I am using Apache Velocity to create html pages but I am getting an exception while initializing.
Properties p = new Properties();
String path = EmpowERPlugin.getPluginDir()+IEIFileConstants.VELOCITY_PATH;
p.setProperty("resource.loader","file");
p.setProperty("file.resource.loader.path", path);
//p.setProperty ("runtime.log.logsystem.class","org.apache.velocity.runtime.log.NullLogSystem");
p.setProperty("class.resource.loader.class", "org.apache.velocity.runtime.resource.loader.FileResourceLoader");
try{
Velocity.init(p);
}catch(VelocityException e){
e.printStackTrace();
}catch(Exception e1){
e1.printStackTrace()
}finally{
//some code
}
while executing Velocity.init() the control directly goes to the finally block instead of catch, so I am not able to guess what type of exception it is
Exception class isn't catching all possible exceptions although its tricky name:
The class Exception and any subclasses that are not also subclasses of RuntimeException are checked exceptions.
I suggest in your case to catch the superclass Throwable:
The Throwable class is the superclass of all errors and exceptions in the Java language.
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'm trying to use the inline function use with a FileInputStream instead of the classic try/catch IOException so that
try {
val is = FileInputStream(file)
// file handling...
}
catch (e: IOException) {
e.printStackTrace()
}
becomes
FileInputStream(file).use { fis ->
// do stuff with file
}
My question is, why use the function use if it stills throws exception? Do I have to wrap use in a try/catch? This seems ridiculous.
From Kotlin documentation:
Executes the given block function on this resource and then closes it
down correctly whether an exception is thrown or not.
When you use an object that implements the Closeable interface, you need to call the close() method when you are done with it, so it releases any system resources associated with the object.
You need to be careful and close it even when an exception is thrown. In this kind of situation that is error prone, cause you might not know or forget to handle it properly, it is better to automate this pattern. That's exactly what the use function does.
Your try-catch does not close the resource so you are comparing apples to oranges. If you close the resource in finally block:
val is = FileInputStream(file)
try {
...
}
catch (e: IOException) {
...
}
finally {
is.close()
}
is definitely more verbose than use which handles closing the resource.
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'm developing an application using Play 2.3.1.
I'm annotating all my controllers with the following Action :
#Override
public Promise<Result> call(final Context ctx) throws Throwable {
try {
return delegate.call(ctx);
} catch (MyCustomException e) {
return handleCustomException(e);
} catch (Exception e) {
return handleUnexpectedError(e);
}
}
The aim of this action is to catch any exception thrown by a controller method in order to send a clean message to the user.
MyCustomException is my application specific exception that extends Exception.
The problem is that even if I throw a MyCustomException in the method of my controller, the corresponding catch statement is never executed.
I always have a RuntimeException caused by my MyCustomException.
The consequence is that no matter what exception occured, the user always sees the result sent by handleUnexpectedError(e).
What am I doing wrong ? Thanks.
After some investigation, the guilty is the Security action of Play.
More details here : https://groups.google.com/forum/#!topic/play-framework/AY4NuQziYyM
Because I added my custom actions at AbstractController level and the #Authenticated(Authenticator.class) annotation at the controller level, the security action composition is the last one to be executed.
Because of the Security.java at line 51, even if my exception is expected, Play throws a RuntimeException.
So the solution is to add the security annotation at method level in order to be sure that it is executed before the first execution of the method.
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)
{
}
}