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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.catalina;

import java.beans.PropertyChangeListener;

/**
 * A Loader represents a Java ClassLoader implementation that can
 * be used by a Container to load class files (within a repository associated
 * with the Loader) that are designed to be reloaded upon request, as well as
 * a mechanism to detect whether changes have occurred in the underlying
 * repository.
 * 

* In order for a Loader implementation to successfully operate * with a Context implementation that implements reloading, it * must obey the following constraints: *

    *
  • Must implement Lifecycle so that the Context can indicate * that a new class loader is required. *
  • The start() method must unconditionally create a new * ClassLoader implementation. *
  • The stop() method must throw away its reference to the * ClassLoader previously utilized, so that the class loader, * all classes loaded by it, and all objects of those classes, can be * garbage collected. *
  • Must allow a call to stop() to be followed by a call to * start() on the same Loader instance. *
  • Based on a policy chosen by the implementation, must call the * Context.reload() method on the owning Context * when a change to one or more of the class files loaded by this class * loader is detected. *
* * @author Craig R. McClanahan */ public interface Loader { /** * Execute a periodic task, such as reloading, etc. This method will be * invoked inside the classloading context of this container. Unexpected * throwables will be caught and logged. */ public void backgroundProcess(); /** * @return the Java class loader to be used by this Container. */ public ClassLoader getClassLoader(); /** * @return the Context with which this Loader has been associated. */ public Context getContext(); /** * Set the Context with which this Loader has been associated. * * @param context The associated Context */ public void setContext(Context context); /** * @return the "follow standard delegation model" flag used to configure * our ClassLoader. */ public boolean getDelegate(); /** * Set the "follow standard delegation model" flag used to configure * our ClassLoader. * * @param delegate The new flag */ public void setDelegate(boolean delegate); /** * @return the reloadable flag for this Loader. */ public boolean getReloadable(); /** * Set the reloadable flag for this Loader. * * @param reloadable The new reloadable flag */ public void setReloadable(boolean reloadable); /** * Add a property change listener to this component. * * @param listener The listener to add */ public void addPropertyChangeListener(PropertyChangeListener listener); /** * Has the internal repository associated with this Loader been modified, * such that the loaded classes should be reloaded? * * @return true when the repository has been modified, * false otherwise */ public boolean modified(); /** * Remove a property change listener from this component. * * @param listener The listener to remove */ public void removePropertyChangeListener(PropertyChangeListener listener); }




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