resourcebundle.java

来自「《移动Agent技术》一书的所有章节源代码。」· Java 代码 · 共 539 行 · 第 1/2 页

    /**
     * Get an object from a ResourceBundle.
     * @param key see class description.
     */
    public final Object getObject(String key) throws MissingResourceException {
        Object obj = handleGetObject(key);
        if (obj == null) {
            if (parent != null) {
                obj = parent.getObject(key);
            }
            if (obj == null)
                throw new MissingResourceException("Can't find resource",
                                                   this.getClass().getName(),
                                                   key);
        }
        return obj;
    }


    /**
     * Get the appropriate ResourceBundle subclass.
     * @param baseName see class description.
     */
    public static final ResourceBundle getBundle(String baseName)
        throws MissingResourceException
    {
        return getBundle(baseName, Locale.getDefault(),
	    /* must determine loader here, else we break stack invariant */
	    getLoader());
    }


    /**
     * Get the appropriate ResourceBundle subclass.
     * @param baseName see class description.
     * @param locale   see class description.
     */
    public static final ResourceBundle getBundle(String baseName,
                                                         Locale locale)
    {
	return getBundle(baseName, locale, getLoader());
    }

    /*
     * Automatic determination of the ClassLoader to be used to load
     * resources on behalf of the client.  N.B. The client is getLoader's
     * caller's caller.
     */
    private static ClassLoader getLoader() {
	Class[] stack = getClassContext();
	/* Magic number 2 identifies our caller's caller */
	Class c = stack[2];
	ClassLoader cl = (c == null) ? null : c.getClassLoader();
	return (cl == null) ? systemClassLoader : cl;
    }
    private static native Class[] getClassContext();
    private static SystemClassLoader systemClassLoader =
        new SystemClassLoader();

    /**
     * Get the appropriate ResourceBundle subclass.
     * @param baseName see class description.
     * @param locale see class description.
     */
    private static synchronized ResourceBundle
        getBundle(String baseName, Locale locale, ClassLoader loader)
        throws MissingResourceException
    {
        StringBuffer localeName
            = new StringBuffer("_").append(locale.toString());
        if (locale.toString().equals(""))
            localeName.setLength(0);

        ResourceBundle lookup = findBundle(baseName,localeName,loader,false);
        if(lookup == null) {
            localeName.setLength(0);
            localeName.append("_").append( Locale.getDefault().toString() );
            lookup = findBundle(baseName, localeName, loader, true);
            if( lookup == null ) {
                throw new MissingResourceException("can't find resource for "
                                                   + baseName + "_" + locale,
                                                   baseName + "_" + locale,"");
            }
        }

        // Setup lookup's ancestry. If we find an ancestor whose parent is null,
        // we set up the ancestor's parent as well.
        ResourceBundle child = lookup;
        while( (child != null) && (child.parent == null) ) {
            // Chop off the last component of the locale name and search for that
            // as the parent locale.  Use it to set the parent of current child.
            int lastUnderbar = localeName.toString().lastIndexOf('_');
            if( lastUnderbar != -1 ) {
                localeName.setLength(lastUnderbar);
//                debug("Searching for parent " + baseName + localeName);
                child.setParent( findBundle(baseName,localeName,loader,true) );
            }
            child = child.parent;
        }

        return lookup;
    }


    /**
     * Set the parent bundle of this bundle.  The parent bundle is
     * searched by getObject when this bundle does not contain a
     * particular resource.
     * @param parent this bundle's parent bundle.
     */
    protected void setParent( ResourceBundle parent ) {
        this.parent = parent;
    }


    /**
     * The internal routine that does the real work of finding and loading
     * the right ResourceBundle for a given name and locale.
     */
    private static ResourceBundle findBundle(String baseName,
                                             StringBuffer localeName,
                                             ClassLoader loader,
                                             boolean includeBase)
    {
        String localeStr = localeName.toString();
        String baseFileName = baseName.replace('.', '/');
        Object lookup = null;
        String searchName;
        Vector cacheCandidates = new Vector();
        int lastUnderbar;
        InputStream stream;

        searchLoop:
        while (true) {
            searchName = baseName + localeStr;
	    String cacheName =
		"["+Integer.toString(loader.hashCode())+"]" + searchName;

