I read the question as "how do I define parameters once" in an XML
configuration file and the use of system properties was just a convenient way
of doing that in property file configurations. The property file example
included setting log4j.logdir in the file and I'm not aware of any capability
in XML configuration files to set system properties. If the property was
already set externally, then you could use the same type of expressions as in
the example.
On Feb 21, 2011, at 8:05 PM, Jacob Kjome wrote:
>
> Curt,
>
> Maybe I'm missing something, but how does using XML entity refs do anything
> for
> referencing Java system properties? The simple answer is that Log4j XML
> config
> files support exactly the same syntax as properties files, e.g.,....
>
> <param name="File" value="${log4j.logdir}/MyAppender1.log"/>
>
> I don't recall whether/where it's specifically documented or not, but it
> works.
>
>
> Jake
>
> On 2/20/2011 10:30 PM, Curt Arnold wrote:
>> XML entity references can be used for that purpose and are defined in the
>> XML Recommendation (http://www.w3.org/TR/xml/#sec-references).
>>
>> <!DOCTYPE log4j:configuration
>> [
>> <!ENTITY logdir "c:/data/logfiles">
>> ]>
>> <log4j:configuration>
>> ...
>> <param name="file" value="&logdir;"/>
>> ...
>> </log4j:configuration>
>>
>> On Feb 20, 2011, at 6:35 AM, Thomas Wiedmann wrote:
>>
>>> Hello,
>>>
>>> usually in flat plain text log4j.config files global system properties can
>>> be defined, which may be referenced in the configuration of different
>>> appenders, e. g.
>>>
>>> log4j.logdir=C:/Data/logfiles
>>> ...
>>> log4j.appender.MyAppender1.File=${log4j.logdir}/MyAppender1.log
>>> ...
>>> log4j.appender.MyAppender2.File=${log4j.logdir}/MyAppender2.log
>>>
>>> I found this is a very convenient way to define (and to administer) such
>>> parameters only once globally for the entire log configuration and to use
>>> it on several references as here in the appenders configuration.
>>>
>>> How can such global system properties be defined in xml-based configuration
>>> files (log4j.xml)?
>>> Where is it documented? I'd found no hint about it.
>>>
>>> Thomas Wiedmann
>>>
>>>
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>>
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