tgkprog tgkprog - 4 months ago 9
Java Question

log4j : detect if no config file given and programmatically set it up

Know how to set log4j to print debug and how to pro grammatically construct a default Properties object.

Want help with code to detect if log4j did not find a config file in classpath.

This for the times when don't have a log4j.xml to at least see all logs in console.

Code I have:

private static void log4Default() {
boolean noLog = true;
//how to set this to false if log4j did find a config file
// File log4f = new File("log4j.xml");
// File log4f2 = new File("log4j.properties");
//
// if(log4f.exists() || log4f2.exists()) {
// noLog = false;
// }else {
// log4f = new File("target/classes/log4j.xml");
// log4f2 = new File("target/classes/log4j.properties");
// if(log4f.exists() || log4f2.exists()) {
// noLog = false;
// }
// }
// if(noLog) {
// log4f = new File("target/test-classes/log4j.xml");
// log4f2 = new File("target/test-classes/log4j.properties");
// if(log4f.exists() || log4f2.exists()) {
// noLog = false;
// }
// }

if(noLog) {
System.out.println("no log4j config, using default");
Layout layout = new PatternLayout(" %-5p %t %d [%t][%F:%L] : %m%n");
Appender ap = new ConsoleAppender(layout , ConsoleAppender.SYSTEM_OUT);
Logger.getRootLogger().setLevel(Level.ALL);
//Logger.getRootLogger().addAppender(new ConsoleAppender(layout, ConsoleAppender.SYSTEM_ERR));
Logger.getRootLogger().addAppender(ap);
}

}


Commented out the file exists as there could be an over ride and above is not foul proof.

Answer

You can use this to check whether there is any log4j.xml/.properties file present in the classpath:

public void checkForLog4jConfigFile() {

org.apache.log4j.Logger rootLogger = org.apache.log4j.Logger.getRootLogger();
Enumeration appenders = rootLogger.getAllAppenders();
if (!appenders.hasMoreElements()) {
    System.out.println("LOG4J config file is missing");
} else {
    System.out.println("appender found "
    + ((Appender) appenders.nextElement()).getName());
}
}
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