1 files changed, 164 insertions, 0 deletions
diff --git a/sca-java-1.x/branches/sca-java-1.0.1/modules/extension-helper/src/main/java/org/apache/tuscany/sca/extension/helper/impl/DiscoveryUtils.java b/sca-java-1.x/branches/sca-java-1.0.1/modules/extension-helper/src/main/java/org/apache/tuscany/sca/extension/helper/impl/DiscoveryUtils.java
new file mode 100644
index 0000000000..7f25db0620
--- /dev/null
+++ b/sca-java-1.x/branches/sca-java-1.0.1/modules/extension-helper/src/main/java/org/apache/tuscany/sca/extension/helper/impl/DiscoveryUtils.java
@@ -0,0 +1,164 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ * 
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.    
+ */
+
+package org.apache.tuscany.sca.extension.helper.impl;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.lang.reflect.Constructor;
+import java.lang.reflect.InvocationTargetException;
+import java.net.URL;
+import java.util.ArrayList;
+import java.util.Enumeration;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+
+import org.apache.tuscany.sca.core.ExtensionPointRegistry;
+
+/**
+ * Discovers Activators in the classpath using the J2SE
+ * jar file extensions for Service Provider discovery
+ */
+public class DiscoveryUtils {
+
+    public static <T> List<T> discoverActivators(Class<T> activatorClass, ClassLoader classLoader, ExtensionPointRegistry registry) {
+        Set<Class> activatorClasses = getServiceClasses(classLoader, activatorClass);
+        List<T> activators = new ArrayList<T>();
+        for (Class<T> c : activatorClasses) {
+            try {
+                activators.add(c.cast(instantiateActivator(c, registry)));
+            } catch (Throwable e) {
+                e.printStackTrace(); // TODO: log
+            }
+        }
+        return activators;
+    }
+
+    static Object instantiateActivator(Class activator, ExtensionPointRegistry registry) {
+        Constructor[] cs = activator.getConstructors();
+        if (cs.length != 1) {
+            throw new RuntimeException("Activator must have only one constructors");
+        }
+        
+        Class<?>[] paramTypes = cs[0].getParameterTypes();
+        Object[] extensions = new Object[paramTypes.length];
+
+        for (int i=0; i< paramTypes.length; i++) {
+            if ("org.apache.tuscany.sca.host.http.ServletHost".equals(paramTypes[i].getName())) {
+                extensions[i] = getServletHost(registry);
+            } else {
+                extensions[i] = registry.getExtensionPoint(paramTypes[i]);
+            }
+        }
+        
+        try {
+
+            return cs[0].newInstance(extensions);
+
+        } catch (Exception e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    private static Object getServletHost(ExtensionPointRegistry registry) {
+        try {
+
+            Class<?> servletHostEPClass = Class.forName("org.apache.tuscany.sca.host.http.ServletHostExtensionPoint");
+            Object servletHostEP = registry.getExtensionPoint(servletHostEPClass);
+            Class<?> extensibleServletHost = Class.forName("org.apache.tuscany.sca.host.http.ExtensibleServletHost");
+            return extensibleServletHost.getConstructor(new Class[] {servletHostEPClass}).newInstance(servletHostEP);
+
+        } catch (ClassNotFoundException e) {
+            throw new RuntimeException(e);
+        } catch (IllegalArgumentException e) {
+            throw new RuntimeException(e);
+        } catch (SecurityException e) {
+            throw new RuntimeException(e);
+        } catch (InstantiationException e) {
+            throw new RuntimeException(e);
+        } catch (IllegalAccessException e) {
+            throw new RuntimeException(e);
+        } catch (InvocationTargetException e) {
+            throw new RuntimeException(e);
+        } catch (NoSuchMethodException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    static Set<Class> getServiceClasses(ClassLoader classLoader, Class name) {
+        try {
+
+            Set<Class> set = new HashSet<Class>();
+            Enumeration<URL> urls = classLoader.getResources("META-INF/services/" + name.getName());
+            while (urls.hasMoreElements()) {
+                URL url = urls.nextElement();
+                Set<String> services = getServiceClassNames(url);
+                if (services != null) {
+                    for (String className : services) {
+                        try {
+                            set.add(Class.forName(className, true, classLoader));
+                        } catch (Throwable e) {
+                            // TODO: log 
+                        }
+                    }
+                }
+            }
+            return set;
+
+        } catch (IOException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    static Set<String> getServiceClassNames(URL url) throws IOException {
+        Set<String> names = new HashSet<String>();
+        InputStream is = url.openStream();
+        BufferedReader reader = null;
+        try {
+            reader = new BufferedReader(new InputStreamReader(is));
+            while (true) {
+                String line = reader.readLine();
+                if (line == null) {
+                    break;
+                }
+                line = line.trim();
+                if (!line.startsWith("#") && !"".equals(line)) {
+                    names.add(line.trim());
+                }
+            }
+        } finally {
+            if (reader != null) {
+                reader.close();
+            }
+            
+            if (is != null){
+                try {
+                    is.close();
+                } catch( IOException ioe) {
+                    //ignore
+                }
+            }
+        }
+        return names;
+    }
+
+}