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<p><img class="editor-inline-macro" src="/plugins/servlet/confluence/placeholder/macro?definition=e3RvY30&amp;locale=en_GB&amp;version=2" data-macro-name="toc"></p><h3>Configuration</h3><p>Basic configuration of the standard JDK to show logging methods can be accomplished with the following procedure:</p><p>In file %JAVA_HOME%/jre/lib/logging.properties or equivalent</p><ul><li><p>set the log handler is configured to show all levels</p><table class="wysiwyg-macro" data-macro-name="code" style="background-image: url(/plugins/servlet/confluence/placeholder/macro-heading?definition=e2NvZGV9&amp;locale=en_GB&amp;version=2); background-repeat: no-repeat;" data-macro-body-type="PLAIN_TEXT"><tr><td class="wysiwyg-macro-body"><pre>java.util.logging.ConsoleHandler.level = ALL
</pre></td></tr></table></li><li><p>set levels for the specific logging names that you wish to log</p><table class="wysiwyg-macro" data-macro-name="code" style="background-image: url(/plugins/servlet/confluence/placeholder/macro-heading?definition=e2NvZGV9&amp;locale=en_GB&amp;version=2); background-repeat: no-repeat;" data-macro-body-type="PLAIN_TEXT"><tr><td class="wysiwyg-macro-body"><pre>com.foo.level = FINE

com.foo.MyClass.level = FINEST </pre></td></tr></table></li></ul><h3>@Log</h3><p>You can annotate your classes with the @Log transformation to automatically inject a logger in your Groovy classes, under the <code>log</code> property. Four kind of loggers are actually available:</p><ul><li><a href="http://groovy.codehaus.org/api/groovy/util/logging/Log.html"><code>@Log</code></a> for java.util.logging</li><li><code><a href="http://groovy.codehaus.org/api/groovy/util/logging/Commons.html">@Commons</a></code> for Commons-Logging</li><li><a href="http://groovy.codehaus.org/api/groovy/util/logging/Log4j.html"><code>@Log4j</code></a> for Log4J</li><li><code><a href="http://groovy.codehaus.org/api/groovy/util/logging/Slf4j.html">@Slf4j</a></code> for SLF4J</li></ul><p>Here's a sample usage of the @Log transformation:</p><table class="wysiwyg-macro" data-macro-name="code" style="background-image: url(/plugins/servlet/confluence/placeholder/macro-heading?definition=e2NvZGV9&amp;locale=en_GB&amp;version=2); background-repeat: no-repeat;" data-macro-body-type="PLAIN_TEXT"><tr><td class="wysiwyg-macro-body"><pre>import groovy.util.logging.*

@Log
class Car {
    Car() {
        log.info 'Car constructed'
    }
}

def c = new Car()
</pre></td></tr></table><p>You can change the name of the logger by specifying a different name, for instance with <code>@Log('myLoggerName')</code>.</p><p>Another particularity of these logger AST transformations is that they take care of wrapping and safe-guarding logger calls with the usual <code>isSomeLevelEnabled()</code> calls. So when you write <code>log.info 'Car constructed'</code>, the generated code is actually equivalent to:</p><table class="wysiwyg-macro" data-macro-name="code" style="background-image: url(/plugins/servlet/confluence/placeholder/macro-heading?definition=e2NvZGV9&amp;locale=en_GB&amp;version=2); background-repeat: no-repeat;" data-macro-body-type="PLAIN_TEXT"><tr><td class="wysiwyg-macro-body"><pre>if (log.isLoggable(Level.INFO)) {
    log.info 'Car constructed'
}
</pre></td></tr></table><h3>Tracing Method Calls</h3><p>In order to enable tracing of how Groovy calls MetaMethods, use the following settings:</p><p>in file %JAVA_HOME%/jre/lib/logging.properties or equivalent</p><ul><li><p>make sure your log handler is configured to show level 'FINER' at least,<br />e.g.</p><table class="wysiwyg-macro" data-macro-name="code" style="background-image: url(/plugins/servlet/confluence/placeholder/macro-heading?definition=e2NvZGV9&amp;locale=en_GB&amp;version=2); background-repeat: no-repeat;" data-macro-body-type="PLAIN_TEXT"><tr><td class="wysiwyg-macro-body"><pre>java.util.logging.ConsoleHandler.level = ALL
</pre></td></tr></table></li><li><p>set MetaClass logging to 'FINER' at least,<br />e.g.</p><table class="wysiwyg-macro" data-macro-name="code" style="background-image: url(/plugins/servlet/confluence/placeholder/macro-heading?definition=e2NvZGV9&amp;locale=en_GB&amp;version=2); background-repeat: no-repeat;" data-macro-body-type="PLAIN_TEXT"><tr><td class="wysiwyg-macro-body"><pre>groovy.lang.MetaClass.level = FINER
</pre></td></tr></table></li><li><p>set the appropriate Level for the Classes and optionally method names<br /> that you want to trace. The name for the appropriate logger starts with<br /> 'methodCalls' and optionally ends with the method name,<br />e.g.</p><table class="wysiwyg-macro" data-macro-name="code" style="background-image: url(/plugins/servlet/confluence/placeholder/macro-heading?definition=e2NvZGV9&amp;locale=en_GB&amp;version=2); background-repeat: no-repeat;" data-macro-body-type="PLAIN_TEXT"><tr><td class="wysiwyg-macro-body"><pre># trace all method calls
methodCalls.level = FINER

# trace method calls to the 'String' class
methodCalls.java.lang.String.level = FINER

# trace method calls to Object.println()
methodCalls.java.lang.Object.println.level = FINER
</pre></td></tr></table></li></ul><p>Example:<br /> with tracing enabled for all method calls a Groovy command line<br /> script appears as follows (German locale)</p><pre>$ groovy -e &quot;println 'hi'&quot;
13.09.2005 14:33:05 script_from_command_line run()
FEINER: called from MetaClass.invokeMethod
13.09.2005 14:33:05 script_from_command_line println('hi')
FEINER: called from MetaClass.invokeMethod
hi
</pre><h3>See Also</h3><ul><li><a href="http://groovy.codehaus.org/api/groovy/util/logging/package-summary.html">groovy.util.logging</a> package</li></ul>