未记录 TRACE 级别的消息。 log4j 如何启用跟踪日志记录级别

Question

I'm currently working on a maven application that uses slf4j/log4j and I want to be able to output all log levels including trace to the console. I've configured as follows:

<?xml version="1.0" encoding="UTF-8" ?>
<Configuration status="ERROR">
    <Appenders>
        <Console name="Console" target="SYSTEM_OUT">
            <PatternLayout pattern="%d{yyyy-MM-dd HH:mm:ss.SSS} [%7pid] %-5p --- myapp              %-42.42c{1.} : %m%n" />
            <LevelRangeFilter maxLevel="TRACE" onMatch="ACCEPT" onMismatch="DENY"/>
        </Console>
    </Appenders>

    <Loggers>
        <Logger name="com.gpc.nar" level="ALL" additivity="false">
            <AppenderRef ref="Console"/>
        </Logger>
        <Root level="INFO">
            <!-- Console can still output logs from higher log levels. -->
            <AppenderRef ref="Console"/>
        </Root>
    </Loggers>
</Configuration>

Then I have a simple rest call that outputs each level to the console.

@RequestMapping(value = "/ping", method = RequestMethod.GET)
    public ResponseEntity<?> processPing() throws Exception {

        log.trace("trace");
        log.debug("debug");
        log.info("info");
        log.warn("warn");
        log.error("error");

        log.info("info enabled? : " + log.isInfoEnabled());
        log.info("trace enabled? : " + log.isTraceEnabled());

        return new ResponseEntity<>(HttpStatus.OK);
    }

Currently everything except trace is printed to the console. Changing the level in my custom logger to error will prevent debug and warn from being printed, but setting the level to trace or all doesn't seem to enable trace. log.isTraceEndable() always returns false and I'm not sure how to change it.

Answer 1

This behaviour might be due to missing minLevel in LevelRangeFilter .

Class LevelRangeFilter. This is a very simple filter based on level matching, which can be used to reject messages with priorities outside a certain range . The filter admits three options LevelMin, LevelMax and AcceptOnMatch. If the level of the LoggingEvent is not between Min and Max (inclusive), then Filter.