StringManager.java
/*
* 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.HashMap;
import java.util.Locale;
import java.util.Map;
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 formatting 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 Map<String, StringManager> managers = new HashMap<>();
/**
* 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());
}
}