Java ServiceLoader.loadInstalled方法代碼示例

import java.util.ServiceLoader; //導入方法依賴的package包/類
private void registerInstalledProviders() {
    /*
      We need to load installed providers from the
      system classpath (typically the <code>lib/ext</code>
      directory in in the Java installation directory)
      in the privileged mode in order to
      be able read corresponding jar files even if
      file read capability is restricted (like the
      applet context case).
     */
    PrivilegedAction doRegistration =
        new PrivilegedAction() {
            public Object run() {
                Iterator categories = getCategories();
                while (categories.hasNext()) {
                    Class<IIOServiceProvider> c = (Class)categories.next();
                    for (IIOServiceProvider p : ServiceLoader.loadInstalled(c)) {
                        registerServiceProvider(p);
                    }
                }
                return this;
            }
        };

    AccessController.doPrivileged(doRegistration);
}
 

import java.util.ServiceLoader; //導入方法依賴的package包/類
private void registerInstalledProviders() {
    /*
      We need to load installed providers
      in the privileged mode in order to
      be able read corresponding jar files even if
      file read capability is restricted (like the
      applet context case).
     */
    PrivilegedAction<Object> doRegistration =
        new PrivilegedAction<Object>() {
            public Object run() {
                Iterator<Class<?>> categories = getCategories();
                while (categories.hasNext()) {
                    @SuppressWarnings("unchecked")
                    Class<IIOServiceProvider> c = (Class<IIOServiceProvider>)categories.next();
                    for (IIOServiceProvider p : ServiceLoader.loadInstalled(c)) {
                        registerServiceProvider(p);
                    }
                }
                return this;
            }
        };

    AccessController.doPrivileged(doRegistration);
}
 

import java.util.ServiceLoader; //導入方法依賴的package包/類
private ServiceLoader<ScriptEngineFactory> getServiceLoader(final ClassLoader loader) {
    if (loader != null) {
        return ServiceLoader.load(ScriptEngineFactory.class, loader);
    } else {
        return ServiceLoader.loadInstalled(ScriptEngineFactory.class);
    }
}
 

import java.util.ServiceLoader; //導入方法依賴的package包/類
private static ResourceBundle loadBundleOf(String baseName,
                                           Locale targetLocale,
                                           Strategy strategy) {
    Objects.requireNonNull(baseName);
    Objects.requireNonNull(targetLocale);
    Objects.requireNonNull(strategy);

    CacheKey cacheKey = new CacheKey(baseName, targetLocale);

    ResourceBundle bundle = null;

    // Quick lookup of the cache.
    BundleReference bundleRef = cacheList.get(cacheKey);
    if (bundleRef != null) {
        bundle = bundleRef.get();
    }

    // If this bundle and all of its parents are valid,
    // then return this bundle.
    if (isValidBundle(bundle)) {
        return bundle;
    }

    // Get the providers for loading the "leaf" bundle (i.e., bundle for
    // targetLocale). If no providers are required for the bundle,
    // none of its parents will require providers.
    Class<? extends ResourceBundleProvider> type
            = strategy.getResourceBundleProviderType(baseName, targetLocale);
    if (type != null) {
        @SuppressWarnings("unchecked")
        ServiceLoader<ResourceBundleProvider> providers
            = (ServiceLoader<ResourceBundleProvider>) ServiceLoader.loadInstalled(type);
        cacheKey.setProviders(providers);
    }

    List<Locale> candidateLocales = strategy.getCandidateLocales(baseName, targetLocale);
    bundle = findBundleOf(cacheKey, strategy, baseName, candidateLocales, 0);
    if (bundle == null) {
        throwMissingResourceException(baseName, targetLocale, cacheKey.getCause());
    }
    return bundle;
}
 

import java.util.ServiceLoader; //導入方法依賴的package包/類
@Test(expectedExceptions = { NullPointerException.class })
public void testLoadNull5() {
    ServiceLoader.loadInstalled(null);
}
 

import java.util.ServiceLoader; //導入方法依賴的package包/類
/**
 * Creates a connector from a provider loaded from the ServiceLoader.
 * <p>
 * The pair (P,C) will be either one of: <br>
 * a. (JMXConnectorProvider, JMXConnector) or <br>
 * b. (JMXConnectorServerProvider, JMXConnectorServer)
 *
 * @param providerClass The service type for which an implementation
 *        should be looked up from the {@code ServiceLoader}. This will
 *        be either {@code JMXConnectorProvider.class} or
 *        {@code JMXConnectorServerProvider.class}
 *
 * @param loader The ClassLoader to use when looking up an implementation
 *        of the service. If null, then only installed services will be
 *        considered.
 *
 * @param url The JMXServiceURL of the connector for which a provider is
 *        requested.
 *
 * @param filter A filter used to exclude or return provider
 *        implementations. Typically the filter will either exclude
 *        system services (system default implementations) or only
 *        retain those.
 *        This can allow to first look for custom implementations (e.g.
 *        deployed on the CLASSPATH with META-INF/services) and
 *        then only default to system implementations.
 *
 * @param factory A functional factory that can attempt to create an
 *        instance of connector {@code C} from a provider {@code P}.
 *        Typically, this is a simple wrapper over {@code
 *        JMXConnectorProvider::newJMXConnector} or {@code
 *        JMXConnectorProviderServer::newJMXConnectorServer}.
 *
 * @throws IOException if {@code C} could not be instantiated, and
 *         at least one provider {@code P} threw an exception that wasn't a
 *         {@code MalformedURLException} or a {@code JMProviderException}.
 *
 * @throws JMXProviderException if a provider {@code P} for the protocol in
 *         <code>url</code> was found, but couldn't create the connector
 *         {@code C} for some reason.
 *
 * @return an instance of {@code C} if a provider {@code P} was found from
 *         which one could be instantiated, {@code null} otherwise.
 */
static <P,C> C getConnectorAsService(Class<P> providerClass,
                                     ClassLoader loader,
                                     JMXServiceURL url,
                                     Predicate<Provider<?>> filter,
                                     ConnectorFactory<P,C> factory)
    throws IOException {

    // sanity check
    if (JMXConnectorProvider.class != providerClass
        && JMXConnectorServerProvider.class != providerClass) {
        // should never happen
        throw new InternalError("Unsupported service interface: "
                                + providerClass.getName());
    }

    ServiceLoader<P> serviceLoader = loader == null
            ? ServiceLoader.loadInstalled(providerClass)
            : ServiceLoader.load(providerClass, loader);
    Stream<Provider<P>> stream = serviceLoader.stream().filter(filter);
    ProviderFinder<P,C> finder = new ProviderFinder<>(factory, url);

    try {
        stream.filter(finder).findFirst();
        return finder.get();
    } catch (UncheckedIOException e) {
        if (e.getCause() instanceof JMXProviderException) {
            throw (JMXProviderException) e.getCause();
        } else {
            throw e;
        }
    }
}
 

import java.util.ServiceLoader; //導入方法依賴的package包/類
void run() { ServiceLoader.loadInstalled(null); }