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Posted to commits@deltaspike.apache.org by st...@apache.org on 2012/04/24 21:03:55 UTC
git commit: DELTASPIKE-55 add an initial version of
AnnotationInstanceProvider
Updated Branches:
refs/heads/master 35eb43892 -> d0e5199d3
DELTASPIKE-55 add an initial version of AnnotationInstanceProvider
Project: http://git-wip-us.apache.org/repos/asf/incubator-deltaspike/repo
Commit: http://git-wip-us.apache.org/repos/asf/incubator-deltaspike/commit/d0e5199d
Tree: http://git-wip-us.apache.org/repos/asf/incubator-deltaspike/tree/d0e5199d
Diff: http://git-wip-us.apache.org/repos/asf/incubator-deltaspike/diff/d0e5199d
Branch: refs/heads/master
Commit: d0e5199d33120f459e3aebbc9a539988e39aed8d
Parents: 35eb438
Author: Mark Struberg <st...@apache.org>
Authored: Tue Apr 24 21:03:02 2012 +0200
Committer: Mark Struberg <st...@apache.org>
Committed: Tue Apr 24 21:03:02 2012 +0200
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.../util/metadata/AnnotationInstanceProvider.java | 244 +++++++++++++++
1 files changed, 244 insertions(+), 0 deletions(-)
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http://git-wip-us.apache.org/repos/asf/incubator-deltaspike/blob/d0e5199d/deltaspike/core/api/src/main/java/org/apache/deltaspike/core/util/metadata/AnnotationInstanceProvider.java
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diff --git a/deltaspike/core/api/src/main/java/org/apache/deltaspike/core/util/metadata/AnnotationInstanceProvider.java b/deltaspike/core/api/src/main/java/org/apache/deltaspike/core/util/metadata/AnnotationInstanceProvider.java
new file mode 100644
index 0000000..e4445ca
--- /dev/null
+++ b/deltaspike/core/api/src/main/java/org/apache/deltaspike/core/util/metadata/AnnotationInstanceProvider.java
@@ -0,0 +1,244 @@
+/*
+ * 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.deltaspike.core.util.metadata;
+
+
+import java.io.Serializable;
+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.WeakHashMap;
+import java.util.concurrent.ConcurrentHashMap;
+
+import org.apache.deltaspike.core.util.ClassUtils;
+
+/**
+ * <p>A small helper class to create an Annotation instance of the given annotation class
+ * via {@link java.lang.reflect.Proxy}. The annotation literal gets filled with the default values.</p>
+ * <p/>
+ * <p>This class can be used to dynamically create Annotations which can be usd in AnnotatedTyp.
+ * This is e.g. the case if you configure an annotation via properties or XML file. In those cases you
+ * cannot use {@link javax.enterprise.util.AnnotationLiteral} because the type is not known at compile time.</p>
+ * <p>usage:</p>
+ * <pre>
+ * String annotationClassName = ...;
+ * Class<? extends annotation> annotationClass =
+ * (Class<? extends Annotation>) ClassUtils.getClassLoader(null).loadClass(annotationClassName);
+ * Annotation a = DefaultAnnotation.of(annotationClass)
+ * </pre>
+ *
+ */
+public class AnnotationInstanceProvider implements Annotation, InvocationHandler, Serializable
+{
+ private static final long serialVersionUID = -2345068201195886173L;
+ private static final Object[] EMPTY_OBJECT_ARRAY = new Object[0];
+
+ // NOTE that this cache needs to be a WeakHashMap in order to prevent a memory leak
+ // (the garbage collector should be able to remove the ClassLoader).
+ private static volatile Map<ClassLoader, Map<String, Annotation>> annotationCache
+ = new WeakHashMap<ClassLoader, Map<String, Annotation>>();
+
+ private Class<? extends Annotation> annotationClass;
+
+
+ /**
+ * Required to use the result of the factory instead of a default implementation
+ * of {@link javax.enterprise.util.AnnotationLiteral}.
