[logback-user] Changing appenders at runtime

[Ceki Gulcu]

Hi Richard,

It looks OK to me except that you seem to be omitting the call to attaching the 
new appender to the root logger. I suggest you add the following line after 
starting classAppender.

   logger.addAppender(clsssAppender);

That should do it. I hope this helps,

Richard Wallace wrote:
> Hello,
> 
> I'm trying to change the appender used at runtime during testing.  I'm 
> using the excellent Unitils project to do my unit testing and am unit 
> testing some Hibernate and Spring stuff.  The amount that gets logged is 
> too much to do to stdout so I want it to go to a file.  My problem is 
> that if I just do it to a single file all the logs run together and you 
> have a hard time telling where one test begins and another ends.  So I 
> want to change the file that is being logged to for each test.  I've got 
> the following bit of code that runs before each test class.
> 
>            LoggerContext lc = (LoggerContext) 
> LoggerFactory.getILoggerFactory ();
>            Logger logger = lc.getLogger (LoggerContext.ROOT_NAME);
>            m_originalAppender = (FileAppender) logger.detachAppender 
> ("FILE");
> 
>            String logFile = System.getProperty ("test.log.dir") + 
> File.separator
>                           + testClass.getName () + ".log";
> 
>            FileAppender classAppender = new FileAppender ();
>            classAppender.setContext (lc);
>            classAppender.setName ("FILE");
>            classAppender.setFile (logFile);
>            classAppender.setAppend (false);
>            classAppender.setLayout (m_originalAppender.getLayout ());
>            classAppender.setEncoding (m_originalAppender.getEncoding ());
>            classAppender.start ();
> 
> and here is the initial logback.xml configuration.
> 
> <configuration>
> 
>  <appender name="FILE" class="ch.qos.logback.core.FileAppender">
>    <File>test.log</File>
>    <Append>true</Append>
>    <Encoding>UTF-8</Encoding>
>    <BufferedIO>false</BufferedIO>
>    <ImmediateFlush>true</ImmediateFlush>
> 
>    <layout class="ch.qos.logback.classic.PatternLayout">
>      <pattern>
>        %-4relative [%thread] %-5level %logger{36} - %msg%n
>      </pattern>
>    </layout>
>  </appender>
> 
>  <root>
>    <level value="debug" />
>    <appender-ref ref="FILE" />
>  </root>
> </configuration>
> 
> Logging starts going to the test.log file successfully and then the 
> testClass log file gets created, but nothing is logged to it.  I'm sure 
> I'm missing something about correctly attaching it or having it listen 
> for logging events, but I can't figure out where.  Any hints?
> 
> Thanks,
> Rich
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-- 
Ceki Gülcü
Logback: The reliable, generic, fast and flexible logging framework for Java.
http://logback.qos.ch