Java Service类代码示例

import sun.misc.Service; //导入依赖的package包/类
public Object run() {
	Iterator itr
   		    = Service.providers(NameServiceDescriptor.class);
	while (itr.hasNext()) {
   		    NameServiceDescriptor nsd 
		= (NameServiceDescriptor)itr.next();
   		    if (providerName.
	        equalsIgnoreCase(nsd.getType()+","
       		    +nsd.getProviderName())) {
		try {
    	    	    nameService = nsd.createNameService();
    	    	    break;
		} catch (Exception e) {
		    e.printStackTrace();
    	    	    System.err.println(
			"Cannot create name service:"
		         +providerName+": " + e);
		}
   		    }
	} /* while */
        return null;
}
 

import sun.misc.Service; //导入依赖的package包/类
private static boolean loadProviderAsService() {
Iterator i = Service.providers(SelectorProvider.class,
			       ClassLoader.getSystemClassLoader());
for (;;) {
    try {
	if (!i.hasNext())
	    return false;
	provider = (SelectorProvider)i.next();
	return true;
    } catch (ServiceConfigurationError sce) {
	if (sce.getCause() instanceof SecurityException) {
	    // Ignore the security exception, try the next provider
	    continue;
	}
	throw sce;
    }
}
   }
 

import sun.misc.Service; //导入依赖的package包/类
public static void webstartSetup() {
    logger.warning("Running from Java Web Start. Performing setup.");

    // setup a URL stream handler for the Wonderland protocols.  This
    // works around the fact that URL will only find handlers
    // loaded in the system classloader, and in webstart the
    // handlers we need (wonderland.protocol.*) are in the jnlp classloader.
    //
    //
    // Note if we return null here, it will go on to try the normal
    // mechanisms defined in URL
    URL.setURLStreamHandlerFactory(new WonderlandURLStreamHandlerFactory());
    
    // set our own security manager
    logger.info("Setting security manager");
    System.setSecurityManager(new JnlpSecurityManager());
    
    // discover listeners using service loader mechanism
    Iterator<WebstartStartupListener> it = 
            Service.providers(WebstartStartupListener.class);
    while (it.hasNext()) {
        WebstartStartupListener wsl = it.next();
        wsl.onStartup();
    }
}
 

import sun.misc.Service; //导入依赖的package包/类
public NameService run() {
    Iterator itr = Service.providers(NameServiceDescriptor.class);
    while (itr.hasNext()) {
        NameServiceDescriptor nsd
            = (NameServiceDescriptor)itr.next();
        if (providerName.
            equalsIgnoreCase(nsd.getType()+","
                +nsd.getProviderName())) {
            try {
                return nsd.createNameService();
            } catch (Exception e) {
                e.printStackTrace();
                System.err.println(
                    "Cannot create name service:"
                     +providerName+": " + e);
            }
        }
    }

    return null;
}
 

import sun.misc.Service; //导入依赖的package包/类
private static boolean loadProviderAsService() {
    Iterator i = Service.providers(HttpServerProvider.class,
                                   ClassLoader.getSystemClassLoader());
    for (;;) {
        try {
            if (!i.hasNext())
                return false;
            provider = (HttpServerProvider)i.next();
            return true;
        } catch (ServiceConfigurationError sce) {
            if (sce.getCause() instanceof SecurityException) {
                // Ignore the security exception, try the next provider
                continue;
            }
            throw sce;
        }
    }
}
 

import sun.misc.Service; //导入依赖的package包/类
public static void main() {
    // in jdk.unsupported
    Class<?> caller = Reflection.getCallerClass(2);

    // removed
    JPEGCodec r = new JPEGCodec();

    // removed
    SoftCache s = new SoftCache();

    // removed
    Service.providers(S.class);
}
 

import sun.misc.Service; //导入依赖的package包/类
public Object run() {

	// uncomment the followin line before mustang integration 	
        // Service s = Service.lookup(java.sql.Driver.class);
	// ps = s.iterator();

	ps = Service.providers(java.sql.Driver.class);

