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   <title>Example: Logging with Java&#8217;s java.util.logging via Slf4j</title><link rel="stylesheet" type="text/css" href="css/docbook.css"><meta name="generator" content="DocBook XSL Stylesheets V1.79.1"><meta name="keywords" content="jetty, servlet, servlet-api, cometd, http, websocket, eclipse, maven, java, server, software"><link rel="home" href="index.html" title="Jetty"><link rel="up" href="configuring-logging.html" title="Chapter&nbsp;11.&nbsp;Jetty Logging"><link rel="prev" href="example-logging-log4j.html" title="Example: Logging with Apache Log4j"><link rel="next" href="example-logging-java-util-logging-native.html" title="Example: Logging with Java&#8217;s java.util.logging via JavaUtilLog"><link xmlns:jfetch="java:org.eclipse.jetty.xslt.tools.JavaSourceFetchExtension" xmlns:fetch="java:org.eclipse.jetty.xslt.tools.SourceFetchExtension" xmlns:d="http://docbook.org/ns/docbook" xmlns:l="http://docbook.sourceforge.net/xmlns/l10n/1.0" xmlns:xslthl="http://xslthl.sf.net" xmlns:gcse="http://www.google.com" xmlns:date="http://exslt.org/dates-and-times" rel="shortcut icon" href="images/favicon.ico"><link rel="stylesheet" href="css/highlighter/foundation.css"><script src="js/highlight.pack.js"></script><script>
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      </p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="example-logging-java-util-logging"></a>Example: Logging with Java&#8217;s java.util.logging via Slf4j</h2></div></div></div><p>It is possible to have the Jetty Server logging configured so that <code class="literal">java.util.logging</code> controls the output of logging events produced by Jetty.</p><p>This example demonstrates how to configuring Jetty for logging to <code class="literal">java.util.logging</code> via <a class="link" href="http://slf4j.org/manual.html" target="_top">Slf4j</a> and the <a class="link" href="http://slf4j.org/manual.html#swapping" target="_top">Slf4j binding layer for java.util.logging</a>.
If you want to use the built-in native <code class="literal">JavaUtilLog</code> implementation, see #example-logging-java-util-logging-native .</p><p>A convenient replacement <code class="literal">logging</code> module has been created to bootstrap your <code class="literal">${jetty.base}</code> directory for logging with <code class="literal">java.util.logging</code>.</p><div class="screenexample"><pre class="screen">[mybase]$ mkdir modules
[mybase]$ cd modules

[modules]$ curl -O https://raw.githubusercontent.com/jetty-project/logging-modules/master/java.util.logging-slf4j/logging.mod
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100   826  100   826    0     0   2468      0 --:--:-- --:--:-- --:--:--  2473
[modules]$ cd ..

[mybase]$ java -jar /opt/jetty-dist/start.jar --add-to-start=logging
INFO: logging         initialised in ${jetty.base}/start.ini (appended)
MKDIR: ${jetty.base}/logs
DOWNLOAD: http://central.maven.org/maven2/org/slf4j/slf4j-jdk14/1.6.6/slf4j-jdk14-1.6.6.jar to lib/logging/slf4j-jdk14-1.6.6.jar
DOWNLOAD: http://central.maven.org/maven2/org/slf4j/slf4j-api/1.6.6/slf4j-api-1.6.6.jar to lib/logging/slf4j-api-1.6.6.jar
DOWNLOAD: https://raw.githubusercontent.com/jetty-project/logging-modules/master/java.util.logging-slf4j/jetty-logging.xml to etc/jetty-logging.xml
DOWNLOAD: https://raw.githubusercontent.com/jetty-project/logging-modules/master/java.util.logging-slf4j/logging.properties to resources/logging.properties
DOWNLOAD: https://raw.githubusercontent.com/jetty-project/logging-modules/master/java.util.logging-slf4j/jetty-logging.properties to resources/jetty-logging.properties
INFO: resources       initialised transitively
INFO: resources       enabled in     ${jetty.base}/start.ini

