine-granular mappings for specific handlers."
so I'd imagine that given that NullPointer extends RuntimeException the framework isn't designed to catch it. Is there a reason the exception(s) can't be handled in the controller directly?
Related
Having added the error.html Thymeleaf template to replace the default error page on Spring how can I get access to the exception on that page?
So I have custom exception thrown on some controller. How to access that exception on the Thymeleaf page?
I want this to work globally, so any controller thrown exception should be accessible.
Case 1: For customized error pages with spring default error info
There are some predefined objects in Thymeleaf to show error information, e.g. ${error}, ${exception} and so on. These objects can be used in your customized error page.
This article will help you more. Custom Error Page with Thymeleaf
Case 2: For customized error pages with customized error info
There are #ControllerAdvice and #ExceptionHandler used to handle exceptions in controllers globally. A certain exception can be add to Modal's attribute and therefore accessed in thymeleaf templates. However, please be noted that the solution does not work in Webflux.
The blog shows details about the solution. Exception Handling in Spring MVC
I am creating a Spring Boot web application, but i am confused why people use Global Exception handlers(#ControllerAdvice) when there is Error Page Registrar which is neater and more explicit. Please can someone explain more and is it possible to call an Error page registrar from a global Exception Handler Class( class annoted with #ControllerAdvice, with an #Exceptionhandler method).
As Brian answer, I think you can do this. I got a sample to prove this one in here if you still need to refer: https://github.com/kennytai/SampleSpringbootExceptionHandler
At this sample, I use the #ControllerAdvice in class GlobalExceptionHandler to manage all exceptions from TestController.
Hope this help.
It's actually the opposite the error pages mechanism in Spring Boot is the global one; it's catching all exceptions unhandled by the application. Note that in a Servlet environment, it's even dispatching the request back into the container on the /error path.
You're right though, this mechanism is really powerful and you can achieve a lot with it.
The other exception handling mechanisms you're mentioning are provided by Spring MVC itself. They're executed during the handling of the request and don't require an additional dispatch to the container. In some cases, they can be more limited because they offer less features than the full ErrorController (which is an MVC Controller).
But unlike error pages, you can configure those to focus on only specific errors:
You can declare an #ExceptionHandler within a Controller and specify the type of Exception you'd like to handle
You can configure the #ControllerAdvice annotation to only apply to specific packages, Controllers extending a specific interface or annotated with a specific annotation
I'd say the latter are quite useful when you want to deal with business exceptions at the controller level. You can do that with error pages, but you might end up with a single error controller dealing with too many things.
I have done some research around this with conflicting results. To handle this error, some say that I need to implement HandlerExceptionResolver in one of my controllers.
Here are some links for that:
How to handle MaxUploadSizeExceededException
Handling MaxUploadSizeExceededException with Spring MVC
http://www.raistudies.com/spring/spring-mvc/file-upload-spring-mvc-annotation/
On the other hand, other people are saying that this approach is futile such that the Exception is occuring outside the request handling flow:
http://forum.spring.io/forum/spring-projects/web/124409-handling-maxuploadsizeexceededexception-in-spring (The second poster in the thread)
MaxUploadSizeExceededException doesn't invoke the exception handling method in Spring
I have tried the above solutions but they do not work for me. It appears that the Exception occurs outside of Spring, as expected. I am unable to catch this even with HandlerExceptionResolver.
Trying following the approach specified in the link below. Basically, you configure an error page for any un handled exception and then define a handler for the error page. Looks like a decent workaround.
Here is the link http://www.javacodegeeks.com/2013/11/how-to-custom-error-pages-in-tomcat-with-spring-mvc.html
Hope this helps.
I am using Spring Hibernate integration in my application and DAO classes are extending HibernateDaoSupport.
Suppose I save some object using the code
getHibernateTemplate().save(object);
As Spring Hibernate integration doesn't mandate to write try-catch block, but suppose if any exception is thwron while saving that object.
Then what is the best way to handle it? I means should I catch it in the service layer and wrap it in some user defined excpetions.
Do I need to write try-catch in DAO layer method itself in case I want to log which method in DAO throws exception?
I have never used HibernateDaoSupport or Hibernate Template before so ignorant about exception handling. Please provide me your valuable inputs
The idea behind Spring using RuntimeException is that generally there are different types of exception:
Exceptions that you want to recover from (such as a DuplicateKeyException if a record that you're trying to insert already exists or the more general DataIntegrityViolationException if there was a DB constraint that was violated as a result of user input)
Exceptions that you can't recover from (the database is down)
For the first case, you may well handle the exception (either through a custom business exception, so that the view layer can redirect to the input page and provide a meaningful message)
For the second case, it would be easier to let the exception bubble up and have it handled by a generic exception handler that then displays a generic error page to the user. For this scenario it doesn't make sense to wrap the exception in a custom exception as you won't be able to recover. A blown up DB tends to be fatal.
So what I would do:
try {
getHibernateTemplate().save(object);
} catch (DataIntegrityViolationException dive) {
throw new BusinessValidationException(dive, "You've got the data wrong");
}
Spring exception hierarchy is well documented.
Usually you can't do much if you have a data access exception, because in the working system this may be caused by the shortage of diskspace on the DB server, or network connection problems etc.
Such exceptions are usually need to be logged and investigated as soon as possible.
There some recoverable errors, they can be handled with spring exception hierarchy, but imho most of them should be avoided during the developing phase, so your web server should validate as many things as possible, before it goes to the db.
If you want to set the exception logging see the similar questions:
Exception handler in Spring MVC
Spring MVC Best Practice Handling Unrecoverable Exceptions In Controller
I am trying to show an custom error message on any occurrence of exception or error in my business layer. I am catching the exception in my controller and I would like to display it in my JSP.
This exception or error is not associated with any field in the screen, it's a pure server exception. I am also using an Annotated Controller. I am using Prototype for making AJAX requests to my controller.
In Spring you can register a HandlerExceptionResolver which will catch exceptions thrown by your Spring MVC controllers and forward them to the view layer for rendering. These are described in the Spring docs here. Start with the SimpleMappingExceptionResolver (see javadoc) which gives a simple mechanism for mapping exception types to views.
However, if the exception occurs outside if your Spring controller, for whatever reason, then you'll need a more generic fall-back solution, which involves configuring error pages in your web.xml file. This is not Spring-specific. See here for an example of how to do it.