	/* Load these drivers, so that they can be instantiated. 
	 * It may be the case that the driver class may not be there
         * i.e. there may be a packaged driver with the service class
         * as implementation of java.sql.Driver but the actual class
         * may be missing. In that case a sun.misc.ServiceConfigurationError
         * will be thrown at runtime by the VM trying to locate 
	 * and load the service.
         * 
	 * Adding a try catch block to catch those runtime errors
         * if driver not available in classpath but it's 
	 * packaged as service and that service is there in classpath.
	 */
		
	try {
           while (ps.hasNext()) {
               ps.next();
           } // end while
	} catch(Throwable t) {
	    // Do nothing
	}
        return null;
    }
 

import sun.misc.Service; //导入依赖的package包/类
private static PreferencesFactory factory1() {
// 2. Try service provider interface
Iterator i = Service.providers(PreferencesFactory.class,
			       ClassLoader.getSystemClassLoader());
// choose first provider instance
while (i.hasNext()) {
    try {
	return (PreferencesFactory) i.next();
    } catch (ServiceConfigurationError sce) {
	if (sce.getCause() instanceof SecurityException) {
	    // Ignore the security exception, try the next provider
	    continue;
	}
	throw sce;
    }
}

// 3. Use platform-specific system-wide default
String platformFactory =
    System.getProperty("os.name").startsWith("Windows")
    ? "java.util.prefs.WindowsPreferencesFactory"
    : "java.util.prefs.FileSystemPreferencesFactory";
try {
    return (PreferencesFactory)
	Class.forName(platformFactory, false, null).newInstance();
} catch (Exception e) {
    InternalError error = new InternalError(
	"Can't instantiate platform default Preferences factory "
	+ platformFactory);
    error.initCause(e);
    throw error;
}
   }
 

import sun.misc.Service; //导入依赖的package包/类
/**
 * Find and return all the classes that implement the ModuleDeployerSPI
 * inteface
 * 
 * @return
 */
private Class[] getClasses() {
    Iterator<ModuleDeployerSPI> it = Service.providers(ModuleDeployerSPI.class);
    
    // use a linked hash set to preserve a static ordering
    Collection<Class> names = new LinkedHashSet<Class>();
    while (it.hasNext() == true) {
        names.add(it.next().getClass());
    }

    return names.toArray(new Class[]{} );
}
 

import sun.misc.Service; //导入依赖的package包/类
/**
 * Get instances of all classes that implement the given interface,
 * defined either by service provider or by annoation.
 * @param annot the annotation to search for
 * @param clazz the class of the return type
 * @return an iterator of instantiated instances of the given type
 */
public <T> Iterator<T> getAll(Class<? extends Annotation> annot,
                              Class<T> clazz)
{
    // get the iterator for service providers
    final Iterator<T> providers = Service.providers(clazz, this);

    // get the iterator for annotations
    final Iterator<T> annots = getInstances(annot, clazz);

    // return a combined iterator
    return new Iterator<T>() {
        private boolean p = true;

        public boolean hasNext() {
            if (p && providers.hasNext()) {
                return true;
            } else {
                p = false;
                return annots.hasNext();
            }
        }

        public T next() {
            if (p) {
                return providers.next();
            } else {
                return annots.next();
            }
        }

        public void remove() {
            throw new UnsupportedOperationException("Not supported.");
        }
    };
}
 

import sun.misc.Service; //导入依赖的package包/类
static List getProviders(final Class providerClass) {
    List p = new ArrayList();
    // Service.providers(Class) just creates "lazy" iterator instance,
    // so it doesn't require do be called from privileged section
    final Iterator ps = Service.providers(providerClass);