[mybase]$ java -jar /opt/jetty-dist/start.jar</pre></div><p>The replacement <code class="literal">logging.mod</code> performs a number of tasks.</p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><code class="literal">mybase</code> is a <code class="literal">${jetty.base}</code> directory</li><li class="listitem">The jetty-distribution is unpacked (and untouched) into <code class="literal">/opt/jetty-dist/</code> and becomes the <code class="literal">${jetty.home}</code> directory for this demonstration.</li><li class="listitem">The <code class="literal">curl</code> command downloads the replacement <code class="literal">logging.mod</code> and puts it into the <code class="literal">${jetty.base}/modules/</code> directory for use by <code class="literal">mybase</code> only.</li><li class="listitem"><p class="simpara">The <code class="literal">start.jar --add-to-start=logging</code> command performs a number of steps to make the logging module available to the <code class="literal">${jetty.base}</code> configuration.</p><div class="orderedlist"><ol class="orderedlist" type="a"><li class="listitem">The <code class="literal">--module=logging</code> command is added to the <code class="literal">${jetty.base}/start.ini</code> configuration.</li><li class="listitem">Required <code class="literal">${jetty.base}</code> directories are created: <code class="literal">${jetty.base}/logs</code> and <code class="literal">${jetty.base}/resources</code>.</li><li class="listitem"><p class="simpara">Required libraries are downloaded (if not present already): slf4j-api, and slf4j-jdk14.</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">The libraries are put in the <code class="literal">${jetty.base}/lib/logging/</code> directory.</li></ul></div></li><li class="listitem"><p class="simpara">Required configuration files are downloaded (if not present already): <code class="literal">jetty-logging.properties</code>, and <code class="literal">logging.properties</code>.</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">The configuration files are put in the <code class="literal">${jetty.base}/resources/</code> directory.</li></ul></div></li><li class="listitem"><p class="simpara">Required <code class="literal">java.util.logging</code> initialization commands are downloaded (if not present already): <code class="literal">jetty-logging.xml</code>.</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">The xml file is put in the <code class="literal">${jetty.base}/etc/</code> directory.</li></ul></div></li></ol></div></li></ol></div><p>At this point the Jetty <code class="literal">mybase</code> is configured so that the Jetty server itself will log using <code class="literal">java.util.logging</code>, using the <code class="literal">java.util.logging</code> configuration found in <code class="literal">mybase/resources/logging.properties</code>.</p><p>The server classpath can be verified by using the <code class="literal">start.jar --list-config</code> command.</p><p>In essence, Jetty is now configured to emit its own logging events to slf4j, and slf4j itself is using the static log binder found in <code class="literal">slf4j-jdk14.jar</code>, making all Jetty + Slf4j + <code class="literal">java.util.logging</code> events emitted by the Jetty server go to <code class="literal">java.util.logging</code> for routing (to console, file, etc&#8230;&#8203;).</p><p>If there any custom <code class="literal">java.util.logging</code> handlers to be used, put the implementation jar in the <code class="literal">${jetty.base}/lib/logging/</code> directory and reference them in the <code class="literal">${jetty.base}/resources/logging.properties</code> file.</p><div class="blockquote"><blockquote class="blockquote"><div xmlns:jfetch="java:org.eclipse.jetty.xslt.tools.JavaSourceFetchExtension" xmlns:fetch="java:org.eclipse.jetty.xslt.tools.SourceFetchExtension" xmlns:d="http://docbook.org/ns/docbook" xmlns:l="http://docbook.sourceforge.net/xmlns/l10n/1.0" xmlns:xslthl="http://xslthl.sf.net" xmlns:gcse="http://www.google.com" xmlns:date="http://exslt.org/dates-and-times" class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title"><i class="fa fa-asterisk" aria-hidden="true"></i> Note</h3><p><code class="literal">java.util.logging</code> is configured via the <code class="literal">${jetty.base}/resources/logging.properties</code> file during a valid startup of Jetty.</p></div><p>This means that if there is any startup errors that occur before <code class="literal">java.util.logging</code> is configured, they will likely be lost and/or not routed through your configuration.</p><p>Other logging frameworks are more reliable in that they always initialize and configure on first use, unlike <code class="literal">java.util.logging</code>.</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">While it is possible to configure <code class="literal">java.util.logging</code> sooner, even at JVM startup, the example demonstrated here does not show this technique.
For more information consult the official <code class="literal">java.util.logging.LogManager</code> javadoc <a class="link" href="http://docs.oracle.com/javase/7/docs/api/java/util/logging/LogManager.html" target="_top">documentation from Oracle</a>.</li></ul></div></blockquote></div></div><script type="text/javascript">
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