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java/org/apache/naming/StringManager.java

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+/*
+ *  Licensed to the Apache Software Foundation (ASF) under one or more
+ *  contributor license agreements.  See the NOTICE file distributed with
+ *  this work for additional information regarding copyright ownership.
+ *  The ASF licenses this file to You under the Apache License, Version 2.0
+ *  (the "License"); you may not use this file except in compliance with
+ *  the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+
+package org.apache.naming;
+
+import java.text.MessageFormat;
+import java.util.Hashtable;
+import java.util.Locale;
+import java.util.MissingResourceException;
+import java.util.ResourceBundle;
+
+/**
+ * An internationalization / localization helper class which reduces
+ * the bother of handling ResourceBundles and takes care of the
+ * common cases of message formating which otherwise require the
+ * creation of Object arrays and such.
+ *
+ * <p>The StringManager operates on a package basis. One StringManager
+ * per package can be created and accessed via the getManager method
+ * call.
+ *
+ * <p>The StringManager will look for a ResourceBundle named by
+ * the package name given plus the suffix of "LocalStrings". In
+ * practice, this means that the localized information will be contained
+ * in a LocalStrings.properties file located in the package
+ * directory of the classpath.
+ *
+ * <p>Please see the documentation for java.util.ResourceBundle for
+ * more information.
+ *
+ * @author James Duncan Davidson [duncan@eng.sun.com]
+ * @author James Todd [gonzo@eng.sun.com]
+ * @author Mel Martinez [mmartinez@g1440.com]
+ * @see java.util.ResourceBundle
+ */
+public class StringManager {
+
+    /**
+     * The ResourceBundle for this StringManager.
+     */
+    private final ResourceBundle bundle;
+    private final Locale locale;
+
+    /**
+     * Creates a new StringManager for a given package. This is a
+     * private method and all access to it is arbitrated by the
+     * static getManager method call so that only one StringManager
+     * per package will be created.
+     *
+     * @param packageName Name of package to create StringManager for.
+     */
+    private StringManager(String packageName) {
+        String bundleName = packageName + ".LocalStrings";
+        ResourceBundle tempBundle = null;
+        try {
+            tempBundle = ResourceBundle.getBundle(bundleName, Locale.getDefault());
+        } catch( MissingResourceException ex ) {
+            // Try from the current loader (that's the case for trusted apps)
+            // Should only be required if using a TC5 style classloader structure
+            // where common != shared != server
+            ClassLoader cl = Thread.currentThread().getContextClassLoader();
+            if( cl != null ) {
+                try {
+                    tempBundle = ResourceBundle.getBundle(
+                            bundleName, Locale.getDefault(), cl);
+                } catch(MissingResourceException ex2) {
+                    // Ignore
+                }
+            }
+        }
+        // Get the actual locale, which may be different from the requested one
+        if (tempBundle != null) {
+            locale = tempBundle.getLocale();
+        } else {
+            locale = null;
+        }
+        bundle = tempBundle;
+    }
+
+    /**
+        Get a string from the underlying resource bundle or return
+        null if the String is not found.
+
+        @param key to desired resource String
+        @return resource String matching <i>key</i> from underlying
+                bundle or null if not found.
+        @throws IllegalArgumentException if <i>key</i> is null.
+     */
+    public String getString(String key) {
+        if(key == null){
+            String msg = "key may not have a null value";
+
+            throw new IllegalArgumentException(msg);
+        }
+
+        String str = null;
+
+        try {
+            // Avoid NPE if bundle is null and treat it like an MRE
+            if (bundle != null) {
+                str = bundle.getString(key);
+            }
+        } catch(MissingResourceException mre) {
+            //bad: shouldn't mask an exception the following way:
+            //   str = "[cannot find message associated with key '" + key + "' due to " + mre + "]";
+            //     because it hides the fact that the String was missing
+            //     from the calling code.
+            //good: could just throw the exception (or wrap it in another)
+            //      but that would probably cause much havoc on existing
+            //      code.
+            //better: consistent with container pattern to
+            //      simply return null.  Calling code can then do
+            //      a null check.
+            str = null;
+        }
+
+        return str;
+    }
+
+    /**
+     * Get a string from the underlying resource bundle and format
+     * it with the given set of arguments.
+     *
+     * @param key  The key for the required message
+     * @param args The values to insert into the message
+     *
+     * @return The request string formatted with the provided arguments or the
+     *         key if the key was not found.
+     */
+    public String getString(final String key, final Object... args) {
+        String value = getString(key);
+        if (value == null) {
+            value = key;
+        }
+
+        MessageFormat mf = new MessageFormat(value);
+        mf.setLocale(locale);
+        return mf.format(args, new StringBuffer(), null).toString();
+    }
+
+    // --------------------------------------------------------------
+    // STATIC SUPPORT METHODS
+    // --------------------------------------------------------------
+
+    private static final Hashtable<String, StringManager> managers =
+            new Hashtable<>();
+
+    /**
+     * Get the StringManager for a particular package. If a manager for
+     * a package already exists, it will be reused, else a new
+     * StringManager will be created and returned.
+     *
+     * @param packageName The package name
+     *
+     * @return The instance associated with the given package
+     */
+    public static final synchronized StringManager getManager(String packageName) {
+        StringManager mgr = managers.get(packageName);
+        if (mgr == null) {
+            mgr = new StringManager(packageName);
+            managers.put(packageName, mgr);
+        }
+        return mgr;
+    }
+
+
+    public static final StringManager getManager(Class<?> clazz) {
+        return getManager(clazz.getPackage().getName());
+    }
+}