Log4J loggers for different classes

问题:

I want to use Log4J for logging my java projects. I created a log4j.properties file in the src directory with the following content:

# Root logger option
log4j.rootLogger=INFO, file, stdout
log4j.logger.DEFAULT_LOGGER=INFO,file2

# Direct log messages to a log file
log4j.appender.file=org.apache.log4j.FileAppender
log4j.appender.file.File=file.log
log4j.appender.file.layout=org.apache.log4j.PatternLayout
log4j.appender.file.layout.ConversionPattern=%d [%t] %-5p %c - %m%n



# Direct log messages to stdout
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target=System.out
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d{ABSOLUTE} %5p %c{1}:%L - %m%n


log4j.appender.file2=org.apache.log4j.FileAppender
log4j.appender.file2.File=file2.log
log4j.appender.file2.layout=org.apache.log4j.PatternLayout
log4j.appender.file2.layout.ConversionPattern=%d [%t] %-5p %c - %m%n

For example I want to use the "DEFAULT_LOGGER" only in my main method. So I wrote:

static Logger log = Logger.getLogger("DEFAULT_LOGGER");
log.fatal("Process Logger");

But when I execute the main method I prints the message "Process Logger" to all Appenders (stdout, file and file2) But I only want to print it out to file2. How can I do that or better ro say what do I do wrong?

The second point is, when I execute the main method the second time, it does not overwrite file and file2, it justs adds a line inside the textfile. How can I avoid that?

回答1:

Log4j has something called additivity. by default it is set to true and it means that every log you write will not only be logged by the specific logger but also by its ancestors (the root logger in this case).

To set it to false try this:

log4j.additivity.DEFAULT_LOGGER = false

Learn more about it here.

回答2:

try:

log4j.additivity.DEFAULT_LOGGER = false