Create Language plugin to provide languages of web site

Author: rainboyan

app/plugins/grace/demos/LanguageGrailsPlugin.groovy

@@ -0,0 +1,24 @@
+package grace.demos
+
+import grails.plugins.*
+
+class LanguageGrailsPlugin extends DynamicPlugin {
+
+    def grailsVersion = "2023.0.0 > *"
+    def version = "1.0.0"
+    def providedModules = [LanguageModuleDescriptor]
+
+    Closure doWithSpring() { {->
+            // You can also use Spring AutoConfiguration
+            languageManager(DefaultLanguageManager)
+        }
+    }
+
+    Closure doWithDynamicModules() { { ->
+        // Supported Languages
+        language(key: 'en_US', title: 'English', i18nNameKey: 'languages.en_US')
+        language(key: 'zh_CN', title: 'Chinese (Simplified Chinese)', i18nNameKey: 'languages.zh_CN')
+        language(key: 'zh_TW', title: 'Chinese (Traditional Chinese)', i18nNameKey: 'languages.zh_TW', enabled: true)
+    }}
+
+}

app/views/layouts/main.gsp

@@ -48,7 +48,7 @@
                 <li class="nav-item dropdown">
                     <a href="#" class="nav-link dropdown-toggle" data-bs-toggle="dropdown" role="button" aria-haspopup="true" aria-expanded="false">Languages</a>
                     <ul class="dropdown-menu dropdown-menu-end">
-                        <g:each var="lang" in="${['en', 'cs', 'da', 'de', 'es', 'fr', 'it', 'ja', 'nb', 'nl', 'pl', 'pt_BR', 'pt_PT', 'ru', 'sk', 'sv', 'th', 'zh_CN', 'zh_TW']}">
+                        <g:each var="lang" in="${applicationContext.getBean('languageManager').languages*.key}">
                             <g:set var="locale" value="${Locale.forLanguageTag(lang.replace('_', '-'))}"/>
                             <g:set var="paramsWithLang" value="${params + [lang:lang]}"/>
                             <li>

src/main/groovy/grace/demos/DefaultLanguageManager.groovy

@@ -0,0 +1,27 @@
+package grace.demos
+
+import grails.plugins.GrailsPluginManager
+import grails.plugins.PluginManagerAware
+
+class DefaultLanguageManager implements LanguageManager, PluginManagerAware {
+
+    private GrailsPluginManager pluginManager
+
+    DefaultLanguageManager() {
+    }
+
+    DefaultLanguageManager(GrailsPluginManager pluginManager) {
+        this.pluginManager = pluginManager
+    }
+
+    @Override
+    List<LanguageModuleDescriptor> getLanguages() {
+        this.pluginManager.getEnabledModuleDescriptorsByClass(LanguageModuleDescriptor)
+    }
+
+    @Override
+    void setPluginManager(GrailsPluginManager pluginManager) {
+        this.pluginManager = pluginManager
+    }
+
+}

src/main/groovy/grace/demos/LanguageManager.java

@@ -0,0 +1,9 @@
+package grace.demos;
+
+import java.util.List;
+
+public interface LanguageManager {
+
+    List<LanguageModuleDescriptor> getLanguages();
+
+}

src/main/groovy/grace/demos/LanguageModuleDescriptor.groovy

@@ -0,0 +1,21 @@
+package grace.demos
+
+import grails.plugins.GrailsPlugin
+import grails.plugins.descriptors.AbstractModuleDescriptor
+import grails.plugins.exceptions.PluginException
+
+class LanguageModuleDescriptor extends AbstractModuleDescriptor {
+
+    String title
+
+    LanguageModuleDescriptor() {
+        super()
+    }
+
+    @Override
+    void init(GrailsPlugin plugin, Map args) throws PluginException {
+        super.init(plugin, args)
+        this.title = args.title
+    }
+
+}