Can someone help me out figuring why my #Around advice throws a Null Pointer Exception here. I have made sure that my advice returns an Object same as the method to proceed, yet I am getting the exception.
#Aspect
public class BasicAuthAspect
{
#Around("execution(* *..impl.PreferenceImpl.*(..))")
public Object auth(ProceedingJoinPoint joinPoint) {
log.debug("Inside Basic Auth check method..");
ServletRequestAttributes requestAttributes=null;
requestAttributes=(ServletRequestAttributes)
RequestContextHolder.getRequestAttributes();
if(requestAttributes!=null){
request =requestAttributes.getRequest();
Object[] signatureArgs = joinPoint.getArgs();
try {
return (Response) joinPoint.proceed(signatureArgs);
} catch (Throwable e) {
return Response.status(HttpStatus.SC_UNAUTHORIZED).build();
}
}
}
else{
return Response.status(HttpStatus.SC_UNAUTHORIZED).build();
}
}
}
Here is my method to proceed(PreferenceImpl.java):
#Override
public Response postPreferences( String preference) {
String responseReturned=searchDAO.postPreference( XSSUtils.normalize(preference));
if(responseReturned!=null)
response=Response.status("success").build();
else
response=Response.status("failure").build();
return response;
}
Here goes the error log:
java.lang.NullPointerException
at java.lang.String.<init>(String.java:556)[:1.7.0_80]
at org.apache.cxf.transport.http.AbstractHTTPDestination.getAuthorizationPolicyFromMessage(AbstractHTTPDestination.java:163)[173:org.apache.cxf.cxf-rt-transports-http:2.7.3]
at org.apache.cxf.transport.http.AbstractHTTPDestination.setupMessage(AbstractHTTPDestination.java:349)[173:org.apache.cxf.cxf-rt-transports-http:2.7.3]
at org.apache.cxf.transport.http.AbstractHTTPDestination.setupMessage(AbstractHTTPDestination.java:258)[173:org.apache.cxf.cxf-rt-transports-http:2.7.3]
at org.apache.cxf.transport.http_jetty.JettyHTTPDestination.serviceRequest(JettyHTTPDestination.java:345)[179:org.apache.cxf.cxf-rt-transports-http-jetty:2.7.3]
at org.apache.cxf.transport.http_jetty.JettyHTTPDestination.doService(JettyHTTPDestination.java:319)[179:org.apache.cxf.cxf-rt-transports-http-jetty:2.7.3]
at org.apache.cxf.transport.http_jetty.JettyHTTPHandler.handle(JettyHTTPHandler.java:72)[179:org.apache.cxf.cxf-rt-transports-http-jetty:2.7.3]
at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1040)[79:org.eclipse.jetty.server:7.6.8.v20121106]
at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:976)[79:org.eclipse.jetty.server:7.6.8.v20121106]
You could have several problems here:
Your pointcut intercepts all PreferenceImpl methods, but it seems you only want to catch a single one. I suggest you make the pointcut more specific.
You are assuming return type Response in the advice method, but your pointcut assumes * and the advice method itself returns Object, so theoretically another method could return another type and the cast would fail (see first problem).
You are trying to provide arguments to proceed(), but that is actually not necessary. So just remove the getArgs() stuff, you do not need it.
If despite my hints you still have problems, let me know and I can provide some sample code. BTW, maybe you want to read a basic Spring AOP tutorial. :-)
Related
I am using a Spring WebClient in a Kotlin project like this:
data class DTO(val name: String)
#Component
class Runner: ApplicationRunner
{
override fun run(args: ApplicationArguments?)
{
try
{
val dto = get<DTO>()
}
catch (e: Exception)
{
println("ERROR, all exceptions should have been caught in 'get' ")
}
}
}
inline private fun<reified TResult: Any> get(): TResult?
{
var result: TResult? = null
try
{
result = WebClient.create("https://maps.googleapis.com/maps/api/nonexisting")
.get()
.retrieve()
.bodyToMono<TResult>()
.block()
}
catch (e: Exception)
{
println("WORKS AS EXPECTED!!")
}
return result
}
The client will throw an exception, because the API will return a 404. However the exception is not caught where it should be, namely in the body of the get function, but it is propagated to the outer exception handler.
It is interesting to note that this happens only if the exception is thrown by the WebClient. If I replace the code in the try clause with a simple throw Exception("error"), the exception is caught where it should be.
