1 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 2 "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 3 4 <html xmlns="http://www.w3.org/1999/xhtml"> 5 <head> 6 <meta http-equiv="content-type" content="text/html; charset=iso-8859-1" /> 7 <title>Localization</title> 8 <link rel="stylesheet" type="text/css" media="screen" href="css/site.css" /> 9 <link rel="stylesheet" type="text/css" href="css/prettify.css" /> 10 </head> 11 <body onload="prettyPrint()"> 12 13 <script type="text/javascript">prefix='';</script> 14 15 <script type="text/javascript" src="js/prettify.js"></script> 16 <script src="templates/header.js" type="text/javascript"></script> 17 <div id="left"> 18 <noscript>Please turn on Javascript to view this menu</noscript> 19 <script src="templates/left.js" type="text/javascript"></script> 20 </div> 21 22 <div id="content"> 23 24 25 <h1>Localization support</h1> 26 27 <p>A <a 28 href="http://markmail.org/thread/drcabfc6z42sijdo">discussion</a> 29 on the slf4j-dev mailing list spawned an open-source project 30 called <a href="http://cal10n.qos.ch"><b>CAL10N or Compiler 31 Assisted Localization</b></a>. As its name indicates, CAL10N 32 focuses on the issue of localization/internationalization in Java 33 applications. 34 </p> 35 36 <p>The <code>org.slf4j.cal10n</code> package which ships with 37 <em>slf4j-ext-${project.version}.jar</em> adds an extremely thin 38 layer on top of CALI0N to offer localized logging.</p> 39 40 41 <p>Once you have a handle on an <a 42 href="http://cal10n.qos.ch/apidocs/ch/qos/cal10n/IMessageConveyor.html">IMessageConveyor</a> 43 instance, you can create a <a 44 href="xref/org/slf4j/cal10n/LocLoggerFactory.html">LocLoggerFactory</a>, 45 which in turn can create <a 46 href="xref/org/slf4j/cal10n/LocLogger.html">LocLogger</a> 47 instances capable of doing localized logging. 48 </p> 49 50 51 <p>Let us assume that you have defined localized message in your 52 application. In accordance with the CAL10N's philosophy, you have 53 the declared the keys for those messages in the enum type 54 <code>Production</code>.</p> 55 56 57 <pre class="prettyprint source">import ch.qos.cal10n.LocaleData; 58 import ch.qos.cal10n.Locale; 59 import ch.qos.cal10n.BaseName; 60 61 @BaseName("production") 62 @LocaleData( { @Locale("en_UK"), @Locale("ja_JP") }) 63 public enum Production { 64 APPLICATION_STARTED, 65 APPLICATION_STOPPED, 66 ... 67 DB_CONNECTION, 68 DB_CONNECTION_FAILURE; 69 }</pre> 70 71 <p>It is assumed that you have created appropriate bundle file for 72 the various locales "en_UK" and "ja_JP" as appropriate. Here is a 73 sample bundle for the "en_UK" locale. 74 </p> 75 76 77 <pre class="source">APPLICATION_STARTED=Application <b>{0}</b> has started. 78 APPLICATION_STOPPED=Application <b>{0}</b> has stopped. 79 ... </pre> 80 81 <p>Then, you 82 can instantiate a <code>IMessageConveyor</code>, inject it into a 83 <code>LogLoggerFactory</code>, retrieve multiple 84 <code>LogLogger</code> instances by name and log away, as the next 85 sample code illustrates. 86 </p> 87 88 89 <pre class="prettyprint source">import java.util.Locale; 90 91 import org.slf4j.cal10n.LocLogger; 92 import org.slf4j.cal10n.LocLoggerFactory; 93 94 import ch.qos.cal10n.IMessageConveyor; 95 import ch.qos.cal10n.MessageConveyor; 96 97 public class MyApplication { 98 99 // create a message conveyor for a given locale 100 IMessageConveyor messageConveyor = new MessageConveyor(Locale.UK); 101 102 // create the LogLoggerFactory 103 LocLoggerFactory llFactory_uk = new LocLoggerFactory(messageConveyor); 104 105 // create a locLogger 106 LocLogger locLogger = llFactory_uk.getLocLogger(this.getClass()); 107 108 109 public void applicationStart() { 110 locLogger.info(Production.APPLICATION_STARTED, "fooApp"); 111 // .. 112 } 113 114 public void applicationStop() { 115 locLogger.info(Production.APPLICATION_STOPPED, "fooApp"); 116 // ... 117 } 118 }</pre> 119 120 <p>Assuming the resource bundle 121 <em>production_en_UK.properties</em> exists, and the underlying 122 logging framework is enabled for the info level, log messages will 123 be output in UK English. 124 </p> 125 126 <p>Note that a <code>LogLogger</code> is a regular SLF4J logger 127 with additional methods supporting localization. For those 128 additional methods which take an enum as first parameter, 129 <code>LogLogger</code> follows the standard Java convention for 130 parameter substitution as defined by the <a 131 href="http://java.sun.com/j2se/1.5.0/docs/api/java/text/MessageFormat.html">java.text.MessageFormat</a> 132 class. For non-localized logs, which take a String as first 133 parameter, <code>LogLogger</code> follows the {} convention, as 134 customary for all <code>org.slf4j.Logger</code> implementations. 135 </p> 136 137 <p>Here is an example illustrating the difference.</p> 138 139 <pre class="prettyprint source">import ...; 140 public class MyApplication { 141 142 IMessageConveyor messageConveyor = new MessageConveyor(Locale.UK); 143 LocLoggerFactory llFactory_uk = new LocLoggerFactory(messageConveyor); 144 LocLogger locLogger = llFactory_uk.getLocLogger(this.getClass()); 145 146 public void someMethod() { 147 // follows the MessageFormat convention 148 locLogger.info(Production.APPLICATION_STARTED, "fooApp"); 149 150 // follows the {} convention 151 logLogger.info("Hello {}", name); 152 ... 153 } 154 }</pre> 155 <script src="templates/footer.js" type="text/javascript"></script> 156 </div> 157 </body> 158 </html> 159