+ *
+ * @param annotationClass class of the target annotation
+ */
+ private AnnotationInstanceProvider(Class<? extends Annotation> annotationClass)
+ {
+ this.annotationClass = annotationClass;
+ }
+
+
+ /**
+ * Creates an annotation instance for the given annotation class
+ * @param annotationClass type of the target annotation
+ * @param <T> current type
+ * @return annotation instance for the given type
+ */
+ public static <T extends Annotation> T of(Class<T> annotationClass)
+ {
+ String key = annotationClass.getName();
+
+ Map<String, Annotation> cache = getAnnotationCache();
+
+ Annotation annotation = cache.get(key);
+
+ if (annotation == null)
+ {
+ annotation = initAnnotation(key, annotationClass, cache);
+ }
+
+ return (T) annotation;
+ }
+
+ private static synchronized <T extends Annotation> Annotation initAnnotation(String key,
+ Class<T> annotationClass,
+ Map<String, Annotation> cache)
+ {
+ Annotation annotation = cache.get(key);
+
+ // switch into paranoia mode
+ if (annotation == null)
+ {
+ annotation = (Annotation) Proxy.newProxyInstance(annotationClass.getClassLoader(),
+ new Class[]{annotationClass},
+ new AnnotationInstanceProvider(annotationClass));
+
+ cache.put(key, annotation);
+ }
+
+ return annotation;
+ }
+
+ private static Map<String, Annotation> getAnnotationCache()
+ {
+ ClassLoader classLoader = ClassUtils.getClassLoader(null);
+ Map<String, Annotation> cache = annotationCache.get(classLoader);
+
+ if (cache == null)
+ {
+ cache = init(classLoader);
+ }
+
+ return cache;
+ }
+
+ private static synchronized Map<String, Annotation> init(ClassLoader classLoader)
+ {
+ // switch into paranoia mode
+ Map<String, Annotation> cache = annotationCache.get(classLoader);
+ if (cache == null)
+ {
+ cache = new ConcurrentHashMap<String, Annotation>();
+ annotationCache.put(classLoader, cache);
+ }
+ return cache;
+ }
+
+ /**
+ * {@inheritDoc}
+ */
+ @Override
+ public Object invoke(Object proxy, Method method, Object[] args) throws Exception
+ {
+ if ("hashCode".equals(method.getName()))
+ {
+ return hashCode();
+ }
+ else if ("equals".equals(method.getName()))
+ {
+ return equals(args[0]);
+ }
+ else if ("annotationType".equals(method.getName()))
+ {
+ return annotationType();
+ }
+ else if ("toString".equals(method.getName()))
+ {
+ return toString();
+ }
+
+ return method.getDefaultValue();
+ }
+
+ /**
+ * {@inheritDoc}
+ */
+ @Override
+ public Class<? extends Annotation> annotationType()
+ {
+ return annotationClass;
+ }
+
+ /**
+ * Copied from Apache OWB (javax.enterprise.util.AnnotationLiteral#toString())
+ * with minor changes.
+ *
+ * @return the current state of the annotation as string
+ */
+ @Override
+ public String toString()
+ {
+ Method[] methods = this.annotationClass.getDeclaredMethods();
+
+ StringBuilder sb = new StringBuilder("@" + annotationType().getName() + "(");
+ int length = methods.length;
+
+ for (int i = 0; i < length; i++)
+ {
+ // Member name
+ sb.append(methods[i].getName()).append("=");
+
+ // Member value
+ Object memberValue;
+ try
+ {
+ memberValue = invoke(this, methods[i], EMPTY_OBJECT_ARRAY);
+ }
+ catch (Exception e)
+ {
+ memberValue = "";
+ }
+ sb.append(memberValue);
+
+ if (i < length - 1)
+ {
+ sb.append(",");
+ }
+ }
+
+ sb.append(")");
+
+ return sb.toString();
+ }
+
+ @Override
+ public boolean equals(Object o)
+ {
+ if (this == o)
+ {
+ return true;
+ }
+ if (!(o instanceof AnnotationInstanceProvider))
+ {
+ return false;
+ }
+
+ AnnotationInstanceProvider that = (AnnotationInstanceProvider) o;
+
+ if (!annotationClass.equals(that.annotationClass))
+ {
+ return false;
+ }
+
+ return true;
+ }
+
+ @Override
+ public int hashCode()
+ {
+ return annotationClass.hashCode();
+ }
+}