ResourceBundle 类getObject，在里面调用了抽象方法

Question

[code="java"]
public final Object getObject(String key)。
从此资源包或它的某个父包中获取给定值的对象。此方法首先尝试使用 handleGetObject 从此资源包中获取对象。
[/code]

然后再看下handleGetObject 方法：
protected abstract Object handleGetObject(String key)

居然是抽象方法啊，怎么能使用呢？？？
小弟很是迷惑啊，求大神慷慨点拨

Answer 1

1获取ResourceBundle使用
ResourceBundle myResources =
ResourceBundle.getBundle("MyResources", currentLocale);

2、getBundle方法实现：
[code="java"]public static final ResourceBundle getBundle(String baseName)
{
return getBundleImpl(baseName, Locale.getDefault(),
/* must determine loader here, else we break stack invariant */
getLoader(),
Control.INSTANCE);
}[/code]

可以看到又调用了getBundleImpl：通过一系列调用，最终调用：
[code="java"] public ResourceBundle newBundle(String baseName, Locale locale, String format,
ClassLoader loader, boolean reload)
throws IllegalAccessException, InstantiationException, IOException {
String bundleName = toBundleName(baseName, locale);
ResourceBundle bundle = null;
if (format.equals("java.class")) {
try {
Class<? extends ResourceBundle> bundleClass
= (Class<? extends ResourceBundle>)loader.loadClass(bundleName);

        // If the class isn't a ResourceBundle subclass, throw a
        // ClassCastException.
        if (ResourceBundle.class.isAssignableFrom(bundleClass)) {
        bundle = bundleClass.newInstance();
        } else {
        throw new ClassCastException(bundleClass.getName()
                 + " cannot be cast to ResourceBundle");
        }
    } catch (ClassNotFoundException e) {
    }
    } else if (format.equals("java.properties")) {
    final String resourceName = toResourceName(bundleName, "properties");
    final ClassLoader classLoader = loader;
    final boolean reloadFlag = reload;
    InputStream stream = null;
    try {
        stream = AccessController.doPrivileged(
        new PrivilegedExceptionAction<InputStream>() {
            public InputStream run() throws IOException {
            InputStream is = null;
            if (reloadFlag) {
                URL url = classLoader.getResource(resourceName);
                if (url != null) {
                URLConnection connection = url.openConnection();
                if (connection != null) {
                    // Disable caches to get fresh data for
                    // reloading.
                    connection.setUseCaches(false);
                    is = connection.getInputStream();
                }
                }
            } else {
                is = classLoader.getResourceAsStream(resourceName);
            }
            return is;
            }
        });
    } catch (PrivilegedActionException e) {
        throw (IOException) e.getException();
    }
    if (stream != null) {
        try {
        bundle = new PropertyResourceBundle(stream);
        } finally {
        stream.close();
        }
    }
    } else {
    throw new IllegalArgumentException("unknown format: " + format);
    }
    return bundle;
}[/code]

即默认情况下最终会调用PropertyResourceBundle 进行实例化。

这是一个简单工厂 设计模式：调用getBundle时 选择实现