How to use dynamic file name in Log4j.xml? - log4j

Question

how to read property from properties file and use in log4j.xml if not found then use default path.
For an instance
<appender name="FILE" class="org.apache.log4j.FileAppender">
<param name="File" value="logs/${logfilename}.log" />
<layout class="org.apache.log4j.PatternLayout">
<param name="ConversionPattern" value="%d::[%t]::%-5p::%c::%x - %m%n" />
</layout>
</appender>
In above code snippet, I want to retrieve value of logfilename from properties file.If I mentioned logfilename=abc_log in property file then abc_log.log should be generated inside logs folder. If I am unable to find logfilename properties then by default location should be called for an instance /logs/default.log
could you please help in this, How I can achieve the above approach?

Answer 1

Below is a code for using Log4J for dynamically generate filename. It changes its name according to input file name and current date-time. (So helpful in case you run same file multiple times.) (Found this in another thread)
public class LogClass {
private static Logger log = Logger.getLogger(LogClass.class);
private static boolean initializationFlag = false;
private static String fileName;
private static void intializeLogger(){
log.setLevel(Level.DEBUG);
DateFormat dateFormat = new SimpleDateFormat("dd/MM/yyyy HH:mm:ss");
Date date = new Date();
RollingFileAppender appender = new RollingFileAppender();
appender.setAppend(true);
appender.setMaxFileSize("1MB");
appender.setMaxBackupIndex(1);
appender.setFile(fileName + "_" + dateFormat.format(date) + ".log");
PatternLayout layOut = new PatternLayout();
layOut.setConversionPattern("%d{yyyy-MM-dd HH:mm:ss} %-5p %c{1}:%L - %m%n");
appender.setLayout(layOut);
log.addAppender(appender);
}
public static Logger getLogger(){
if(initializationFlag == false){
intializeLogger();
initializationFlag = true;
return LogClass.log;
}
else{
return LogClass.log;
}
}
public static void setFileName(String fileName){
LogClass.fileName = fileName;
}