Similarly, when I change the signature of get to a non-generic inline private fun get(): DTO? the problem also goes away.
For an exception to escape the try-catch block seems like a fundamental bug in the Kotlin tools. On the other hand, the fact that this happens only with the WebClient class indicates that this is a Spring problem. Or, it may be just me, using the tools in a wrong way.
I am really baffled here and have no idea how to proceed. Any ideas on why this might be happening are most welcome. Just for completeness, this is what it looks like in the debugger:
EDIT
The issue goes away after upgrading Spring Boot to 2.0.0.M6, it is still present in M5.
So it seems that this was a Spring issue and not a Kotlin issue. On the other hand it would be still nice to understand how a library that you include can seemingly cause the program to violate the laws of the programming language it is written in.
I tried the code with Spring Boot version 2.0.0.M5 and 2.0.0.M6, and it seems the behavior of the following block is different between those 2 versions:
result = WebClient.create("https://maps.googleapis.com/maps/api/nonexisting")
.get()
.retrieve()
.bodyToMono<TResult>()
.block()
somewhere along the chain, on Spring Boot 2.0.0.M5, the WebClientResponseException is returned, on Spring Boot 2.0.0.M6 it is thrown.
If you add a e.printStackTrace() to your outer catch, you will notice that the stack trace is:
java.lang.ClassCastException:
org.springframework.web.reactive.function.client.WebClientResponseException
cannot be cast to com.example.demo.DTO at
com.example.demo.Runner.run(Test.kt:18) at
org.springframework.boot.SpringApplication.callRunner(SpringApplication.java:780)
at
org.springframework.boot.SpringApplication.callRunners(SpringApplication.java:770)
at
org.springframework.boot.SpringApplication.afterRefresh(SpringApplication.java:760)
at
org.springframework.boot.SpringApplication.run(SpringApplication.java:328)
at
org.springframework.boot.SpringApplication.run(SpringApplication.java:1245)
at
org.springframework.boot.SpringApplication.run(SpringApplication.java:1233)
at com.example.demo.DemoApplicationKt.main(DemoApplication.kt:10)
So, actually, problem is, the returned WebClientResponseException is tried to be cast to DTO class on the moment of return of the call val dto = get<DTO>(). This means that, when you assign result = ..., there is no type checking done yet. So, if you change your code to, for example, call get<Object>() instead of get<DTO>(), it won't hit any catch blocks.
If you convert it to bytecode in IntelliJ Idea, and then decompile it to Java, you can see this block:
public class Runner implements ApplicationRunner {
public void run(#Nullable ApplicationArguments args) {
try {
Object result$iv = null;
try {
ResponseSpec $receiver$iv$iv = WebClient.create("https://maps.googleapis.com/maps/api/nonexisting").get().retrieve();
Mono var10000 = $receiver$iv$iv.bodyToMono((ParameterizedTypeReference)(new Runner$run$$inlined$get$1()));
Intrinsics.checkExpressionValueIsNotNull(var10000, "bodyToMono(object : Para…zedTypeReference<T>() {})");
result$iv = var10000.block();
} catch (Exception var7) {
String var5 = "WORKS AS EXPECTED!!";
System.out.println(var5);
}
DTO var2 = (DTO)result$iv;
} catch (Exception var8) {
String var3 = "ERROR, all exceptions should have been caught in 'get' ";
System.out.println(var3);
}
}
}
Here you can notice that casting to DTO is done on the point of method return (which is not a return anymore because it is inlined), after the inner catch block: DTO var2 = (DTO)result$iv;. It seems like that's the behavior for the inlined methods with reified type parameters.
This is due to SPR-16025 (see related commit) since the Kotlin extension is using internally the ParameterizedTypeReference variant, which has been fixed in Spring Framework 5.0.1, and transitively in Spring Boot 2.0.0.M6.
Note than if you use bodyToMono(TResult::class.java) with Spring Boot 2.0.0.M5, it will works as expected.
I am trying to log the exception in the spring boot based web service.
So I have used GlobalExceptionHandler
My code :
#ControllerAdvice
#RestController
public class GlobalExceptionHandler {
#ResponseStatus(HttpStatus.INTERNAL_SERVER_ERROR)
#ExceptionHandler(value = Exception.class)
public String handleException(Exception e){
System.out.println("Ankit == "+e.getMessage());
StringWriter errors = new StringWriter();
e.printStackTrace(new PrintWriter(errors));
System.out.println(errors.toString());
return e.getMessage();
}
}
the code is working fine. What I want is exception details. I mean the code where the exception occurs? File name / line ? or do I have to parse the stacktrace? I mean spring boot must have thought something for this?
