Programmatically find the log4j2 (beta9) log filename

Question

I am using Java 1.7 and Log4j2 (beta9) and I have the following log4j2.xml file:

<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="info">
  <Appenders>
    <Console name="CONSOLE" target="SYSTEM_OUT">
      <PatternLayout pattern="[%d{dd/MMM/yyyy HH:mm:ss.SSS}]> %-5p - %m%n"/>
    </Console>

    <RollingFile name="RollingFile" fileName="logs/foo.log" filePattern="logs/foo-%d{dd-MMM-yyyy}-%i.log">
        <Policies>
            <OnStartupTriggeringPolicy/>
        </Policies>
        <DefaultRolloverStrategy fileIndex="max" max="10"/>
        <PatternLayout pattern="[%d{dd/MMM/yyyy HH:mm:ss.SSS}]> %-5p - %m%n"/>
    </RollingFile>

    <Async name="ASYNC">
      <AppenderRef ref="RollingFile"/>
      <AppenderRef ref="CONSOLE"/>
    </Async>
  </Appenders>

  <Loggers>
    <Root level="debug">
      <AppenderRef ref="ASYNC"/>
    </Root>
  </Loggers>
</Configuration>

And as far as the logging itself goes, it does what I need.

As part of the error/exception sequence, I need to send an email with the log file as an attachment.

How do I programmatically get the 'fileName="logs/foo.log"' bit? I would really hate to have to hard code this.

Answer 1

From the Logger, iterate through all getAllAppenders looking for the one that implements RollingFileAppender, and call getFile on it. Or you could use getAppender("RollingFile") instead, if you don't mind hard-coding the appender's name.

For Log4j 1:

public static final Logger LOG = Logger.getLogger(YourClass.class);

public File getLoggerFile() {
  Appender appender = LOG.getAppender("RollingFile");
  return appender.getFile();
}

For Log4j 2: (note that this requires the non-interface logger)

public static final Logger LOG = LogManager.getLogger(YourClass.class);

public String getLoggerFileName() {
  org.apache.logging.log4j.core.Logger loggerImpl = (org.apache.logging.log4j.core.Logger) LOG;
  Appender appender = loggerImpl.getAppenders().get("RollingFile");
  // Unfortunately, File is no longer an option to return, here.
  return ((RollingFileAppender) appender).getFileName();
}

Answer 2

Paul's answer was correct with a minor modification:

public static String getLoggerFile( Logger log ) {
    org.apache.logging.log4j.core.Logger loggerImpl = (org.apache.logging.log4j.core.Logger) log;
    Appender appender = loggerImpl.getAppenders().get("RollingFile");
    return ((RollingFileAppender) appender).getFileName();
}

All credit for the answer goes to Paul!

Answer 3

Alternative method with less class casting:

        RollingFileAppender appender = (RollingFileAppender) LoggerContext.getContext().getConfiguration()
        .getAppenders().get("myRfAppenderName");
    String logFile = appender.getFileName();