tomcat生命周期管理接口Lifecycle

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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;


/**
* Common interface for component life cycle methods. Catalina components
* may, but are not required to, implement this interface (as well as the
* appropriate interface(s) for the functionality they support) in order to
* provide a consistent mechanism to start and stop the component.
*
* @author Craig R. McClanahan
* @version $Revision: 467222 $ $Date: 2006-10-24 05:17:11 +0200 (Tue, 24 Oct 2006) $
*/

public interface Lifecycle {


// ----------------------------------------------------- Manifest Constants


/**
* The LifecycleEvent type for the "component init" event.
*/
public static final String INIT_EVENT = "init";


/**
* The LifecycleEvent type for the "component start" event.
*/
public static final String START_EVENT = "start";


/**
* The LifecycleEvent type for the "component before start" event.
*/
public static final String BEFORE_START_EVENT = "before_start";


/**
* The LifecycleEvent type for the "component after start" event.
*/
public static final String AFTER_START_EVENT = "after_start";


/**
* The LifecycleEvent type for the "component stop" event.
*/
public static final String STOP_EVENT = "stop";


/**
* The LifecycleEvent type for the "component before stop" event.
*/
public static final String BEFORE_STOP_EVENT = "before_stop";


/**
* The LifecycleEvent type for the "component after stop" event.
*/
public static final String AFTER_STOP_EVENT = "after_stop";


/**
* The LifecycleEvent type for the "component destroy" event.
*/
public static final String DESTROY_EVENT = "destroy";


/**
* The LifecycleEvent type for the "periodic" event.
*/
public static final String PERIODIC_EVENT = "periodic";


// --------------------------------------------------------- Public Methods


/**
* Add a LifecycleEvent listener to this component.
*
* @param listener The listener to add
*/
public void addLifecycleListener(LifecycleListener listener);


/**
* Get the lifecycle listeners associated with this lifecycle. If this
* Lifecycle has no listeners registered, a zero-length array is returned.
*/
public LifecycleListener[] findLifecycleListeners();


/**
* Remove a LifecycleEvent listener from this component.
*
* @param listener The listener to remove
*/
public void removeLifecycleListener(LifecycleListener listener);


/**
* Prepare for the beginning of active use of the public methods of this
* component. This method should be called before any of the public
* methods of this component are utilized. It should also send a
* LifecycleEvent of type START_EVENT to any registered listeners.
*
* @exception LifecycleException if this component detects a fatal error
* that prevents this component from being used
*/
public void start() throws LifecycleException;


/**
* Gracefully terminate the active use of the public methods of this
* component. This method should be the last one called on a given
* instance of this component. It should also send a LifecycleEvent
* of type STOP_EVENT to any registered listeners.
*
* @exception LifecycleException if this component detects a fatal error
* that needs to be reported
*/
public void stop() throws LifecycleException;


}