* Router Console translation infrastructure:

- Persistent lang setting with routerconsole.lang=xx
      - Loading any page with ?lang=xx changes the persistent setting
      - Add a custom Jetty handler to load foo_xx.jsp if it
        exists for language xx. This is for jsp files with lots
        of text in them. Otherwise use inline translate methods.
        Not for included jsps.
      - Add a script to create and update messages_xx.po translation
        files, and create ResourceBundles from them
      - Add class to translate strings from cached ResourceBundles
      - Add translate wrappers to HelperBase, FormHandler, and *Renderer,
        so calls can be made from both jsp and java files
      - Add two example translations on configupdate.jsp - one in
        the jsp itself and one in the helper.
      - This is for strings in routerconsole only. Will be expanded
        to other webapps and the router later.

apps/routerconsole/java/src/net/i2p/router/web/Messages.java

@@ -0,0 +1,78 @@
+package net.i2p.router.web;
+
+import java.util.Locale;
+import java.util.Map;
+import java.util.MissingResourceException;
+import java.util.ResourceBundle;
+import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+
+import net.i2p.I2PAppContext;
+import net.i2p.util.ConcurrentHashSet;
+
+/**
+ * Translate strings efficiently.
+ * We don't include an English or default ResourceBundle, we simply check
+ * for "en" and return the original string.
+ * Support real-time language changing with the routerconsole.lang property.
+ *
+ * @author zzz, from a base generated by eclipse.
+ */
+public class Messages {
+    public static final String PROP_LANG = "routerconsole.lang";
+    private static final String BUNDLE_NAME = "net.i2p.router.web.messages";
+    private static final String _localeLang = Locale.getDefault().getLanguage();
+    private static final Map<String, ResourceBundle> _bundles = new ConcurrentHashMap(2);
+    private static final Set<String> _missing = new ConcurrentHashSet(2);
+
+    /** current locale **/
+    public static String getString(String key) {
+        if (_localeLang.equals("en"))
+            return key;
+        ResourceBundle bundle = findBundle(_localeLang);
+        if (bundle == null)
+            return key;
+        try {
+            return bundle.getString(key);
+        } catch (MissingResourceException e) {
+            return key;
+        }
+    }
+
+    /** lang in routerconsole.lang property, else current locale */
+    public static String getString(String key, I2PAppContext ctx) {
+        String lang = getLanguage(ctx);
+        if (lang.equals("en"))
+            return key;
+        ResourceBundle bundle = findBundle(lang);
+        if (bundle == null)
+            return key;
+        try {
+            return bundle.getString(key);
+        } catch (MissingResourceException e) {
+            return key;
+        }
+    }
+
+    private static String getLanguage(I2PAppContext ctx) {
+        String lang = ctx.getProperty(PROP_LANG);
+        if (lang == null || lang.length() <= 0)
+            lang = _localeLang;
+        return lang;
+    }
+
+    /** cache both found and not found for speed */
+    private static ResourceBundle findBundle(String lang) {
+        ResourceBundle rv = _bundles.get(lang);
+        if (rv == null && !_missing.contains(lang)) {
+            try {
+                // Would it be faster to specify a class loader?
+                // No matter we only do this once per lang.
+                rv = ResourceBundle.getBundle(BUNDLE_NAME, new Locale(lang));
+            } catch (MissingResourceException e) {
+                _missing.add(lang);
+            }
+        }
+        return rv;
+    }
+}