    // the iterator's hasNext() method looks through classpath for
    // the provider class names, so it requires read permissions
    PrivilegedAction<Boolean> hasNextAction = new PrivilegedAction<Boolean>() {
        public Boolean run() {
            return ps.hasNext();
        }
    };

    while (AccessController.doPrivileged(hasNextAction)) {
        try {
            // the iterator's next() method creates instances of the
            // providers and it should be called in the current security
            // context
            Object provider = ps.next();
            if (providerClass.isInstance(provider)) {
                // $$mp 2003-08-22
                // Always adding at the beginning reverses the
                // order of the providers. So we no longer have
                // to do this in AudioSystem and MidiSystem.
                p.add(0, provider);
            }
        } catch (Throwable t) {
            //$$fb 2002-11-07: do not fail on SPI not found
            if (Printer.err) t.printStackTrace();
        }
    }
    return p;
}
 

import sun.misc.Service; //导入依赖的package包/类
static synchronized List getProviders(final Class providerClass) {
    List p = new ArrayList();
    // Service.providers(Class) just creates "lazy" iterator instance,
    // so it doesn't require do be called from privileged section
    final Iterator ps = Service.providers(providerClass);

    // the iterator's hasNext() method looks through classpath for
    // the provider class names, so it requires read permissions
    PrivilegedAction<Boolean> hasNextAction = new PrivilegedAction<Boolean>() {
        public Boolean run() {
            return ps.hasNext();
        }
    };

    while (AccessController.doPrivileged(hasNextAction)) {
        try {
            // the iterator's next() method creates instances of the
            // providers and it should be called in the current security
            // context
            Object provider = ps.next();
            if (providerClass.isInstance(provider)) {
                // $$mp 2003-08-22
                // Always adding at the beginning reverses the
                // order of the providers. So we no longer have
                // to do this in AudioSystem and MidiSystem.
                p.add(0, provider);
            }
        } catch (Throwable t) {
            //$$fb 2002-11-07: do not fail on SPI not found
            if (Printer.err) t.printStackTrace();
        }
    }
    return p;
}
 

import sun.misc.Service; //导入依赖的package包/类
@Test
public void check_federated_provider_service_is_published() {
  final Iterator providers = Service.providers(IntegralIntermediateFederatedProvider.class);

  boolean ok = providers.hasNext();
  assertThat(ok).isTrue();

  Object svc = providers.next();

  assertThat(svc).isInstanceOf(IntegralIntermediateFederatedProvider.class);
  assertThat(svc).isInstanceOf(JdbcIntermediateFederatedProvider.class);
}
 

import sun.misc.Service; //导入依赖的package包/类
@Test
public void check_unknown_database_provider_service_is_published() {
  final Iterator providers = Service.providers(IntegralIntermediateRdbmsProvider.class);

  boolean ok = providers.hasNext();
  assertThat(ok).isTrue();

  Object svc = providers.next();

  assertThat(svc).isInstanceOf(IntegralIntermediateRdbmsProvider.class);
  assertThat(svc).isInstanceOf(JdbcIntermediateRdbmsProvider.class);
}
 

import sun.misc.Service; //导入依赖的package包/类
private static Iterator providers() {
return new Iterator() {

	Class c = java.nio.charset.spi.CharsetProvider.class;
	ClassLoader cl = ClassLoader.getSystemClassLoader();
	Iterator i = Service.providers(c, cl);
	Object next = null;

	private boolean getNext() {
	    while (next == null) {
		try {
		    if (!i.hasNext())
			return false;
		    next = i.next();
		} catch (ServiceConfigurationError sce) {
		    if (sce.getCause() instanceof SecurityException) {
			// Ignore security exceptions
			continue;
		    }
		    throw sce;
		}
	    }
	    return true;
	}

	public boolean hasNext() {
	    return getNext();
	}

	public Object next() {
	    if (!getNext())
		throw new NoSuchElementException();
	    Object n = next;
	    next = null;
	    return n;
	}

	public void remove() {
	    throw new UnsupportedOperationException();
	}

    };
   }