Log4J2(2.5)中的可加性

Question

根据http://logging.apache.org/log4j/2.x/manual/configuration.html的Log4J2手册，使用

...
      <Loggers>
        <Logger name="com.foo.Bar" level="trace">
          <AppenderRef ref="Console"/>
        </Logger>
        <Root level="error">
          <AppenderRef ref="Console"/>
        </Root>
      </Loggers>
...

并记录语句，如

Logger barLogger = LogManager.getLogger(Bar.class);
barLogger.info("A simple info message");

然而，我得到了两次信息，即。

“简单信息消息”

“简单信息消息”

public class MyApp {
 
    // Define a static logger variable so that it references the
    // Logger instance named "MyApp".
    private static final Logger logger = LogManager.getLogger(MyApp.class);
 
    public static void main(final String... args) {
 
        // Set up a simple configuration that logs on the console.
 
        logger.trace("Entering application.");
        Bar bar = new Bar();
        if (!bar.doIt()) {
            logger.error("Didn't do it.");
        }
        logger.trace("Exiting application.");
    }
}
 
public class Bar {
  static final Logger logger = LogManager.getLogger(Bar.class.getName());
 
  public boolean doIt() {
    logger.entry();
    logger.error("Did it again!");
    return logger.exit(false);
  }
}

<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="WARN">
  <Appenders>
    <Console name="Console" target="SYSTEM_OUT">
      <PatternLayout pattern="%d{HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n"/>
    </Console>
  </Appenders>
  <Loggers>
    <Logger name="com.foo.Bar" level="trace">
      <AppenderRef ref="Console"/>
    </Logger>
    <Root level="error">
      <AppenderRef ref="Console"/>
    </Root>
  </Loggers>
</Configuration>

17:13:01.540 [main] TRACE com.foo.Bar - entry
17:13:01.540 [main] TRACE com.foo.Bar - entry
17:13:01.540 [main] ERROR com.foo.Bar - Did it again!
17:13:01.540 [main] TRACE com.foo.Bar - exit (false)
17:13:01.540 [main] TRACE com.foo.Bar - exit (false)
17:13:01.540 [main] ERROR MyApp - Didn't do it.

00:45:49.951 [main] TRACE com.foo.Bar - entry
00:45:49.951 [main] TRACE com.foo.Bar - entry
00:45:49.951 [main] ERROR com.foo.Bar - Did it again!
00:45:49.951 [main] ERROR com.foo.Bar - Did it again!
00:45:49.951 [main] TRACE com.foo.Bar - exit with(false)
00:45:49.951 [main] TRACE com.foo.Bar - exit with(false)
00:45:49.951 [main] ERROR com.foo.MyApp - Didn't do it.

Answer 1

仅使用第一个匹配记录器的日志级别接受或拒绝日志事件。一旦它被接受，它将被传递给所有父记录器，不管它们指定了什么级别。我以为文件上写得很清楚，但也许不清楚。