Using IDE
If you are using any IDE then go to Console Window.
Clear console
Repeat action that causes Exception
Search in Console (CTRL + F) for ERROR
Look for line above(Look for 2-3 lines if you don't find immediate above) the line which contains ERROR. This line has details of Class, Method where Exception has occurred.
Without looking at Console or Logs
If you want to use it in production then, handling atleast known exceptions(like BAD_REQUEST, NOT_FOUND etc.) the way it is done below might be helpful (adding an extra parameter to Exception Class) :
Employee employee = employeeService.getEmployeeById(employeeId);
if (null == employee) {
logger.error("No tenant exists for employeeId:"+employeeId);
throw new ObjectNotFoundException("Emplyee Not Found", this.getClass().getSimpleName();));
}
here this.getClass().getSimpleName(); will be passed as parameter from EmployeeController class. So in ObjectNotFoundException we can add a parameter ClassName and When you handle it in GlobalExceptionHandler, you can do it as it is done below,
#ControllerAdvice
#RestController
public class GlobalExceptionHandler {
#ResponseStatus(HttpStatus.INTERNAL_SERVER_ERROR)
#ExceptionHandler(value = Exception.class)
public String handleException(Exception e){
System.out.println("Ankit == "+e.getMessage());
StringWriter errors = new StringWriter();
e.printStackTrace(new PrintWriter(errors));
String classWithExceptionName = e.getClassName();
// you need to add this above getter method to your Exception Class
System.out.println(errors.toString());
return e.getMessage();
}
}
This is for known common exceptions. We need to add extra parameter(ClassName) to All Custom Exceptions that you are throwing and that might be little extra code but i think that is the way. Hope it helps now.
Is there a way to get the reason a HystrixCommand failed when using the #HystrixCommand annotation within a Spring Boot application? It looks like if you implement your own HystrixCommand, you have access to the getFailedExecutionException but how can you get access to this when using the annotation? I would like to be able to do different things in the fallback method based on the type of exception that occurred. Is this possible?
I saw a note about HystrixRequestContext.initializeContext() but the HystrixRequestContext doesn't give you access to anything, is there a different way to use that context to get access to the exceptions?
Simply add a Throwable parameter to the fallback method and it will receive the exception which the original command produced.
From https://github.com/Netflix/Hystrix/tree/master/hystrix-contrib/hystrix-javanica
#HystrixCommand(fallbackMethod = "fallback1")
User getUserById(String id) {
throw new RuntimeException("getUserById command failed");
}
#HystrixCommand(fallbackMethod = "fallback2")
User fallback1(String id, Throwable e) {
assert "getUserById command failed".equals(e.getMessage());
throw new RuntimeException("fallback1 failed");
}
I haven't found a way to get the exception with Annotations either, but creating my own Command worked for me like so:
public static class DemoCommand extends HystrixCommand<String> {
protected DemoCommand() {
super(HystrixCommandGroupKey.Factory.asKey("Demo"));
}
#Override
protected String run() throws Exception {
throw new RuntimeException("failed!");
}
#Override
protected String getFallback() {
System.out.println("Events (so far) in Fallback: " + getExecutionEvents());
return getFailedExecutionException().getMessage();
}
}
Hopefully this helps someone else as well.
As said in the documentation Hystrix-documentation getFallback() method will be thrown when:
Whenever a command execution fails: when an exception is thrown by construct() or run()
When the command is short-circuited because the circuit is open
When the command’s thread pool and queue or semaphore are at capacity
When the command has exceeded its timeout length.
So you can easily get what raised your fallback method called by assigning the the execution exception to a Throwable object.
Assuming your HystrixCommand returns a String
public class ExampleTask extends HystrixCommand<String> {
//Your class body
}
do as follows:
#Override
protected ErrorCodes getFallback() {
Throwable t = getExecutionException();
if (circuitBreaker.isOpen()) {
// Log or something
} else if (t instanceof RejectedExecutionException) {
// Log and get the threadpool name, could be useful
} else {
// Maybe something else happened
}
return "A default String"; // Avoid using any HTTP request or ypu will need to wrap it also in HystrixCommand
}
More info here
I couldn't find a way to obtain the exception with the annotations, but i found HystrixPlugins , with that you can register a HystrixCommandExecutionHook and you can get the exact exception in that like this :
HystrixPlugins.getInstance().registerCommandExecutionHook(new HystrixCommandExecutionHook() {
#Override
public <T> void onFallbackStart(final HystrixInvokable<T> commandInstance) {
}
});
The command instance is a GenericCommand.
