// Create log output file (in the local file system).
private static void setLoopLoggerFile(String outputDirName, int loopNumber) {
org.apache.log4j.Logger rootLogger = org.apache.log4j.Logger.getRootLogger();
String filename = String.format("%s/%d-DemoCrawlTool.log", outputDirName, loopNumber);
FileAppender appender = (FileAppender)rootLogger.getAppender("loop-logger");
if (appender == null) {
appender = new FileAppender();
appender.setName("loop-logger");
appender.setLayout(new PatternLayout("%d{yy/MM/dd HH:mm:ss} %p %c{2}:%L - %m%n"));
// We have to do this before calling addAppender, as otherwise Log4J warns us.
appender.setFile(filename);
appender.activateOptions();
rootLogger.addAppender(appender);
} else {
appender.setFile(filename);
appender.activateOptions();
}
}