Java tutorial
/* * 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.commons.pool; /** * A simple base implementation of <code>KeyedObjectPool</code>. * Optional operations are implemented to either do nothing, return a value * indicating it is unsupported or throw {@link UnsupportedOperationException}. * * @author Rodney Waldhoff * @author Sandy McArthur * @version $Revision: 777748 $ $Date: 2009-05-22 20:00:44 -0400 (Fri, 22 May 2009) $ * @since Pool 1.0 */ public abstract class BaseKeyedObjectPool implements KeyedObjectPool { public abstract Object borrowObject(Object key) throws Exception; public abstract void returnObject(Object key, Object obj) throws Exception; public abstract void invalidateObject(Object key, Object obj) throws Exception; /** * Not supported in this base implementation. * Always throws an {@link UnsupportedOperationException}, * subclasses should override this behavior. */ public void addObject(Object key) throws Exception, UnsupportedOperationException { throw new UnsupportedOperationException(); } /** * Not supported in this base implementation. * @return a negative value. */ public int getNumIdle(Object key) throws UnsupportedOperationException { return -1; } /** * Not supported in this base implementation. * @return a negative value. */ public int getNumActive(Object key) throws UnsupportedOperationException { return -1; } /** * Not supported in this base implementation. * @return a negative value. */ public int getNumIdle() throws UnsupportedOperationException { return -1; } /** * Not supported in this base implementation. * @return a negative value. */ public int getNumActive() throws UnsupportedOperationException { return -1; } /** * Not supported in this base implementation. */ public void clear() throws Exception, UnsupportedOperationException { throw new UnsupportedOperationException(); } /** * Not supported in this base implementation. */ public void clear(Object key) throws Exception, UnsupportedOperationException { throw new UnsupportedOperationException(); } /** * Close this pool. * This affects the behavior of <code>isClosed</code> and <code>assertOpen</code>. */ public void close() throws Exception { closed = true; } /** * Not supported in this base implementation. * Always throws an {@link UnsupportedOperationException}, * subclasses should override this behavior. */ public void setFactory(KeyedPoolableObjectFactory factory) throws IllegalStateException, UnsupportedOperationException { throw new UnsupportedOperationException(); } /** * Has this pool instance been closed. * @return <code>true</code> when this pool has been closed. * @since Pool 1.4 */ protected final boolean isClosed() { return closed; } /** * Throws an <code>IllegalStateException</code> when this pool has been closed. * @throws IllegalStateException when this pool has been closed. * @see #isClosed() * @since Pool 1.4 */ protected final void assertOpen() throws IllegalStateException { if (isClosed()) { throw new IllegalStateException("Pool not open"); } } private volatile boolean closed = false; }