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java/org/apache/naming/factory/FactoryBase.java

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+/*
+ * 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.naming.factory;
+
+import java.util.Hashtable;
+
+import javax.naming.Context;
+import javax.naming.Name;
+import javax.naming.NamingException;
+import javax.naming.RefAddr;
+import javax.naming.Reference;
+import javax.naming.spi.ObjectFactory;
+
+import org.apache.naming.StringManager;
+
+/**
+ * Abstract base class that provides common functionality required by
+ * sub-classes. This class exists primarily to reduce code duplication.
+ */
+public abstract class FactoryBase implements ObjectFactory {
+
+    private static final StringManager sm = StringManager.getManager(FactoryBase.class);
+
+    /**
+     * Creates a new object instance.
+     *
+     * @param obj The reference object describing the object to create
+     */
+    @Override
+    public final Object getObjectInstance(Object obj, Name name, Context nameCtx,
+            Hashtable<?,?> environment) throws Exception {
+
+        if (isReferenceTypeSupported(obj)) {
+            Reference ref = (Reference) obj;
+
+            Object linked = getLinked(ref);
+            if (linked != null) {
+                return linked;
+            }
+
+            ObjectFactory factory = null;
+            RefAddr factoryRefAddr = ref.get(Constants.FACTORY);
+            if (factoryRefAddr != null) {
+                // Using the specified factory
+                String factoryClassName = factoryRefAddr.getContent().toString();
+                // Loading factory
+                ClassLoader tcl = Thread.currentThread().getContextClassLoader();
+                Class<?> factoryClass = null;
+                try {
+                    if (tcl != null) {
+                        factoryClass = tcl.loadClass(factoryClassName);
+                    } else {
+                        factoryClass = Class.forName(factoryClassName);
+                    }
+                } catch(ClassNotFoundException e) {
+                    NamingException ex = new NamingException(sm.getString("factoryBase.factoryClassError"));
+                    ex.initCause(e);
+                    throw ex;
+                }
+                try {
+                    factory = (ObjectFactory) factoryClass.getConstructor().newInstance();
+                } catch(Throwable t) {
+                    if (t instanceof NamingException) {
+                        throw (NamingException) t;
+                    }
+                    if (t instanceof ThreadDeath) {
+                        throw (ThreadDeath) t;
+                    }
+                    if (t instanceof VirtualMachineError) {
+                        throw (VirtualMachineError) t;
+                    }
+                    NamingException ex = new NamingException(sm.getString("factoryBase.factoryCreationError"));
+                    ex.initCause(t);
+                    throw ex;
+                }
+            } else {
+                // Check for a default factory
+                factory = getDefaultFactory(ref);
+            }
+
+            if (factory != null) {
+                return factory.getObjectInstance(obj, name, nameCtx, environment);
+            } else {
+                throw new NamingException(sm.getString("factoryBase.instanceCreationError"));
+            }
+        }
+
+        return null;
+    }
+
+
+    /**
+     * Determines if this factory supports processing the provided reference
+     * object.
+     *
+     * @param obj   The object to be processed
+     *
+     * @return <code>true</code> if this factory can process the object,
+     *         otherwise <code>false</code>
+     */
+    protected abstract boolean isReferenceTypeSupported(Object obj);
+
+    /**
+     * If a default factory is available for the given reference type, create
+     * the default factory.
+     *
+     * @param ref   The reference object to be processed
+     *
+     * @return  The default factory for the given reference object or
+     *          <code>null</code> if no default factory exists.
+     *
+     * @throws NamingException  If the default factory cannot be created
+     */
+    protected abstract ObjectFactory getDefaultFactory(Reference ref)
+            throws NamingException;
+
+    /**
+     * If this reference is a link to another JNDI object, obtain that object.
+     *
+     * @param ref   The reference object to be processed
+     *
+     * @return  The linked object or <code>null</code> if linked objects are
+     *          not supported by or not configured for this reference object
+     * @throws NamingException Error accessing linked object
+     */
+    protected abstract Object getLinked(Reference ref) throws NamingException;
+}