为什么Log4j中两个Logger不按照级别拆分消息？

Question

I want to log all logger levels to a file (FATAL-> ALL) and simultaneousy show ERROR level and higher in the console. I'm using root logger to log all levels to a file and separate logger to log ERROR level to a console. My XML configuration file looks as follows:

<?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] %highlight{%level}{FATAL=bg_red, ERROR=red, WARN=yellow, INFO=blue} %logger{36} - %msg%n" disableAnsi="false"/>
        </Console>

        <File name="File" fileName="output.log" bufferedIO="true" >
            <PatternLayout
                    pattern="%d{HH:mm:ss.SSS} [%t] %highlight{%level}{FATAL=bg_red, ERROR=red, WARN=yellow, INFO=blue} %logger{36} - %msg%n"/>
        </File>
    </Appenders>

    <Loggers>
        <Root level="ALL">
            <AppenderRef ref="File"/>
        </Root>

        <Logger name="com.danielk" level="ERROR">
            <AppenderRef ref="Console"/>
        </Logger>

    </Loggers>
</Configuration>

I expected to have all levels of logging in the file and only "Error" and above level in the console but I have only "Error" levels on both (console and file):

23:19:54.422 [main] ERROR com.danielk.Example - error error error from Example 23:19:54.434 [main] ERROR com.danielk.Main - ERROR ERROR ERROR FROM MAIN

Messages themselves are correcty build because when I set both loggers (Root and additional) to "ALL" level I can see all kind of messages (not only "Error" level).

What should I do to split levels:

1. File - all levels
2. Console - Errors and above only?

Answer 1

You can use ThresholdFilter on console appender to filter out log events that have ERROR or more specific level ( https://logging.apache.org/log4j/2.x/manual/filters.html#ThresholdFilter ).

Entire configuration eg:

<?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] %highlight{%level}{FATAL=bg_red, ERROR=red, WARN=yellow, INFO=blue} %logger{36} - %msg%n"
                    disableAnsi="false"/>
            <ThresholdFilter level="ERROR" onMatch="ACCEPT" onMismatch="DENY"/>
        </Console>
        <File name="File" fileName="output.log" bufferedIO="true" append="false">
            <PatternLayout
                    pattern="%d{HH:mm:ss.SSS} [%t] %highlight{%level}{FATAL=bg_red, ERROR=red, WARN=yellow, INFO=blue} %logger{36} - %msg%n"/>
        </File>
    </Appenders>
    <Loggers>
        <Root level="debug">
            <AppenderRef ref="File"/>
            <AppenderRef ref="Console"/>
        </Root>
    </Loggers>
</Configuration>

PS When you specify:

<Logger name="com.danielk" level="ERROR">
   <AppenderRef ref="Console"/>
</Logger>

then log level is set to ERROR for all sub-packages and classes inside com.danielk (unless you configure more specific logger, say com.danielk.db.MyClass with a different level). That's why only errors appeared in the log file.