Anyway, here is the message I originally posted to the user group:
-------- Doorgestuurd bericht --------
Onderwerp: Builder for FileAppender
Datum: Wed, 12 Aug 2015 18:42:04 +0200
Van: Xen <x...@dds.nl>
Aan: log4j-u...@logging.apache.org
Hi,
I decided it would be fun and educational to try to write a builder for
the FileAppender, seeing as it is not there. Perhaps this ought to go to
the dev list, but that is rather high volume :-/.
And maybe you want this as a Jira ticket, but that is rather odd
communicating I feel.
The FileAppender has an issue with creating a builder:
- the create method takes only Strings and a few objects.
- the real constructor takes regular parameters.
- this is equivalent for ConsoleAppender.Builder
- the create method performs sanity checks and logs error messages and
returns if conditions are not met with a null.
- the same is true for ConsoleAppender.Builder, but it just skips those
and calls the constructor directlty.
- were I to create a builder I would follow the example of the
ConsoleAppender and not replicate/duplicate the code that does all the
checks however this can result in erroneous application.
- ideally you would refactor the sanity checks into a different method
(it operates on the parsed values (Strings) anyway) since you now have
two (equivalent) ways of constructing the object
- I will do so for good day's fortune's sake anyway.
- the sanity checks may change one of the parameters, a boolean. To do
it with a central method would require
e.g.*org.apache.commons.lang.mutable.MutableBoolean* to be passed along
(or an equivalent, could be an inner class) and I don't know how hideous
you'd consider that.
- essentially the create method *could* use the builder, but if the
builder used the create, it would have to convert all the booleans back
to string, where they are converted to boolean again.
I've completed the rewrite. My application still works and the unit test
that was already there for FileAppender succeeds:
-------------------------------------------------------
T E S T S
-------------------------------------------------------
Running org.apache.logging.log4j.core.appender.FileAppenderTest
Tests run: 6, Failures: 0, Errors: 0, Skipped: 1, Time elapsed: 4.713
sec - in org.apache.logging.log4j.core.appender.FileAppenderTest
Results :
Tests run: 6, Failures: 0, Errors: 0, Skipped: 1
[INFO]
------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO]
------------------------------------------------------------------------
[INFO] Total time: 01:18 min
[INFO] Finished at: 2015-08-12T17:59:18+02:00
[INFO] Final Memory: 22M/336M
[INFO]
------------------------------------------------------------------------
But then, I haven't used the builder yet.
Now that I have, it works. However the status logger messages given from
these classes don't work:
System.setProperty("org.apache.logging.log4j.simplelog.StatusLogger.level",
"WARN");
// adds a logger / appender that should generate an error message
Output:
WARN StatusLogger Multiple logging implementations found:
Factory: org.apache.logging.log4j.core.impl.Log4jContextFactory,
Weighting: 10
Using factory: org.apache.logging.log4j.core.impl.Log4jContextFactory
Exception in thread "main" java.lang.NullPointerException
at thunderbolt.log.Logging.init(Logging.java:87)
at thunderbolt.Server.main(Server.java:230)
The NullPointerException is completely expected as the method returned
NULL due to a required parameter missing. I just failed to supply a
filename. A quick interjected System.out message proves it:
WARN StatusLogger Multiple logging implementations found:
Factory: org.apache.logging.log4j.core.impl.Log4jContextFactory,
Weighting: 10
Using factory: org.apache.logging.log4j.core.impl.Log4jContextFactory
*Trying to write output error message: .....**
*Exception in thread "main" java.lang.NullPointerException
at thunderbolt.log.Logging.init(Logging.java:87)
at thunderbolt.Server.main(Server.java:230)
*Should I post a JIRA of this as a separate issue?.*
I have a working modified FileAppender that can use the Builder Paradigm
to construct the object and it is working. I could write/extend the unit
test for FileAppender (FileAppenderTest) to account for it and post a
dual update as a Jira ticket/patch. The code might not be pretty
according to your standards but I've done my best to single out the
sanity checks in accordance with a mutable boolean object/class. I have
replicated and mirrored the ConsoleAppender in this as much as possible,
the code for the builder follows the same style and annotations.
Essentially the create method could use the builder without any problem.
It's just that it would/might need to use all of the methods, devoiding
the benefit/idea of using a builder. You could rewrite it to only use
the methods for parameters that are not null/invalid. Then the builder
could handly sanity and error messages. It would not be all that ugly
and probably not uglier than what I have now, but at this point I have a
centralized sanity checking function.
Let me know if you want to see the source or you want a diff our you
want a Jira ticket with a diff.
Regards, Bart.
-----------------------------------------------
Anyway I'm holding silence for a while, going to do some other things I
guess.
Maybe commit suicide ;-). By not eating lol. May take me a while. Maybe
I should start smoking, that should help.
Regards..
