package log4j;                import org.apache.log4j.LogManager;        import org.apache.log4j.Logger;        import org.apache.log4j.PropertyConfigurator;                public class Log4jG {        // private static Logger log =Logger.getLogger(Log4jG.class);         private static Logger log=LogManager.getLogger(Log4jG.class.getName());         private static Logger log1=LogManager.getLogger("myTest1");         private static Logger log2=LogManager.getLogger("myTest2");         private static Logger log3=LogManager.getLogger("myTest3");         public static void main(String[] args){                //  BasicConfigurator.configure();          PropertyConfigurator.configure("c:\\log4j.properties");          log.debug("debug message");          log.info("info message");          log.error("error message");                            log1.debug("test1  debug");          log1.info("test1  info message");          log1.error("test1  error message");                    log2.debug("test2  debug");          log2.info("test2  info message");          log2.error("test2  error message");                              log3.debug("test3  debug");          log3.info("test3  info message");          log3.error("test3  error message");                 }        }  

    log4j.rootLogger=INFO,A        log4j.appender.A=org.apache.log4j.FileAppender        log4j.appender.A.file=c:/rootlog.txt        log4j.appender.A.layout=org.apache.log4j.PatternLayout                log4j.logger.myTest1= DEBUG, test1        log4j.appender.test1=org.apache.log4j.FileAppender        log4j.appender.test1.File=c:/test1.log        log4j.appender.test1.layout=org.apache.log4j.PatternLayout        log4j.appender.test1.layout.ConversionPattern=%d %p [%c] - %m%n                　　                log4j.logger.myTest2= DEBUG, test2        log4j.appender.test2=org.apache.log4j.FileAppender        log4j.appender.test2.File=c:/test2.log        log4j.appender.test2.layout=org.apache.log4j.PatternLayout        log4j.appender.test2.layout.ConversionPattern=%d %p [%c] - %m%n                                log4j.logger.myTest3= DEBUG, R        log4j.appender.R=org.apache.log4j.RollingFileAppender                 log4j.appender.R.File= C:/rolling.log                # Control the maximum log file size                 log4j.appender.R.MaxFileSize=2KB                 # Archive log files (one backup file here)                 log4j.appender.R.MaxBackupIndex=1                 log4j.appender.R.layout=org.apache.log4j.PatternLayout                 log4j.appender.R.layout.ConversionPattern=%p %t %c - %m%n   

log4j1.2.17：http://logging.apache.org/log4j/1.2/download.html

log4j1.2.17  API：http://logging.apache.org/log4j/1.2/apidocs/