Ok, It took me about a day but I've finally got the show on the road. My
custom priorities _are_ working using the DOMConfigurator. Some comments
regarding my experiences from which others might be able to benifit:
- I got a bit mislead by all the remarks on Jim's example, but the example
works fine and allows to configure logging per category, without the need
for factories. You also do not need to configure each category in your xml
fine. In short everything works fine with Jim's example and the comments on
it are for advanced users.
- I think the standard xml example in log4j should also contain a priority
larger than FATAL, eg. ALWAYS, because now users might get confused and
think that you can only define priorities lower than DEBUG.
- A word of caution: when redefining the logging for a category in the XML
file, DO NOT forget to specify your priority class because otherwise it will
seem as if log4j is not working correctly (it took me about two hours before
I realized my mistake)
<category name="com.eic.computation.MeanDeviation">
<priority value="debug" CLASS="com.eic.util.logging.EicPriority" />
</category>
- I am not in favour of doing configuration using XML files, so I am looking
forward to the time Simon's patch will be added to an official log4j
release. Hopefully the patch will work via the AbstractFactory pattern.
- It would be nice to have the DOMConfigurator support variables like the
PropertyConfigurator does, ie. ${SOME_PROPERTY}
- I had some problems to use the DOMConfigurator even if not using custom
priorities, but it is not that hard really. It's a pitty though that XML
parsers only accept real files, ie.
InputStream is = new SomeClass().getClass().getResourceAsStream("my file");
DOMConfigurator(is, new Factory());
doesn't work. It took me a while to figure that out because what I would
have liked was that the config file was read in from the classpath via
getResourceAsStream(), but it just couldn't get it working. What I do now is
just pass the location of log4j config file in the args[] of the main method
what actually comes down to:
DomConfigurator.configure("c:\somedir\anotherdir\log4j.xml");
> -----Original Message-----
> From: Jim Moore [mailto:[EMAIL PROTECTED]]
> Sent: Thursday, February 15, 2001 5:01 PM
> To: 'LOG4J Users Mailing List'
> Subject: RE: adding custom priorities
>
>
> There is no way to use a custom Priority when using the
> PropertyConfigurator. Major bummer, I know, because that's
> certainly more
> straightforward than DOMConfigurator to use. The format of
> the XML for
> DOMConfigurator is easy (if you know XML), but it's a bit of
> a pain to have
> to include the extra libraries.
>
> Other than that, the code below should give you a good
> example of how to
> address your other concerns:
>
> /**
> * Provides support for the {@link TraceablePriority.TRACE} priority.
> */
> public class TraceableCategory extends Category {
> private static final Factory factory = new Factory();
> private static final String instanceFQCN =
> TraceableCategory.class.getName();
>
> public TraceableCategory(String name) {
> super(name);
> }
>
> /**
> * This method overrides {@link
> Category#getInstance(String)} by supplying
> * its own factory type as a parameter.
> */
> public static Category getInstance(String name) {
> return Category.getInstance(name, factory);
> }
>
> /**
> * This method overrides {@link
> Category#getInstance(String)} by supplying
> * its own factory type as a parameter.
> */
> public static Category getInstance(Class cls) {
> return Category.getInstance(cls.getName(), factory);
> }
>
> /**
> * Log a message object with the {@link
> TraceablePriority#TRACE TRACE}
> * priority.<p>
> *
> * This method first checks if this category is <code>TRACE</code>
> * enabled by comparing the priority of this category
> with the {@link
> * TraceablePriority#TRACE TRACE} priority. If this category is
> * <code>TRACE</code> enabled, then it converts the message object
> * (passed as parameter) to a string by invoking the appropriate
> * {@link ObjectRenderer}. It then proceeds to call all the
> * registered appenders in this category and also higher in the
> * hierarchy depending on the value of the additivity flag.
> *
> * @param message the message object to log.
> */
> public void trace(String message) {
> if (isTraceEnabled())
> callAppenders(new LoggingEvent(instanceFQCN, this,
> TraceablePriority.TRACE,
> message, null));
> }
>
> /**
> * Check whether this category is enabled for the <code>TRACE</code>
> * priority.<p>
> *
> * This function is intended to lessen the computational cost of
> * disabled log trace statements.<p>
> *
> * For some <code>cat</code> Category object, when you write,
> * <pre>
> * cat.trace("This is entry number: " + i );
> * </pre>
> *
> * You incur the cost constructing the message, concatenatiion in
> * this case, regardless of whether the message is logged or not.<p>
> *
> * If you are worried about speed, then you should write
> * <pre>
> * if(cat.isTraceEnabled()) {
> * cat.trace("This is entry number: " + i );
> * }
> * </pre>
> *
> * This way you will not incur the cost of parameter construction
> * if tracing is disabled for <code>cat</code>. On the other hand,
> * if the <code>cat</code> is trace enabled, you will incur the cost
> * of evaluating whether the category is trace enabled twice. Once
> * in <code>isTraceEnabled</code> and once in the
> <code>trace</code>.
