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Diffstat (limited to 'branches/sca-java-2.0-M4/modules/sca-api/src/main/java/org/oasisopen/sca/client/impl')
-rw-r--r-- | branches/sca-java-2.0-M4/modules/sca-api/src/main/java/org/oasisopen/sca/client/impl/SCAClientFactoryFinder.java | 241 |
1 files changed, 241 insertions, 0 deletions
diff --git a/branches/sca-java-2.0-M4/modules/sca-api/src/main/java/org/oasisopen/sca/client/impl/SCAClientFactoryFinder.java b/branches/sca-java-2.0-M4/modules/sca-api/src/main/java/org/oasisopen/sca/client/impl/SCAClientFactoryFinder.java new file mode 100644 index 0000000000..5137f8a658 --- /dev/null +++ b/branches/sca-java-2.0-M4/modules/sca-api/src/main/java/org/oasisopen/sca/client/impl/SCAClientFactoryFinder.java @@ -0,0 +1,241 @@ +/* + * Copyright(C) OASIS(R) 2005,2009. All Rights Reserved. + * OASIS trademark, IPR and other policies apply. + */ +package org.oasisopen.sca.client.impl; + +import java.io.BufferedReader; +import java.io.Closeable; +import java.io.IOException; +import java.io.InputStream; +import java.io.InputStreamReader; +import java.net.URI; +import java.net.URL; +import java.util.Properties; + +import org.oasisopen.sca.SCARuntimeException; +import org.oasisopen.sca.client.SCAClientFactory; + +/** + * This is a default class that returns an SCAClientFactory implementation - + * this class can be replaced by a vendor implementation. + * + * @see SCAClientFactory + * @author OASIS Open + */ +public class SCAClientFactoryFinder { + + /** + * The name of the System Property used to determine the SPI implementation + * to use for the SCAClientFactory. + */ + private static final String SCA_CLIENT_FACTORY_PROVIDER_KEY = SCAClientFactory.class.getName(); + + /** + * The name of the file loaded from the ClassPath to determine 2488 the SPI + * implementation to use for the SCAClientFactory. 2489 + */ + private static final String SCA_CLIENT_FACTORY_PROVIDER_META_INF_SERVICE = "META-INF/services/" + SCA_CLIENT_FACTORY_PROVIDER_KEY; + + /** + * Private Constructor. + */ + private SCAClientFactoryFinder() { + } + + /** + * Creates an instance of the SCAClientFactory implementation. This + * discovers the SCAClientFactory implementation and instantiates the + * provider's implementation. + * + * @param properties Properties that may be used when creating a new + * instance of the SCAClient + * @param classLoader ClassLoader that may be used when creating a new + * instance of the SCAClient + * @return new instance of the SCAClientFactory + * @throws SCARuntimeException Failed to create SCAClientFactory + * implementation. + */ + public static SCAClientFactory find(Properties properties, ClassLoader classLoader, URI domainURI) { + if (classLoader == null) { + classLoader = getThreadContextClassLoader(); + if (classLoader == null) { + classLoader = SCAClientFactoryFinder.class.getClassLoader(); + } + } + final String factoryImplClassName = discoverProviderFactoryImplClass(properties, classLoader); + final Class<? extends SCAClientFactory> factoryImplClass = loadProviderFactoryClass(factoryImplClassName, classLoader); + final SCAClientFactory factory = instantiateSCAClientFactoryClass(factoryImplClass, domainURI); + return factory; + } + + /** + * Gets the Context ClassLoader for the current Thread. + * + * @return The Context ClassLoader for the current Thread. + */ + private static ClassLoader getThreadContextClassLoader() { + final ClassLoader threadClassLoader = Thread.currentThread().getContextClassLoader(); + return threadClassLoader; + } + + /** + * Attempts to discover the class name for the SCAClientFactory + * implementation from the specified Properties, the System Properties or + * the specified ClassLoader. + * + * @return The class name of the SCAClientFactory implementation + * @throw SCARuntimeException Failed to find implementation for + * SCAClientFactory. + */ + private static String discoverProviderFactoryImplClass(Properties properties, ClassLoader classLoader) throws SCARuntimeException { + String providerClassName = checkPropertiesForSPIClassName(properties); + if (providerClassName != null) { + return providerClassName; + } + + providerClassName = checkPropertiesForSPIClassName(System.getProperties()); + if (providerClassName != null) { + return providerClassName; + } + + return checkMETAINFServicesForClassName(classLoader); + } + + /** + * Attempts