svn commit: r929169 - in /myfaces/extensions/cdi/trunk/core/api/src/main/java/org/apache/myfaces/extensions/cdi/core/api/tools/annotate: ./ DefaultAnnotation.java

[st...@apache.org]

Author: struberg
Date: Tue Mar 30 15:25:22 2010
New Revision: 929169

URL: http://svn.apache.org/viewvc?rev=929169&view=rev
Log:
EXTCDI-16 add DefaultAnnotation facility

Added:
    myfaces/extensions/cdi/trunk/core/api/src/main/java/org/apache/myfaces/extensions/cdi/core/api/tools/annotate/
    myfaces/extensions/cdi/trunk/core/api/src/main/java/org/apache/myfaces/extensions/cdi/core/api/tools/annotate/DefaultAnnotation.java

Added: myfaces/extensions/cdi/trunk/core/api/src/main/java/org/apache/myfaces/extensions/cdi/core/api/tools/annotate/DefaultAnnotation.java
URL: http://svn.apache.org/viewvc/myfaces/extensions/cdi/trunk/core/api/src/main/java/org/apache/myfaces/extensions/cdi/core/api/tools/annotate/DefaultAnnotation.java?rev=929169&view=auto
==============================================================================
--- myfaces/extensions/cdi/trunk/core/api/src/main/java/org/apache/myfaces/extensions/cdi/core/api/tools/annotate/DefaultAnnotation.java (added)
+++ myfaces/extensions/cdi/trunk/core/api/src/main/java/org/apache/myfaces/extensions/cdi/core/api/tools/annotate/DefaultAnnotation.java Tue Mar 30 15:25:22 2010
@@ -0,0 +1,72 @@
+/*
+ * 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.myfaces.extensions.cdi.api.tools.annotate;
+
+import java.lang.annotation.Annotation;
+import java.lang.reflect.InvocationHandler;
+import java.lang.reflect.Method;
+import java.lang.reflect.Proxy;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+
+/**
+ * <p>A small helper class to create a Annotation instance of the given annotation class
+ * via {@link java.lang.reflect.Proxy}. The annotation literal gets filled with the default values.</p>
+ *
+ * <p>usage:</p>
+ * <pre>
+ * Class<? extends annotation> annotationClass = ...;
+ * Annotation a = DefaultAnnotation.of(annotationClass)
+ * </pre>
+ * <a href="mailto:struberg@yahoo.de">Mark Struberg</a>
+*/
+public class DefaultAnnotation implements InvocationHandler
+{
+    
+    static volatile Map<Class<? extends Annotation>, Annotation> annotationCache 
+                        = new ConcurrentHashMap<Class<? extends Annotation>, Annotation>();
+    
+    public static Annotation of(Class<? extends Annotation> annotationClass) 
+    {
+        Annotation annon = annotationCache.get(annotationClass);
+        
+        if (annon == null)
+        {
+            // switch into paranoia mode
+            synchronized (annotationCache) 
+            {
+                annon = annotationCache.get(annotationClass);
+                if (annon == null)
+                {
+                    annon = (Annotation) Proxy.newProxyInstance(annotationClass.getClassLoader(), 
+                            new Class[] {annotationClass}, 
+                            new DefaultAnnotation());
+                    annotationCache.put(annotationClass, annon);
+                }
+            }
+        }
+        
+        return annon;
+    }
+    
+    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable 
+    {
+        return method.getDefaultValue();
+    }
+}