Editing Loggifier.unkrig.de

== Getting started with LOGGIFIER ==

Now you want to know how you can use the LOGGIFIER. I presume that you know what java.util.logging is and why you want
to use logging at all (e.g. in favor of an interactive debugger).

So let's start with a very simple program:

    '''import''' java.util.logging.Logger;
    
    '''public class''' Main {
    
        '''private static final''' Logger LOGGER = Logger.getLogger("Main.USER");
    
        '''public static void''' main(String[] args) {
            System.out.println("HELLO WORLD");
            LOGGER.fine("About to terminate");
        }
    }

By default, java.util.logging is disabled, so we won't get any logging output:

    '''$ javac Main.java'''
    '''$ java Main'''
    HELLO WORLD
    '''$'''

Thus we need to create one more file

    # File 'my_logging.properties'.
    handlers = java.util.logging.ConsoleHandler
    java.util.logging.ConsoleHandler.level = FINEST
    .level = FINEST

, and run our program with the 'java.util.logging.config.file' system property set:

    '''$ java -Djava.util.logging.config.file=my_logging.properties Main'''
    HELLO WORLD
    26.08.2011 11:01:53 Main main
    FINE: About to terminate
    '''$'''

(If you don't like the two-line output format, then you can configure a different log formatter, e.g.
'de.unkrig.commons.util.logging.formatter.PrintfFormatter', contained in [http://loggifier.unkrig.de/download/ de.unkrig.commons.jar], in the 'my_logging.properties' file:

    java.util.logging.ConsoleHandler.formatter = de.unkrig.commons.util.logging.formatter.PrintfFormatter
    de.unkrig.commons.util.logging.formatter.PrintfFormatter.format = COMPACT

Then you'll get:

    '''$ java -Djava.util.logging.config.file=my_logging.properties -cp de.unkrig.commons.jar\;. Main'''
    HELLO WORLD
    FINE Main::main About to terminate
    '''$'''

But that's only a matter of taste.)

So now let's loggify the 'Main' class! Get 'de.unkrig.loggifier.jar' and 'de.unkrig.loggifier-runtime.jar' from [http://loggifier.unkrig.de/download/] and run:

    '''$ ls -l'''
    -rwx------+ 1 H7DA016 Kein 969 Aug 26 11:23 Main.class
    '''$ java -cp de.unkrig.loggifier.jar de.unkrig.loggifier.Main Main.class'''
    '''$ ls -l'''
    -rwx------+ 1 H7DA016 Kein 2314 Aug 26 11:23 Main.class
    '''$'''

Not only can you pass class files to LOGGIFER, but also directories, files in ZIP format that contain '.class' files
(e.g. JAR and WAR files), and even ZIP files that contain nested ZIP files with '.class' files (e.g. EAR files). In
any case, LOGGIFIER will modify the contained '.class' "in-place".

Now what logging do we get now?

    '''$ java -Djava.util.logging.config.file=my_logging.properties -cp de.unkrig.commons.jar\;de.unkrig.loggifier-runtime.jar\;. Main'''
    FINER Main::<clinit>() (Main.java:5) ENTRY  args=()
    FINER Main::<clinit>() (Main.java:5) RETURN
    FINER Main::main(String[]) (Main.java:8) ENTRY  args=(String[0])
    HELLO WORLD
    FINE Main::main About to terminate
    FINER Main::main(String[]) (Main.java:10) RETURN
    '''$'''

Notice that you now need to have the (very small) 'de.unkrig.loggifier-runtime.jar' on the class path, because the
injected logging code needs that.

By default, LOGGIFIER injects a 'reasonable' amount of logging: You can see how the class initializer of the 'Main'
class is executed, then how the 'main()' method is executed. Notice how the hand-written logging seamlessly mixes with
the automatically injected logging.

Effectively, we can now remove the hand-written logging code from our class, because the automatically injected logging
code now does the job:

    '''public class''' Main {
    
        '''public static void''' main(String[] args) {
            System.out.println("HELLO WORLD");
        }
    }

Now let's compile, loggify and run again:

    '''$ javac Main.java'''
    '''$ java -cp de.unkrig.loggifier.jar de.unkrig.loggifier.Main Main.class'''
    '''$ java -Djava.util.logging.config.file=my_logging.properties -cp de.unkrig.commons.jar\;de.unkrig.loggifier-runtime.jar\;. Main'''
    FINER Main::<clinit>() (Main.java:5) ENTRY  args=()
    FINER Main::<clinit>() (Main.java:5) RETURN
    FINER Main::main(String[]) (Main.java:8) ENTRY  args=(String[0])
    HELLO WORLD
    FINER Main::main(String[]) (Main.java:10) RETURN
    '''$'''

For demonstration, we now set the amount of logging to the highest possible level. There are several ways to configure
the injection of logging code: We can pass a 'rule' to the LOGGIFER like '-rule ALL=FINE', or add a '@Loggify'
annotation to any class or method declaration:

    import de.unkrig.loggifier.runtime.annotation.Loggify;
    
    @Loggify("ALL=FINE")
    public class Main {
        // ...

Then compile, loggify and run again:

    '''$ javac Main.java -cp de.unkrig.loggifier-runtime.jar'''
    '''$ java -cp de.unkrig.loggifier.jar de.unkrig.loggifier.Main Main.class'''
    '''$ java -Djava.util.logging.config.file=my_logging.properties -cp de.unkrig.loggifier-runtime.jar\;de.unkrig.commons.jar\;. Main'''
    FINE Main::<clinit>() (Main.java:1) CLINIT Main
    FINE Main::<clinit>() (Main.java:7) ENTRY  args=()
    FINE Main::<clinit>() (Main.java:7) CONST  "Main.USER"
    FINE Main::<clinit>() (Main.java:7) INVOKE Logger.getLogger(String): args=("Main.USER")
    FINE Main::<clinit>() (Main.java:7) RESULT Logger.getLogger(String) => java.util.logging.Logger@156ee8e
    FINE Main::<clinit>() (Main.java:7) PUT    Main.LOGGER <== java.util.logging.Logger@156ee8e
    FINE Main::<clinit>() (Main.java:7) RETURN
    FINE Main::main(String[]) (Main.java:10) ENTRY  args=(String[0])
    FINE Main::main(String[]) (Main.java:10) GET    System.out ==> java.io.PrintStream@47b480
    FINE Main::main(String[]) (Main.java:10) CONST  "HELLO WORLD"
    FINE Main::main(String[]) (Main.java:10) INVOKE PrintStream.println(String): target=java.io.PrintStream@47b480, args=("HELLO WORLD")
    HELLO WORLD
    FINE Main::main(String[]) (Main.java:10) RESULT PrintStream.println(String)
    FINE Main::main(String[]) (Main.java:12) RETURN
    '''$'''

(Notice that JAVAC now needs "de.unkrig.loggifier-runtime.jar" on the class path, because "@de.unkrig.loggifier.runtime.annotation.Loggify" lives there.)

Now you also get informed how the 'System.out' field is read and the string constant "HELLO WORLD" is used - if
you're interested.

LOGGIFIER is not only available as a command-line tool, but also as an ECLIPSE plug-in and an ANT task.