Download from http://logging.apache.org/log4j/index.html
Example: log4j-1.2.16.jar
Create file Main.java
import org.apache.log4j.Level;
import org.apache.log4j.Logger;
public class Main {
private static Logger logger = Logger.getLogger(Main.class);
public static void main(String[] args) {
long time = System.currentTimeMillis();
logger.info("main method called..");
logger.info("another informative message");
logger.warn("This one is a warning!");
logger.log(Level.TRACE,
"And a trace message using log() method.");
long logTime = System.currentTimeMillis() - time;
logger.debug("Time taken to log the previous messages: "
+ logTime + " msecs");
// Exception logging example:
try{
String subs = "hello".substring(6);
}catch (Exception e){
logger.error("Error in main() method:", e);
}
}
}
Create new file log4j.properties
# Log levels
log4j.rootLogger=trace, stdout, R
# Console appender configuration
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
# Pattern to output the caller's file name and line number.
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] (%F:%L) - %m%n
# Rolling File Appender
log4j.appender.R=org.apache.log4j.RollingFileAppender
# Path and file name to store the log file.
log4j.appender.R.File=./logs/applog.log
log4j.appender.R.MaxFileSize=500KB
# Keep one backup file
log4j.appender.R.MaxBackupIndex=1
# Rolling File Appender layout
log4j.appender.R.layout=org.apache.log4j.PatternLayout
log4j.appender.R.layout.ConversionPattern=%d - %c - %p - %m%n
javac -cp log4j-1.2.16.jar;. Main.java
java -cp log4j-1.2.16.jar;. Main
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| use log4j logging API |