slf4j-site/src/site/pages/localization.html - platform/external/slf4j - Git at Google

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     <h1>Localization support</h1>

     <p>A <a
     href="http://markmail.org/thread/drcabfc6z42sijdo">discussion</a>
     on the slf4j-dev mailing list spawned an open-source project
     called <a href="http://cal10n.qos.ch"><b>CAL10N or Compiler
     Assisted Localization</b></a>. As its name indicates, CAL10N
     focuses on the issue of localization/internationalization in Java
     applications.
     </p>

     <p>The <code>org.slf4j.cal10n</code> package which ships with
     <em>slf4j-ext-${project.version}.jar</em> adds an extremely thin
     layer on top of CALI0N to offer localized logging.</p>


     <p>Once you have a handle on an <a
     href="http://cal10n.qos.ch/apidocs/ch/qos/cal10n/IMessageConveyor.html">IMessageConveyor</a>
     instance, you can create a <a
     href="xref/org/slf4j/cal10n/LocLoggerFactory.html">LocLoggerFactory</a>,
     which in turn can create <a
     href="xref/org/slf4j/cal10n/LocLogger.html">LocLogger</a>
     instances capable of doing localized logging.
     </p>


     <p>Let us assume that you have defined localized message in your
     application. In accordance with the CAL10N's philosophy, you have
     the declared the keys for those messages in the enum type
     <code>Production</code>.</p>


    <pre class="prettyprint source">import ch.qos.cal10n.LocaleData;
 import ch.qos.cal10n.Locale;
 import ch.qos.cal10n.BaseName;

 @BaseName("production")
 @LocaleData( { @Locale("en_UK"), @Locale("ja_JP") })
 public enum Production  {
   APPLICATION_STARTED,
   APPLICATION_STOPPED,
   ...
   DB_CONNECTION,
   DB_CONNECTION_FAILURE;
 }</pre>

     <p>It is assumed that you have created appropriate bundle file for
     the various locales "en_UK" and "ja_JP" as appropriate. Here is a
     sample bundle for the "en_UK" locale.
     </p>


     <pre class="source">APPLICATION_STARTED=Application <b>{0}</b> has started.
 APPLICATION_STOPPED=Application <b>{0}</b> has stopped.
 ... </pre>

     <p>Then, you
     can instantiate a <code>IMessageConveyor</code>, inject it into a
     <code>LogLoggerFactory</code>, retrieve multiple
     <code>LogLogger</code> instances by name and log away, as the next
     sample code illustrates.
     </p>


     <pre class="prettyprint source">import java.util.Locale;

 import org.slf4j.cal10n.LocLogger;
 import org.slf4j.cal10n.LocLoggerFactory;

 import ch.qos.cal10n.IMessageConveyor;
 import ch.qos.cal10n.MessageConveyor;

 public class MyApplication {

   // create a message conveyor for a given locale
   IMessageConveyor  messageConveyor = new MessageConveyor(Locale.UK);

   // create the LogLoggerFactory
   LocLoggerFactory llFactory_uk = new LocLoggerFactory(messageConveyor);

   // create a locLogger
   LocLogger locLogger = llFactory_uk.getLocLogger(this.getClass());


   public void applicationStart() {
     locLogger.info(Production.APPLICATION_STARTED, "fooApp");
     // ..
   }

   public void applicationStop() {
     locLogger.info(Production.APPLICATION_STOPPED, "fooApp");
     // ...
   }
 }</pre>

     <p>Assuming the resource bundle
     <em>production_en_UK.properties</em> exists, and the underlying
     logging framework is enabled for the info level, log messages will
     be output in UK English.
     </p>

     <p>Note that a <code>LogLogger</code> is a regular SLF4J logger
     with additional methods supporting localization. For those
     additional methods which take an enum as first parameter,
     <code>LogLogger</code> follows the standard Java convention for
     parameter substitution as defined by the <a
     href="http://java.sun.com/j2se/1.5.0/docs/api/java/text/MessageFormat.html">java.text.MessageFormat</a>
     class. For non-localized logs, which take a String as first
     parameter, <code>LogLogger</code> follows the {} convention, as
     customary for all <code>org.slf4j.Logger</code> implementations.
     </p>

     <p>Here is an example illustrating the difference.</p>

     <pre  class="prettyprint source">import ...;
 public class MyApplication {

   IMessageConveyor  messageConveyor = new MessageConveyor(Locale.UK);
   LocLoggerFactory llFactory_uk = new LocLoggerFactory(messageConveyor);
   LocLogger locLogger = llFactory_uk.getLocLogger(this.getClass());

   public void someMethod() {
     // follows the MessageFormat convention
     locLogger.info(Production.APPLICATION_STARTED, "fooApp");

    // follows the {} convention
    logLogger.info("Hello {}", name);
    ...
   }
 }</pre>
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	<html xmlns="http://www.w3.org/1999/xhtml">
	<head>
	<meta http-equiv="content-type" content="text/html; charset=iso-8859-1" />
	<title>Localization</title>
	<link rel="stylesheet" type="text/css" media="screen" href="css/site.css" />
	<link rel="stylesheet" type="text/css" href="css/prettify.css" />
	</head>
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	<script src="templates/left.js" type="text/javascript"></script>
	</div>

