container/catalina/src/share/org/apache/naming/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.Hashtable;
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]
 */

public class StringManager {

    /**
     * The ResourceBundle for this StringManager.
     */
    
    private ResourceBundle bundle;

    /**
     * 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";
	bundle = ResourceBundle.getBundle(bundleName);
    }

    /**
     * Get a string from the underlying resource bundle.
     *
     * @param key 
     */
    
    public String getString(String key) {
        if (key == null) {
            String msg = "key is null";

            throw new NullPointerException(msg);
        }

        String str = null;

        try {
	    str = bundle.getString(key);
        } catch (MissingResourceException mre) {
            str = "Cannot find message associated with key '" + key + "'";
        }

        return str;
    }

    /**
     * Get a string from the underlying resource bundle and format
     * it with the given set of arguments.
     *
     * @param key
     * @param args
     */

    public String getString(String key, Object[] args) {
	String iString = null;
        String value = getString(key);

	// this check for the runtime exception is some pre 1.1.6
	// VM's don't do an automatic toString() on the passed in
	// objects and barf out
	
	try {
            // ensure the arguments are not null so pre 1.2 VM's don't barf
            Object nonNullArgs[] = args;
            for (int i=0; i<args.length; i++) {
		if (args[i] == null) {
		    if (nonNullArgs==args) nonNullArgs=(Object[])args.clone();
		    nonNullArgs[i] = "null";
		}
	    }
 
            iString = MessageFormat.format(value, nonNullArgs);
	} catch (IllegalArgumentException iae) {
	    StringBuffer buf = new StringBuffer();
	    buf.append(value);
	    for (int i = 0; i < args.length; i++) {
		buf.append(" arg[" + i + "]=" + args[i]);
	    }
	    iString = buf.toString();
	}
	return iString;
    }

    /**
     * Get a string from the underlying resource bundle and format it
     * with the given object argument. This argument can of course be
     * a String object.
     *
     * @param key
     * @param arg
     */

    public String getString(String key, Object arg) {
	Object[] args = new Object[] {arg};
	return getString(key, args);
    }

    /**
     * Get a string from the underlying resource bundle and format it
     * with the given object arguments. These arguments can of course
     * be String objects.
     *
     * @param key
     * @param arg1
     * @param arg2
     */

    public String getString(String key, Object arg1, Object arg2) {
	Object[] args = new Object[] {arg1, arg2};
	return getString(key, args);
    }
    
    /**
     * Get a string from the underlying resource bundle and format it
     * with the given object arguments. These arguments can of course
     * be String objects.
     *
     * @param key
     * @param arg1
     * @param arg2
     * @param arg3
     */

    public String getString(String key, Object arg1, Object arg2,
			    Object arg3) {
	Object[] args = new Object[] {arg1, arg2, arg3};
	return getString(key, args);
    }
    
    /**
     * Get a string from the underlying resource bundle and format it
     * with the given object arguments. These arguments can of course
     * be String objects.
     *
     * @param key
     * @param arg1
     * @param arg2
     * @param arg3
     * @param arg4
     */

    public String getString(String key, Object arg1, Object arg2,
			    Object arg3, Object arg4) {
	Object[] args = new Object[] {arg1, arg2, arg3, arg4};
	return getString(key, args);
    }   
    // --------------------------------------------------------------
    // STATIC SUPPORT METHODS
    // --------------------------------------------------------------

    private static Hashtable 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
     */

    public synchronized static StringManager getManager(String packageName) {
	StringManager mgr = (StringManager)managers.get(packageName);
	if (mgr == null) {
	    mgr = new StringManager(packageName);
	    managers.put(packageName, mgr);
	}
	return mgr;
    }
}