ClassDeactivator.java

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 * Licensed to the Apache Software Foundation (ASF) under one
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 * to you under the Apache License, Version 2.0 (the
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 * with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.deltaspike.core.spi.activation;

import java.io.Serializable;

/**
 * <p>DeltaSpike allows you to deactivate pre-configured parts (like Extensions, event-broadcasters,...).
 * Therefore DeltaSpike offers {@link ClassDeactivator} and {@link Deactivatable}.</p>
 *
 * <p>A {@link ClassDeactivator} allows to specify deactivated classes (if they implement {@link Deactivatable})
 * which can't be deactivated/customized via std. CDI mechanisms
 * (like the veto-method or alternative/specialized CDI-beans).
 * This might be the case e.g. for CDI Extensions because CDI mechanisms are not available at startup time.</p>
 *
 * <p>Use it mainly to deactivate specific parts explicitly (blacklist approach),
 * if there is an issue with such parts (and waiting for the next release isn't an option).</p>
 *
 * <p>A class-deactivator will be resolved from the environment via the default resolvers or via a custom resolver which
 * allows to use any type of configuration-format. See {@link org.apache.deltaspike.core.api.config.ConfigResolver}
 * for more information about how to configure it. The configuration key is
 * <code>org.apache.deltaspike.core.spi.activation.ClassDeactivator</code></p>
 *
 * <p>All ClassDeactivators will get picked up in order of their ordinal and might explicitly activate or
 * deactivate {@link Deactivatable} classes. Returning a <code>null</code> value means that the ClassDeactivator
 * doesn't care about the Deactivatable class.</p>
 *
 * <p>An implementation has to be stateless.</p>
 */
public interface ClassDeactivator extends Serializable
{
    /**
     * Provides classes which should be deactivated.
     *
     * @param targetClass class which should be checked
     * @return {@link Boolean#FALSE} if class should get activated, {@link Boolean#FALSE} if class must be available
     *         and <code>null</code> to let it as is (defined by default or other
     */
    Boolean isActivated(Class<? extends Deactivatable> targetClass);
}