136 lines
4.3 KiB
Java
136 lines
4.3 KiB
Java
/*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.apache.catalina;
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import java.beans.PropertyChangeListener;
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/**
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* A <b>Loader</b> represents a Java ClassLoader implementation that can
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* be used by a Container to load class files (within a repository associated
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* with the Loader) that are designed to be reloaded upon request, as well as
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* a mechanism to detect whether changes have occurred in the underlying
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* repository.
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* <p>
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* In order for a <code>Loader</code> implementation to successfully operate
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* with a <code>Context</code> implementation that implements reloading, it
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* must obey the following constraints:
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* <ul>
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* <li>Must implement <code>Lifecycle</code> so that the Context can indicate
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* that a new class loader is required.
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* <li>The <code>start()</code> method must unconditionally create a new
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* <code>ClassLoader</code> implementation.
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* <li>The <code>stop()</code> method must throw away its reference to the
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* <code>ClassLoader</code> previously utilized, so that the class loader,
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* all classes loaded by it, and all objects of those classes, can be
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* garbage collected.
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* <li>Must allow a call to <code>stop()</code> to be followed by a call to
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* <code>start()</code> on the same <code>Loader</code> instance.
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* <li>Based on a policy chosen by the implementation, must call the
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* <code>Context.reload()</code> method on the owning <code>Context</code>
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* when a change to one or more of the class files loaded by this class
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* loader is detected.
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* </ul>
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*
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* @author Craig R. McClanahan
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*/
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public interface Loader {
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/**
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* Execute a periodic task, such as reloading, etc. This method will be
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* invoked inside the classloading context of this container. Unexpected
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* throwables will be caught and logged.
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*/
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public void backgroundProcess();
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/**
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* @return the Java class loader to be used by this Container.
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*/
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public ClassLoader getClassLoader();
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/**
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* @return the Context with which this Loader has been associated.
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*/
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public Context getContext();
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/**
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* Set the Context with which this Loader has been associated.
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*
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* @param context The associated Context
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*/
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public void setContext(Context context);
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/**
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* @return the "follow standard delegation model" flag used to configure
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* our ClassLoader.
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*/
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public boolean getDelegate();
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/**
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* Set the "follow standard delegation model" flag used to configure
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* our ClassLoader.
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*
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* @param delegate The new flag
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*/
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public void setDelegate(boolean delegate);
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/**
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* @return the reloadable flag for this Loader.
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*/
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public boolean getReloadable();
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/**
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* Set the reloadable flag for this Loader.
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*
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* @param reloadable The new reloadable flag
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*/
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public void setReloadable(boolean reloadable);
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/**
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* Add a property change listener to this component.
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*
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* @param listener The listener to add
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*/
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public void addPropertyChangeListener(PropertyChangeListener listener);
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/**
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* Has the internal repository associated with this Loader been modified,
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* such that the loaded classes should be reloaded?
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*
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* @return <code>true</code> when the repository has been modified,
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* <code>false</code> otherwise
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*/
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public boolean modified();
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/**
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* Remove a property change listener from this component.
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*
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* @param listener The listener to remove
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*/
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public void removePropertyChangeListener(PropertyChangeListener listener);
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}
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