Im creating a dead letter channel errorhandler like below
errorHandler(deadLetterChannel("direct:myDLC").useOriginalMessage().maximumRedeliveries(1));
from("direct:myDLC")
.bean(MyErrorProcessor.class);
The Bean MyErrorProcessor should be able to handle all types of checked and unchecked exceptions like below..
public void process(Exchange exchange) throws Exception {
Exception e=(Exception)exchange.getProperty(Exchange.EXCEPTION_CAUGHT, Exception.class);
e.printStackTrace();
if(e instanceof MyUncheckedException){
logger.error("MyUncheckedException: "+((MyException) e).getErrorCode()+" : "+((MyException) e).getErrorDesc());
}else if(e instanceof MyException){
logger.error("MyException: "+((MyException) e).getErrorCode()+" : "+((MyException) e).getErrorDesc());
}
}
But after exception is handled the original message should be redirected to route's endpoint.. how to continue route once exception handled like this??
Using continued() will work, it will ignore the error and continue to process, so then you would probably want to handle the specific Exception
see http://camel.apache.org/exception-clause.html
onException(MyException.class)
.continued(true)
;
If you would use .useOriginalMessage() on this exception handling, the original message would be the message that is continued.
Related
I'm still learning Kotlin and I just learned about the "use" and how it is a replacement for a try, catch and finally block.
However I am curious if it is possible to customize it's exception handling for example:
var connection: Connection? = null
try {
connection = dataSource.connection
connection.prepareStatement(query).execute()
} catch (e: SQLException) {
logger.log("Specific error for that query")
e.printStackTrace()
} finally {
if (connection != null && !connection.isClosed) {
connection.close()
}
}
That code is my current one, I have a specific error I would like to display on the catch, would that be possible using use?
This is my current use code:
dataSource.connection.use { connection ->
connection.prepareStatement(query).execute()
}
As commented by #Tenfour04, and from the documentation
[use] Executes the given block function on this resource and then closes it down correctly whether an exception is thrown or not.
In particular it is implemented like this:
public inline fun <T : AutoCloseable?, R> T.use(block: (T) -> R): R {
var exception: Throwable? = null
try {
return block(this)
} catch (e: Throwable) {
exception = e
throw e
} finally {
this.closeFinally(exception)
}
}
That piece of code should look familiar if you're a Java developer, but basically it executes block passing this (i.e. the receiver object) as an argument to your block of code. At the end it closes the AutoCloseable resource. If at any point an exception is thrown (either inside block or while closing the resource), that exception is thrown back to the caller, i.e. your code.
As an edge case you could have 2 exceptions, one when executing block and one when closing the resource. This is handled by closeFinally (whose source is available in the same file linked above) and the exception thrown while closing the resource is added as a suppressed exception to the one thrown from block – that's because only up to 1 exception can be thrown by a method, so they had to choose which one to throw. The same actually applies to the try-with-resources statement in Java.
I found there is an old issue Sleuth/Zipkin tracing with #ControllerAdvice, but I meet the same problem with the latest version(spring-cloud-starter-zipkin:2.1.0.RELEASE), I debug it and find that the error is null, so zipkin just guess with statuscode. I have to throw the exception again to make zipkin notify the exception
error is null
zipkin result
ControllerAdvice
throw the exception again, it works
It makes perfect sense that it's null. That's because YOU control the way what happens with the caught exception. In your case, nothing, cause you swallow that exception.
If you want to do sth better, just add the error tag manually via the SpanCustomizer. That way you'll add the exception to the given span. It will then automatically get closed and reported to Zipkin (you can do sth else than ex.toString() of course.
#Slf4j
#RestControllerAdvice
#Order(Ordered.HIGHEST_PRECEDENCE)
public class ExceptionHanders {
private final SpanCustomizer customizer;
public ExceptionHanders(SpanCustomizer customizer) {
this.customizer = customizer;
}
#ExceptionHandler({RuntimeException.class})
#ResponseStatus(HttpStatus.INTERNAL_SERVER_ERROR)
public String handleRuntimeException(Exception ex) throws Exception {
this.customizer.tag("error", ex.toString());
return "testabcd";
}
}
I need to return the message from a thrown exception, or put it in the outmessage. But it does not print the correct message on the frontend.
The camel docs suggest using .transform(simple?...) .handled(true) but most of it is deprecated.
What's the correct way of doing this?
