dynamic configuration of file appender

[Bob Sturim]

I have a particular requirement in log4j. I want the user to be able to define virtually all aspects of a file appender (in this case a RollingFileAppender), except for the name and location of the log file. Ideally, I'd like the application to read the configuration file as normal, and then retrieve the file appender and override the filename for that appender. My configuration file looks as follows:

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">
<log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/">
 
<appender name="CONSOLE" class="org.apache.log4j.ConsoleAppender">
<param name="Threshold" value="WARN" />
<layout class="org.apache.log4j.PatternLayout">
<param name="ConversionPattern"
value="%d{ISO8601} %m%n" />
</layout>
</appender>
    <appender name="FileOutput"
             class="org.apache.log4j.RollingFileAppender"> 
        <!-- Note that the CrossTest application programmatically overrides the log file location
             so this value will be ignored -->
    <param name="File"   value="${user.home}/CrossTest.Workspace/crosstest.log" />
    <param name="Append" value="true" />
    <param name="MaxFileSize" value="1000KB" />
    <param name="MaxBackupIndex" value="3" />
<layout class="org.apache.log4j.PatternLayout">
<param name="ConversionPattern"
value="%p[%t]-%C{1}.%M(%L) %d{ISO8601} | %m%n" />
</layout>
    </appender>
<logger name="com.crosstest">
<level value="INFO" />
<appender-ref ref="FileOutput" />
</logger>
<root>
<level value="WARN" />
<appender-ref ref="CONSOLE" />
</root>
</log4j:configuration>

Now, in my main class, if look at which appenders are defined, I only see the CONSOLE appender (even though the log file is being written). The code I use to retrieve the appenders looks as follows:

 
            for (Enumeration e = LogManager.getRootLogger().getAllAppenders(); e
                    .hasMoreElements() :wink:  {
                Appender a = (Appender) e.nextElement();
            }

Any idea why I'm not able to programmatically retrieve the FileOutput appender? Is there another better/simpler way to do what I'm trying to do?

Thanks.

[Carol Enderlin]

Your fileoutput appender isn't associated with the root logger, it is associated with your other logger in your xml file. When you get all the root logger's appenders it would not be in the list.

You can get it from that other logger.