How can I direct log4j output so that different log levels go to different appenders?

问题

Is it possible to have "debug" and "info" output written to the console while the "info" output is only written to some log file? For example, given this logging:

LOG.debug(fileContent);
LOG.info(fileLength);

What does a corresponding log4j.xml look like?

回答1:

Ok, I've got it now:

<log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/">
    <appender name="console" class="org.apache.log4j.ConsoleAppender">
        ...
    </appender>

    <appender name="otherAppender"
              class="org.apache.log4j.FileAppender FileAppender">
       <param name="Threshold" value="INFO"/>
        ...
    </appender>

    <root>
        <priority     value="debug" />
        <appender-ref ref="console" />
        <appender-ref ref="otherAppender" />
    </root>
</log4j:configuration>

Thanks for your help!

回答2:

That is definitely possible. The configuration would look something like this (not checked for syntactic correctness):

<log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/">
    <appender name="console" class="org.apache.log4j.ConsoleAppender">
        ...
    </appender>

    <appender name="otherAppender"
              class="org.apache.log4j.FileAppender FileAppender">
        ...
    </appender>

    <logger name="com.mycompany.mypackage.MyClass">
        <level        value="info"/>
        <appender-ref ref="otherAppender" />
    </logger>

    <root>
        <priority     value="debug" />
        <appender-ref ref="console" />
    </root>
</log4j:configuration>

All debug and info messages go to the console appender. Info messages go to otherAppender.

回答3:

Go to this page for some examples.

It's as simple as adding two different appenders to your program, one appender for each type of logging you want to do.

回答4:

With the configuration from Eddie I can only get the "info" output for MyClass. But what I would like to have is that the "info" output of MyClass goes to a file AND the "debug" output of MyClass goes to console.

回答5:

Do as rwwilden suggested but remove this part:

<logger name="com.mycompany.mypackage.MyClass">
    <level value="info"/>
    <appender-ref ref="otherAppender" />
</logger>

And add <param name="Threshold" value="INFO"/> under the otherAppender.

来源：https://stackoverflow.com/questions/751431/how-can-i-direct-log4j-output-so-that-different-log-levels-go-to-different-appen

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log4j