	<div id="content">


	<h1>Localization support</h1>

	<p>A <a
	href="http://markmail.org/thread/drcabfc6z42sijdo">discussion</a>
	on the slf4j-dev mailing list spawned an open-source project
	called <a href="http://cal10n.qos.ch"><b>CAL10N or Compiler
	Assisted Localization</b></a>. As its name indicates, CAL10N
	focuses on the issue of localization/internationalization in Java
	applications.
	</p>

	<p>The <code>org.slf4j.cal10n</code> package which ships with
	<em>slf4j-ext-${project.version}.jar</em> adds an extremely thin
	layer on top of CALI0N to offer localized logging.</p>


	<p>Once you have a handle on an <a
	href="http://cal10n.qos.ch/apidocs/ch/qos/cal10n/IMessageConveyor.html">IMessageConveyor</a>
	instance, you can create a <a
	href="xref/org/slf4j/cal10n/LocLoggerFactory.html">LocLoggerFactory</a>,
	which in turn can create <a
	href="xref/org/slf4j/cal10n/LocLogger.html">LocLogger</a>
	instances capable of doing localized logging.
	</p>


	<p>Let us assume that you have defined localized message in your
	application. In accordance with the CAL10N's philosophy, you have
	the declared the keys for those messages in the enum type
	<code>Production</code>.</p>


	<pre class="prettyprint source">import ch.qos.cal10n.LocaleData;
	import ch.qos.cal10n.Locale;
	import ch.qos.cal10n.BaseName;

	@BaseName("production")
	@LocaleData( { @Locale("en_UK"), @Locale("ja_JP") })
	public enum Production {
	APPLICATION_STARTED,
	APPLICATION_STOPPED,
	...
	DB_CONNECTION,
	DB_CONNECTION_FAILURE;
	}</pre>

	<p>It is assumed that you have created appropriate bundle file for
	the various locales "en_UK" and "ja_JP" as appropriate. Here is a
	sample bundle for the "en_UK" locale.
	</p>


	<pre class="source">APPLICATION_STARTED=Application <b>{0}</b> has started.
	APPLICATION_STOPPED=Application <b>{0}</b> has stopped.
	... </pre>

	<p>Then, you
	can instantiate a <code>IMessageConveyor</code>, inject it into a
	<code>LogLoggerFactory</code>, retrieve multiple
	<code>LogLogger</code> instances by name and log away, as the next
	sample code illustrates.
	</p>


	<pre class="prettyprint source">import java.util.Locale;

	import org.slf4j.cal10n.LocLogger;
	import org.slf4j.cal10n.LocLoggerFactory;

	import ch.qos.cal10n.IMessageConveyor;
	import ch.qos.cal10n.MessageConveyor;

	public class MyApplication {

	// create a message conveyor for a given locale
	IMessageConveyor messageConveyor = new MessageConveyor(Locale.UK);

	// create the LogLoggerFactory
	LocLoggerFactory llFactory_uk = new LocLoggerFactory(messageConveyor);

	// create a locLogger
	LocLogger locLogger = llFactory_uk.getLocLogger(this.getClass());


	public void applicationStart() {
	locLogger.info(Production.APPLICATION_STARTED, "fooApp");
	// ..
	}

	public void applicationStop() {
	locLogger.info(Production.APPLICATION_STOPPED, "fooApp");
	// ...
	}
	}</pre>

	<p>Assuming the resource bundle
	<em>production_en_UK.properties</em> exists, and the underlying
	logging framework is enabled for the info level, log messages will
	be output in UK English.
	</p>

	<p>Note that a <code>LogLogger</code> is a regular SLF4J logger
	with additional methods supporting localization. For those
	additional methods which take an enum as first parameter,
	<code>LogLogger</code> follows the standard Java convention for
	parameter substitution as defined by the <a
	href="http://java.sun.com/j2se/1.5.0/docs/api/java/text/MessageFormat.html">java.text.MessageFormat</a>
	class. For non-localized logs, which take a String as first
	parameter, <code>LogLogger</code> follows the {} convention, as
	customary for all <code>org.slf4j.Logger</code> implementations.
	</p>

	<p>Here is an example illustrating the difference.</p>

	<pre class="prettyprint source">import ...;
	public class MyApplication {

	IMessageConveyor messageConveyor = new MessageConveyor(Locale.UK);
	LocLoggerFactory llFactory_uk = new LocLoggerFactory(messageConveyor);
	LocLogger locLogger = llFactory_uk.getLocLogger(this.getClass());

	public void someMethod() {
	// follows the MessageFormat convention
	locLogger.info(Production.APPLICATION_STARTED, "fooApp");

	// follows the {} convention
	logLogger.info("Hello {}", name);
	...
	}
	}</pre>
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