I18NProvider eingefügt

src/main/java/edu/kit/typicalc/view/TypicalcI18NProvider.java

@@ -0,0 +1,51 @@
+package edu.kit.typicalc.view;
+
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+import java.util.Locale;
+import java.util.MissingResourceException;
+import java.util.ResourceBundle;
+import org.apache.commons.lang3.StringUtils;
+import org.springframework.stereotype.Component;
+import com.vaadin.flow.i18n.I18NProvider;
+
+@Component
+/**
+ * Provides a simple implementation of the I18NProvider. 
+ * Allows for multiple languages and retrieving static Strings from .property-files.
+ */
+public class TypicalcI18NProvider implements I18NProvider {
+    
+    private static final long serialVersionUID = 8261479587838699070L;
+    
+    /**
+     * Prefix of all .property-files
+     */
+    public static final String BUNDLE_PREFIX = "language.translation";
+
+    @Override
+    public List<Locale> getProvidedLocales() {
+        return Collections.unmodifiableList(Arrays.asList(Locale.GERMAN, Locale.ENGLISH));
+    }
+
+    @Override
+    public String getTranslation(String key, Locale locale, Object... params) {
+        if(key == null) {
+            return StringUtils.EMPTY;
+        }
+        
+        String translation;
+        
+        try {
+            final ResourceBundle bundle = ResourceBundle.getBundle(BUNDLE_PREFIX, locale);
+            translation = bundle.getString(key);
+        } catch (final MissingResourceException exception) {
+            throw new IllegalStateException("this should never happen:"
+                    + " either an invalid locale is set or an invalid key is provided.");
+        }
+        
+        return translation;
+    }
+
+}