> * This is an insignificant overhead since evaluating a category
> * takes about 1% of the time it takes to actually log.
> *
> * @return boolean - <code>true</code> if this category is trace
> * enabled, <code>false</code> otherwise.
> */
> public boolean isTraceEnabled() {
> return(disable >= TraceablePriority.TRACE_INT) ?
> false :
>
> TraceablePriority.TRACE.isGreaterOrEqual(this.getChainedPriority());
> }
>
> // Any sub-class of Category must also have its own
> implementation of
> // CategoryFactory.
> public static class Factory implements CategoryFactory {
> public Factory() {
> }
>
> public Category makeNewCategoryInstance(String name) {
> return new TraceableCategory(name);
> }
> }
> }
>
> /**
> * This class introduces a new priority level called TRACE. TRACE has
> * lower priority than DEBUG.
> */
> public class TraceablePriority extends Priority {
> public static final int TRACE_INT = 800;
>
> // We assimilate TRACE to DEBUG on Syslog
> private static final int SYSLOG_TRACE_INT = 7;
>
> public static final TraceablePriority TRACE =
> new TraceablePriority(TRACE_INT, "TRACE", SYSLOG_TRACE_INT);
>
> protected TraceablePriority(int level, String strLevel, int
> syslogEquiv) {
> super(level, strLevel, syslogEquiv);
> }
>
> public static Priority toPriority(String sArg) {
> if (sArg == null)
> return TraceablePriority.TRACE;
>
> return (sArg.equalsIgnoreCase("TRACE")) ?
> TraceablePriority.TRACE :
> Priority.toPriority(sArg);
> }
>
> public static Priority toPriority(int i) throws
> IllegalArgumentException {
> return (i == TRACE_INT) ?
> TraceablePriority.TRACE :
> Priority.toPriority(i);
> }
> }
>
> Then you would have an entry like this in your log4j.xml file:
> <!-- Note the class attributes! -->
> <root class="TraceableCategory">
> <priority value ="trace"
> class="TraceablePriority"/>
> <appender-ref ref="MAIN" />
> </root>
>
> There's no need for mucking around with Hierarchies. The
> package scope used
> in Priority is a nuisance (I consider the use of package scope to be a
> design flaw in general), but inheratance let me treat it as
> private data and
> continue on.
>
> -Jim Moore
>
>
> -----Original Message-----
> From: Geert Mergan [mailto:[EMAIL PROTECTED]]
> Sent: Thursday, February 15, 2001 10:42 AM
> To: [EMAIL PROTECTED]
> Subject: adding custom priorities
>
>
> Hello,
>
> I suppose I'm not the only one's trying to define custom
> priorities (TRACE,
> ALWAYS, DEBUG2). It seems this is not as easy as I hoped it would be.
>
> I've started with writing MyPriority (extending Priority as
> the javadoc says
> you shoulds when enlarging the priority set). That already gave some
> problems because the _INT fields have package scope. This seems like a
> design flaw to me, since I'd like to access these fields in
> MyPriority (in
> com.mycompany.util.logging package), but I managed to bypass
> via copy/paste
> (or so I hope).
>
> Now the next thing I do is writing MyCategory (extends
> Category) since I
> need to add the methods trace(), always() and debug2(). I
> suppose I must
> also implement getInstance() because otherwise I won't be
> able to create
> MyCategory events. And then I have to write a MyHierarchy class since
> getInstance() requires a hierarchy and who knows what other
> classes I'll
> have to subclass and I won't even be sure that it will work so...
>
> I start to suspect I'm not on the right track to add custom
> priorities.
> Anyone every tried to add custom priorities?
>
> G.
> ---------------
> Geert Mergan
> Java Developer
> Email: [EMAIL PROTECTED]
> Phone: +32-2-3571765
>
> EuropeanInvestor.com
> Lasne Business Park
> Chaussée de Louvain 431, Building F
> B-1380 Lasne
> Phone: +32-2-3571711
> Fax: +32-2-3571700
> URL: http://www.europeaninvestor.com
>
>
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