            // First, look in the cache.  We may either find the bundle we're
            // looking for or we may find that the bundle was not found by a
            // previous search.
            lookup = cacheList.get(cacheName);
            if( lookup == NOTFOUND ) {
//                debug("Found " + searchName + " in cache as NOTFOUND");
                localeName.setLength(0);
                break searchLoop;
            }
            if( lookup != null ) {
//                debug("Found " + searchName + " in cache");
                localeName.setLength(0);
                break searchLoop;
            }
            cacheCandidates.addElement( cacheName );

            // Next search for a class
//            debug("Searching for " + searchName );
            try {
                lookup = loader.loadClass(searchName).newInstance();
                break searchLoop;
            } catch( Exception e ){}

            // Next search for a Properties file.
            searchName = baseFileName + localeStr + ".properties";
//            debug("Searching for " + searchName );
            stream = loader.getResourceAsStream(searchName);
            if( stream != null ) {
		// make sure it is buffered
		stream = new java.io.BufferedInputStream(stream);
                try {
                    lookup = (Object)new PropertyResourceBundle( stream );
                    break searchLoop;
                } catch (Exception e) {}
            }

            //Chop off the last part of the locale name string and try again.
            lastUnderbar = localeStr.lastIndexOf('_');
            if( ((lastUnderbar==0)&&(!includeBase)) || (lastUnderbar == -1) ) {
                break;
            }
            localeStr = localeStr.substring(0,lastUnderbar);
            localeName.setLength(lastUnderbar);
        }


        if( lookup != null ) {
            // Add a positive result to the cache. The result may include
            // NOTFOUND
            for( int i=0; i<cacheCandidates.size(); i++ ) {
                cacheList.put(cacheCandidates.elementAt(i), lookup);
//                debug("Adding " + cacheCandidates.elementAt(i) + " to cache"
//                      + ((lookup == NOTFOUND)?" as NOTFOUND.":"."));
            }
        }
        else {
            // If we searched all the way to the base, then we can add
            // the NOTFOUND result to the cache.  Otherwise we can say
            // nothing.
            if( includeBase == true ) {
                for( int i=0; i<cacheCandidates.size(); i++ ) {
                    cacheList.put(cacheCandidates.elementAt(i), NOTFOUND);
//                    debug("Adding " + cacheCandidates.elementAt(i)
//                          + " to cache as NOTFOUND.");
                }
            }
        }

        if( (lookup == NOTFOUND) || (lookup == null) )
            return null;
        else
            return (ResourceBundle)lookup;
    }


    /** Get an object from a ResourceBundle.
     * <STRONG>NOTE: </STRONG>Subclasses must override.
     * @param key see class description.
     */
    protected abstract Object handleGetObject(String key)
        throws MissingResourceException;

    /**
     * Return an enumeration of the keys.
     * <STRONG>NOTE: </STRONG>Subclasses must override.
     */
    public abstract Enumeration getKeys();

    /**
     * For printf debugging.
     */
    private static boolean debugFlag = false;
    private static void debug(String str) {
        if( debugFlag ) {
            System.out.println("ResourceBundle: " + str);
        }
    }

    /**
     * The parent bundle is consulted by getObject when this bundle
     * does not contain a particular resource.
     */
    protected ResourceBundle parent = null;

    private static final Integer NOTFOUND = new Integer(-1);
    private static Hashtable cacheList = new Hashtable();
}


/**
 * The SystemClassLoader loads system classes (those in your classpath).
 * This is an attempt to unify the handling of system classes and ClassLoader
 * classes.
 */
class SystemClassLoader extends java.lang.ClassLoader {

    protected Class loadClass( String name, boolean resolve )
        throws ClassNotFoundException
    {
        return findSystemClass( name );
    }

    public InputStream getResourceAsStream(String name) {
        return ClassLoader.getSystemResourceAsStream(name);
    }

    public java.net.URL getResource(String name) {
        return ClassLoader.getSystemResource(name);
    }
}