1 files changed, 226 insertions, 0 deletions
diff --git a/sca-java-2.x/tags/2.0.1-RC1/modules/extensibility/src/main/java/org/apache/tuscany/sca/extensibility/ServiceHelper.java b/sca-java-2.x/tags/2.0.1-RC1/modules/extensibility/src/main/java/org/apache/tuscany/sca/extensibility/ServiceHelper.java
new file mode 100644
index 0000000000..7f38aa6d06
--- /dev/null
+++ b/sca-java-2.x/tags/2.0.1-RC1/modules/extensibility/src/main/java/org/apache/tuscany/sca/extensibility/ServiceHelper.java
@@ -0,0 +1,226 @@
+/*
+ * 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.extensibility;
+
+import java.lang.reflect.Constructor;
+import java.lang.reflect.InvocationHandler;
+import java.lang.reflect.Method;
+import java.lang.reflect.Proxy;
+import java.util.Collection;
+import java.util.Map;
+
+import org.apache.tuscany.sca.core.ExtensionPointRegistry;
+import org.apache.tuscany.sca.core.LifeCycleListener;
+
+/**
+ * A helper for handling service lifecycle and instantiations
+ * @tuscany.spi.extension.asclient
+ */
+public class ServiceHelper {
+    private ServiceHelper() {
+    }
+
+    /**
+     * Start the service instance
+     * @param instance
+     */
+    public static boolean start(Object instance) {
+        if (instance instanceof LifeCycleListener) {
+            ((LifeCycleListener)instance).start();
+            return true;
+        }
+        return false;
+    }
+
+    /**
+     * Stop the service instance
+     * @param instance
+     */
+    public static boolean stop(Object instance) {
+        if (instance instanceof LifeCycleListener) {
+            ((LifeCycleListener)instance).stop();
+            return true;
+        }
+        return false;
+    }
+
+    /**
+     * Stop a collection of service instances
+     * @param instances
+     */
+    public static void stop(Collection<? extends Object> instances) {
+        if (instances == null) {
+            return;
+        }
+        for (Object instance : instances) {
+            if (instance instanceof LifeCycleListener) {
+                ((LifeCycleListener)instance).stop();
+            }
+        }
+    }
+
+    /**
+     * Create a service instance with one parameter
+     * @param cls The service type
+     * @param parameterType The parameter type
+     * @param parameter The parameter value
+     * @return The newly created service instance
+     * @throws Exception
+     */
+    public static <T> T newInstance(Class<T> cls, Class<?> parameterType, Object parameter) throws Exception {
+        Constructor<T> constructor = cls.getConstructor(parameterType);
+        return constructor.newInstance(parameter);
+    }
+
+    /**
+     * Create a service instance with an array of parameters
+     * @param cls The service type
+     * @param parameterTypes An array of parameter types
+     * @param parameters An array of parameter values
+     * @return The newly created service instance 
+     * @throws Exception
+     */
+    public static <T> T newInstance(Class<T> cls, Class<?> parameterTypes[], Object... parameters) throws Exception {
+        Constructor<T> constructor = cls.getConstructor(parameterTypes);
+        return constructor.newInstance(parameters);
+    }
+
+    /**
+     * Create a service instance with the default no-arg constructor
+     * @param cls The service type
+     * @return The newly created service instance
+     * @throws Exception
+     */
+    public static <T> T newInstance(Class<T> cls) throws Exception {
+        Constructor<T> constructor = cls.getConstructor();
+        return constructor.newInstance();
+    }
+
+    private final static Class<?>[] ARG_TYPES = new Class<?>[] {ExtensionPointRegistry.class, Map.class};
+
+    /**
+     * Create a service instance from the service declaration
+     * @param <T>
+     * @param registry The extension point registry
+     * @param sd The service declaration
+     * @return The newly created service instance
+     * @throws Exception
+     */
+    public static <T> T newInstance(ExtensionPointRegistry registry, ServiceDeclaration sd) throws Exception {
+        Class<T> cls = (Class<T>)sd.loadClass();
+        T instance = null;
+        try {
+            // Try constructor(ExtensionPointRegistry.class)
+            instance = newInstance(cls, ExtensionPointRegistry.class, registry);
+        } catch (NoSuchMethodException e) {
+            try {
+                // Try Try constructor(ExtensionPointRegistry.class, Map.class)
+                instance = newInstance(cls, ARG_TYPES, registry, sd.getAttributes());
+            } catch (NoSuchMethodException e1) {
+                // Try constructor()
+                instance = newInstance(cls);
+            }
+        }
+        return instance;
+    }
+
+    public static <T> T newLazyInstance(ExtensionPointRegistry registry, ServiceDeclaration sd, Class<T> serviceType) {
+        return serviceType.cast(Proxy.newProxyInstance(serviceType.getClassLoader(),
+                                                       new Class<?>[] {serviceType, LifeCycleListener.class},
+                                                       new InvocationHandlerImpl(registry, serviceType, sd)));
+    }
+
+    private static class InvocationHandlerImpl implements InvocationHandler {
+        private ExtensionPointRegistry registry;
+        private Class<?> type;
+        private ServiceDeclaration sd;
+        private Object instance;
+
+        private final static Method STOP_METHOD = getMethod(LifeCycleListener.class, "stop");
+        private final static Method START_METHOD = getMethod(LifeCycleListener.class, "start");
+        private final static Method EQUALS_METHOD = getMethod(Object.class, "equals");
+        private final static Method HASHCODE_METHOD = getMethod(Object.class, "hashCode");
+        private final static Method TOSTRING_METHOD = getMethod(Object.class, "toString");
+
+        private static Method getMethod(Class<?> type, String name) {
+            Method[] methods = type.getMethods();
+            for (Method method : methods) {
+                if (name.equals(method.getName())) {
+                    return method;
+                }
+            }
+            return null;
+        }
+
+        public InvocationHandlerImpl(ExtensionPointRegistry registry, Class<?> type, ServiceDeclaration sd) {
+            super();
+            this.registry = registry;
+            this.sd = sd;
+            this.type = type;
+        }
+
+        private Object getAttribute(Method method) throws Exception {
+            if (method.getParameterTypes().length != 0) {
+                return null;
+            }
+            String name = method.getName();
+            if (name.equals("getModelType") && method.getReturnType() == Class.class) {
+                return sd.loadClass(sd.getAttributes().get("model"));
+            } else if (name.equals("getArtifactType")) {
+                return ServiceDeclarationParser.getQName(sd.getAttributes().get("qname"));
+            }
+            return null;
+        }
+
+        public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
+            synchronized (this) {
+                // Check if the method is to get the qname/model attribute
+                Object value = getAttribute(method);
+                if (value != null) {
+                    return value;
+                }
+                if (instance == null && method.getDeclaringClass() == type) {
+                    // Only initialize the instance when a method on the service type is invoked
+                    instance = newInstance(registry, sd);
+                    start(instance);
+                }
+                if (method.equals(EQUALS_METHOD)) {
+                    return proxy == args[0];
+                } else if (method.equals(HASHCODE_METHOD)) {
+                    return System.identityHashCode(proxy);
+                } else if (method.equals(TOSTRING_METHOD)) {
+                    return "Proxy: " + sd.toString();
+                }
+                if (instance == null) {
+                    return null;
+                }
+            }
+            if (method.equals(STOP_METHOD)) {
+                stop(instance);
+                return null;
+            } else if (method.equals(START_METHOD)) {
+                // Skip the start()
+                return null;
+            } else {
+                return method.invoke(instance, args);
+            }
+        }
+    }
+}