Java Resource Message getMessage(String messageKey)

Description

Get message from registered resource bundle.

License

Open Source License

Parameter

Parameter	Description
messageKey	message key

Return

localised message string, null if not found

Declaration

public static String getMessage(String messageKey) 

Method Source Code

//package com.java2s;
//License from project: Open Source License 

import java.text.MessageFormat;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.HashSet;

import java.util.Locale;
import java.util.Map;
import java.util.ResourceBundle;
import java.util.Set;

import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;

public class Main {
    /**//from  ww  w. ja v  a2s. c  om
     * Thread-local containing the general Locale for the current thread
     */
    private static ThreadLocal<Locale> threadLocale = new ThreadLocal<Locale>();
    /**
     * List of registered bundles
     */
    private static Set<String> resouceBundleBaseNames = new HashSet<String>();
    /**
     * Map of loaded bundles by Locale
     */
    private static Map<Locale, Set<String>> loadedResourceBundles = new HashMap<Locale, Set<String>>();
    /**
     * Map of cached messaged by Locale
     */
    private static Map<Locale, Map<String, String>> cachedMessages = new HashMap<Locale, Map<String, String>>();
    /**
     * Lock objects
     */
    private static ReadWriteLock lock = new ReentrantReadWriteLock();
    private static Lock readLock = lock.readLock();
    private static Lock writeLock = lock.writeLock();

    /**
     * Get message from registered resource bundle.
     *
     * @param messageKey    message key
     * @return              localised message string, null if not found
     */
    public static String getMessage(String messageKey) {
        return getMessage(messageKey, getLocale());
    }

    /**
     * Get a localised message string
     *
     * @param messageKey        the message key
     * @param locale            override the current locale
     * @return                  the localised message string, null if not found
     */
    public static String getMessage(String messageKey, Locale locale) {
        String message = null;
        Map<String, String> props = getLocaleProperties(locale);
        if (props != null) {
            message = props.get(messageKey);
        }
        return message;
    }

    /**
     * Get a localised message string, parameterized using standard MessageFormatter.
     *
     * @param messageKey    message key
     * @param params        format parameters
     * @return              the localised string, null if not found
     */
    public static String getMessage(String messageKey, Object... params) {
        return getMessage(messageKey, getLocale(), params);
    }

    /**
     * Get a localised message string, parameterized using standard MessageFormatter.
     *
     * @param messageKey        the message key
     * @param locale            override current locale
     * @param params            the localised message string
     * @return                  the localaised string, null if not found
     */
    public static String getMessage(String messageKey, Locale locale, Object... params) {
        String message = getMessage(messageKey, locale);
        if (message != null && params != null) {
            message = MessageFormat.format(message, params);
        }
        return message;
    }

    /**
     * Get the general local for the current thread, will revert to the default locale if none
     * specified for this thread.
     *
     * @return  the general locale
     */
    public static Locale getLocale() {
        Locale locale = threadLocale.get();
        if (locale == null) {
            // Get the default locale
            locale = Locale.getDefault();
        }
        return locale;
    }

    /**
     * Get the messages for a locale.
     * <p>
     * Will use cache where available otherwise will load into cache from bundles.
     *
     * @param locale    the locale
     * @return          message map
     */
    private static Map<String, String> getLocaleProperties(Locale locale) {
        Set<String> loadedBundles = null;
        Map<String, String> props = null;
        int loadedBundleCount = 0;
        try {
            readLock.lock();
            loadedBundles = loadedResourceBundles.get(locale);
            props = cachedMessages.get(locale);
            loadedBundleCount = resouceBundleBaseNames.size();
        } finally {
            readLock.unlock();
        }

        if (loadedBundles == null) {
            try {
                writeLock.lock();
                loadedBundles = new HashSet<String>();
                loadedResourceBundles.put(locale, loadedBundles);
            } finally {
                writeLock.unlock();
            }
        }

        if (props == null) {
            try {
                writeLock.lock();
                props = new HashMap<String, String>();
                cachedMessages.put(locale, props);
            } finally {
                writeLock.unlock();
            }
        }

        if (loadedBundles.size() != loadedBundleCount) {
            try {
                writeLock.lock();
                for (String resourceBundleBaseName : resouceBundleBaseNames) {
                    if (loadedBundles.contains(resourceBundleBaseName) == false) {
                        ResourceBundle resourcebundle = ResourceBundle.getBundle(resourceBundleBaseName, locale);
                        Enumeration<String> enumKeys = resourcebundle.getKeys();
                        while (enumKeys.hasMoreElements() == true) {
                            String key = enumKeys.nextElement();
                            props.put(key, resourcebundle.getString(key));
                        }
                        loadedBundles.add(resourceBundleBaseName);
                    }
                }
            } finally {
                writeLock.unlock();
            }
        }

        return props;
    }
}

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2. getMessage(String key)
3. getMessage(String key, Object... contents)
4. getMessage(String key, Object... values)
5. getMessage(String key, String... fill)
6. getMessage(String messageKey, Object[] params)
7. getMessage(String pkg, String name, Object[] args)
8. getMessage(String value, Object... args)
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