1 files changed, 238 insertions, 0 deletions
diff --git a/tags/java/sca/2.0-M3-RC5/modules/sca-api/src/main/java/org/oasisopen/sca/client/impl/SCAClientFactoryFinder.java b/tags/java/sca/2.0-M3-RC5/modules/sca-api/src/main/java/org/oasisopen/sca/client/impl/SCAClientFactoryFinder.java
new file mode 100644
index 0000000000..c13e4e9142
--- /dev/null
+++ b/tags/java/sca/2.0-M3-RC5/modules/sca-api/src/main/java/org/oasisopen/sca/client/impl/SCAClientFactoryFinder.java
@@ -0,0 +1,238 @@
+/* 
+ * 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.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) {
+        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);
+        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.
+     * @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) throws SCARuntimeException {
+
+        try {
+            final SCAClientFactory provider = factoryImplClass.newInstance();
+            return provider;
+        } catch (Throwable ex) {
+            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);
+            }
+        }
+    }
+}