freemarker.ext.beans.JRebelClassChangeNotifier Maven / Gradle / Ivy

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Google App Engine compliant variation of FreeMarker. FreeMarker is a "template engine"; a generic tool to generate text output based on templates.

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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 freemarker.ext.beans;

import java.lang.ref.WeakReference;

import org.zeroturnaround.javarebel.ClassEventListener;
import org.zeroturnaround.javarebel.ReloaderFactory;

class JRebelClassChangeNotifier implements ClassChangeNotifier {

    static void testAvailability() {
        ReloaderFactory.getInstance();
    }

    public void subscribe(ClassIntrospector classIntrospector) {
        ReloaderFactory.getInstance().addClassReloadListener(
                new ClassIntrospectorCacheInvalidator(classIntrospector));
    }

    private static class ClassIntrospectorCacheInvalidator
            implements ClassEventListener {
        private final WeakReference ref;

        ClassIntrospectorCacheInvalidator(ClassIntrospector w) {
            ref = new WeakReference(w);
        }

        public void onClassEvent(int eventType, Class pClass) {
            ClassIntrospector ci = (ClassIntrospector) ref.get();
            if (ci == null) {
                ReloaderFactory.getInstance().removeClassReloadListener(this);
            } else if (eventType == ClassEventListener.EVENT_RELOADED) {
                ci.remove(pClass);
            }
        }
    }

}