Response:
<418 I'm a teapot,simple{${exception.message}},{}>
Route
from("direct:csv")
.doTry()
.process(doSomeThingWithTheFileProcessor)
.doCatch(Exception.class)
.process(e -> {
e.getOut().setBody(new ResponseEntity<String>(exceptionMessage().toString(), HttpStatus.I_AM_A_TEAPOT));
}).stop()
.end()
.process(finalizeTheRouteProcessor);
doSomethingWithFileProcessor
public void process(Exchange exchange) throws Exception {
String filename = exchange.getIn().getHeader("CamelFileName", String.class);
MyFile mf = repo.getFile(filename); //throws exception
exchange.getOut().setBody(exchange.getIn().getBody());
exchange.getOut().setHeader("CamelFileName", exchange.getIn().getHeader("CamelFileName"));
}
There is a lot of ways how to do it. All of it is correct, choose your favourite depending on complexity of error handling. I have published examples in this gist. None of it is deprecated in Camel version 2.22.0.
With Processor
from("direct:withProcessor")
.doTry()
.process(new ThrowExceptionProcessor())
.doCatch(Exception.class)
.process(new Processor() {
#Override
public void process(Exchange exchange) throws Exception {
final Throwable ex = exchange.getProperty(Exchange.EXCEPTION_CAUGHT, Throwable.class);
exchange.getIn().setBody(ex.getMessage());
}
})
.end();
With Simple language
from("direct:withSimple")
.doTry()
.process(new ThrowExceptionProcessor())
.doCatch(Exception.class)
.transform().simple("${exception.message}")
.end();
With setBody
from("direct:withValueBuilder")
.doTry()
.process(new ThrowExceptionProcessor())
.doCatch(Exception.class)
.setBody(exceptionMessage())
.end();
In the doCatch() Camel moves the exception into a property on the exchange with the key Exchange.EXCEPTION_CAUGHT (http://camel.apache.org/why-is-the-exception-null-when-i-use-onexception.html).
So you can use
e.getOut().setBody(new ResponseEntity<String>(e.getProperty(Exchange.EXCEPTION_CAUGHT, Exception.class).getMessage(), HttpStatus.OK));
I am trying to handle the exception produced by Javaparser library due to token error. I used the following code.
String content=getTheSource();
ByteArrayInputStream bin=new ByteArrayInputStream(content.getBytes());
try
{
CompilationUnit cu=JavaParser.parse(bin);
} catch (Exception e) {
// TODO Auto-generated catch block
//e.printStackTrace();
//my handling code here
}finally{
bin.close();
}
However, the exception was never caught and I am getting a different exception generated from somewhere else. I got this exception:
Exception in thread "main" japa.parser.TokenMgrError: Lexical error at line 1, column 16. Encountered: "#" (35), after : ""
at japa.parser.ASTParserTokenManager.getNextToken(ASTParserTokenManager.java:2247)
at japa.parser.ASTParser.jj_ntk(ASTParser.java:9986)
at japa.parser.ASTParser.ClassOrInterfaceBody(ASTParser.java:926)
at japa.parser.ASTParser.ClassOrInterfaceDeclaration(ASTParser.java:604)
at japa.parser.ASTParser.TypeDeclaration(ASTParser.java:524)
at japa.parser.ASTParser.CompilationUnit(ASTParser.java:269)
at japa.parser.JavaParser.parse(JavaParser.java:81)
at japa.parser.JavaParser.parse(JavaParser.java:94)
at misc.CompileTest.main(CompileTest.java:45)
Any idea, how to handle the exception? Thanks in advance
As the name indicates, TokenMgrError is an error. So you have to catch an Error instead of Exception. If you want to catch both Error and Exception, you can use Throwable instead.
Originally, this error is throwed by JavaCC (TokenMgrError) which is used by Javaparser.
From version 3 on, JavaParser will/should not throw this error anymore.
We are using Enterprise Library for all our logging and exception handling needs in our app. We have added an email listener to send all the caught exceptions in email to the administrator. One requirement is that when an exception occurs in a method we need to retrieve the parameter values of the method if any and attach it to the exception details in the email sent. Is it possible without writing a custom logger?
Just create a custom exception, setting the message to the parameters:
try {
...
} catch(Exception ex) {
var customException = new CustomException(ex, string.format("Param1 {0}, Param2 {1}", param1, param2));
bool rethrow = ExceptionPolicy.HandleException(customException, PolicyName);
}
verified that in fact the ExceptionFormatter class will indeed traverse all inner exceptions, so your CustomException could be as simple as
public class CustomException : Exception
{
public CustomException(string message, Exception innerException) : base(message, innerException)
{
}
}