Most of the time just using getFailedExecutionException().getMessage() gave me null values.
Exception errorFromThrowable = getExceptionFromThrowable(getExecutionException());
String errMessage = (errorFromThrowable != null) ? errorFromThrowable.getMessage()
this gives me better results all the time.
I am using #ControllerAdvice annotation for defining exceptions at application level. Now the problem is I am having two #ControllerAdvice classes, one for REST and one for the normal web app. When I define #ExceptionHandler for Exception.class in both, only the first one is considered. How do I separate both? Or how can I catch an Exception and determine from where it has occured? Is there a way or else do I need to use controller-specific exception handlers?
I resolved this issue by creating a custom exceptions for my application and giving one exception handler method for each of them with #exception handler.
I also used aspects to make sure that every exception is converted to any of the custom exceptions.
#Aspect
#Component
public class ExceptionInterceptor {
#AfterThrowing(pointcut = "within(x.y.package..*)", throwing = "t")
public void toRuntimeException(Throwable t)
throws ApplicationException1, ApplicationException2,ApplicationException3 {
if (t instanceof ApplicationException1) {
throw (ApplicationException1) t;
} else if (t instanceof ApplicationException2) {
throw (ApplicationException2) t;
} else
throw (ApplicationException3) t;
}
}
These will transfer control to #controlleradvice.
I noticed this have been left for a month or so, so it might be old. But this article may help http://www.baeldung.com/2013/01/31/exception-handling-for-rest-with-spring-3-2/.
The section 3.5 is probably what you are looking for, a custom Exception Resolver.
Is it possible to have two AfterThrows pieces of advice be applied to the same pointcut restricted by specific Exception type where one exception is a superclass of the other with, in the case of the subclass being captured, only one advice being executed?
I want to translate runtime exceptions (both custom and standard java ones) being chucked out of a service layer, where I do some specific translation in certain cases and then have a catch-all type piece of advice to translate anything truly unexpected:
#AfterThrowing(pointcut = "execution(* com.my.company.api.*(..))", throwing = "rnfex")
public void doTranslationAction(ResourceNotFoundException rnfex) {
// throw new WebApplicationException with Status.NOT_FOUND;
}
#AfterThrowing(pointcut = "execution(* com.my.company.api.*(..))", throwing = "aex")
public void doTranslationAction(AuthorisationException aex) {
// throw new WebApplicationException with Status.NOT_AUTHORISED;
}
#AfterThrowing(pointcut = "execution(* com.my.company.api.*(..))", throwing = "throwable")
public void doTranslationAction(Throwable throwable) {
// Log something here about this unexpected exception
// throw new WebApplicationException with Status.INTERNAL_SERVER_ERROR
}
I find that in this case, if I throw an exception which is explicitly catered for then the correct method is called, a translated exception is thrown, which is then captured by the broader 'Throwable' advice, then translated again into the catch-all INTERNAL_SERVER_ERROR WAE. This isn't unexpected, but just not quite what I was looking for.
To get around this I've got a single piece of advice which captures all Throwable types and then uses 'instanceof' to decide whether this is an expected custom runtime exception that I can translate into a specific WAE or not.
If I ever see 'instanceof' I'm sure I've done something to be ashamed of, but I'm not sure if there's a better way of solving this problemette without it?
I'm also against converting my expected custom exceptions to checked exceptions and then catching Runtime exception as the catch all, which could be one solution.
I wrote a similar aspect a while ago and I ended up using "instance of". I don't think there's a problem with that.
i am not pretty sure... but just wondering whether your last(third) advice can be written in the below fashion
execution( * com.my.company.api..*(..)) and !execution( * com.my.company.api.XyzAspect..*(..))
public void doTranslationAction(Throwable throwable) {
// Log something here about this unexpected exception
// throw new WebApplicationException with Status.INTERNAL_SERVER_ERROR
}
where XyzAspect.java is the #Aspect class where in you are writing these 3 advices.