to find the class name for the SCAClientFactory implementation + * from the specified Properties. + * + * @return The class name for the SCAClientFactory implementation or + * <code>null</code> if not found. + */ + private static String checkPropertiesForSPIClassName(Properties properties) { + if (properties == null) { + return null; + } + + final String providerClassName = properties.getProperty(SCA_CLIENT_FACTORY_PROVIDER_KEY); + if (providerClassName != null && providerClassName.length() > 0) { + return providerClassName; + } + + return null; + } + + /** + * Attempts to find the class name for the SCAClientFactory implementation + * from the META-INF/services directory + * + * @return The class name for the SCAClientFactory implementation or + * <code>null</code> if not found. + */ + private static String checkMETAINFServicesForClassName(ClassLoader cl) { + final URL url = cl.getResource(SCA_CLIENT_FACTORY_PROVIDER_META_INF_SERVICE); + if (url == null) { + return null; + } + + InputStream in = null; + try { + in = url.openStream(); + BufferedReader reader = null; + try { + reader = new BufferedReader(new InputStreamReader(in, "UTF-8")); + + String line; + while ((line = readNextLine(reader)) != null) { + if (!line.startsWith("#") && line.length() > 0) { + return line; + } + } + return null; + } finally { + closeStream(reader); + } + } catch (IOException ex) { + throw new SCARuntimeException("Failed to discover SCAClientFactory provider", ex); + } finally { + closeStream(in); + } + } + + /** + * Reads the next line from the reader and returns the trimmed version of + * that line + * + * @param reader The reader from which to read the next line + * @return The trimmed next line or <code>null</code> if the end of the + * stream has been reached + * @throws IOException I/O error occurred while reading from Reader + */ + private static String readNextLine(BufferedReader reader) throws IOException { + + String line = reader.readLine(); + if (line != null) { + line = line.trim(); + } + return line; + } + + /** + * Loads the specified SCAClientFactory implementation class. + * + * @param factoryImplClassName The name of the SCAClientFactory + * Implementation class to load + * @return The specified SCAClientFactory Implementation class + * @throws SCARuntimeException Failed to load the SCAClientFactory + * implementation class + */ + private static Class<? extends SCAClientFactory> loadProviderFactoryClass(String factoryImplClassName, ClassLoader classLoader) + throws SCARuntimeException { + + try { + final Class<?> providerClass = classLoader.loadClass(factoryImplClassName); + final Class<? extends SCAClientFactory> providerFactoryClass = providerClass.asSubclass(SCAClientFactory.class); + return providerFactoryClass; + } catch (ClassNotFoundException ex) { + throw new SCARuntimeException("Failed to load SCAClientFactory implementation class " + factoryImplClassName, ex); + } catch (ClassCastException ex) { + throw new SCARuntimeException("Loaded SCAClientFactory implementation class " + factoryImplClassName + + " is not a subclass of " + + SCAClientFactory.class.getName(), ex); + } + } + + /** + * Instantiate an instance of the specified SCAClientFactory implementation + * class. + * + * @param factoryImplClass The SCAClientFactory implementation class to + * instantiate. + * @param domainURI + * @return An instance of the SCAClientFactory implementation class + * @throws SCARuntimeException Failed to instantiate the specified specified + * SCAClientFactory implementation class + */ + private static SCAClientFactory instantiateSCAClientFactoryClass(Class<? extends SCAClientFactory> factoryImplClass, URI domainURI) throws SCARuntimeException { + + try { + final SCAClientFactory provider = factoryImplClass.getConstructor(URI.class).newInstance(domainURI); + return provider; + } catch (Throwable ex) { + ex.printStackTrace(); + throw new SCARuntimeException("Failed to instantiate SCAClientFactory implementation class " + factoryImplClass, ex); + } + } + + /** + * Utility method for closing Closeable Object. + * + * @param closeable The Object to close. + */ + private static void closeStream(Closeable closeable) { + if (closeable != null) { + try { + closeable.close(); + } catch (IOException ex) { + throw new SCARuntimeException("Failed to close stream", ex); + } + } + } +} |