| /* |
| * 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. |
| */ |
| /* |
| * $Id: ObjectPool.java 475981 2006-11-16 23:35:53Z minchau $ |
| */ |
| package org.apache.xml.utils; |
| |
| import java.util.ArrayList; |
| |
| import org.apache.xml.res.XMLErrorResources; |
| import org.apache.xml.res.XMLMessages; |
| |
| |
| /** |
| * Pool of object of a given type to pick from to help memory usage |
| * @xsl.usage internal |
| */ |
| public class ObjectPool implements java.io.Serializable |
| { |
| static final long serialVersionUID = -8519013691660936643L; |
| |
| /** Type of objects in this pool. |
| * @serial */ |
| private final Class objectType; |
| |
| /** Stack of given objects this points to. |
| * @serial */ |
| private final ArrayList freeStack; |
| |
| /** |
| * Constructor ObjectPool |
| * |
| * @param type Type of objects for this pool |
| */ |
| public ObjectPool(Class type) |
| { |
| objectType = type; |
| freeStack = new ArrayList(); |
| } |
| |
| /** |
| * Constructor ObjectPool |
| * |
| * @param className Fully qualified name of the type of objects for this pool. |
| */ |
| public ObjectPool(String className) |
| { |
| try |
| { |
| objectType = ObjectFactory.findProviderClass( |
| className, ObjectFactory.findClassLoader(), true); |
| } |
| catch(ClassNotFoundException cnfe) |
| { |
| throw new WrappedRuntimeException(cnfe); |
| } |
| freeStack = new ArrayList(); |
| } |
| |
| |
| /** |
| * Constructor ObjectPool |
| * |
| * |
| * @param type Type of objects for this pool |
| * @param size Size of vector to allocate |
| */ |
| public ObjectPool(Class type, int size) |
| { |
| objectType = type; |
| freeStack = new ArrayList(size); |
| } |
| |
| /** |
| * Constructor ObjectPool |
| * |
| */ |
| public ObjectPool() |
| { |
| objectType = null; |
| freeStack = new ArrayList(); |
| } |
| |
| /** |
| * Get an instance of the given object in this pool if available |
| * |
| * |
| * @return an instance of the given object if available or null |
| */ |
| public synchronized Object getInstanceIfFree() |
| { |
| |
| // Check if the pool is empty. |
| if (!freeStack.isEmpty()) |
| { |
| |
| // Remove object from end of free pool. |
| Object result = freeStack.remove(freeStack.size() - 1); |
| return result; |
| } |
| |
| return null; |
| } |
| |
| /** |
| * Get an instance of the given object in this pool |
| * |
| * |
| * @return An instance of the given object |
| */ |
| public synchronized Object getInstance() |
| { |
| |
| // Check if the pool is empty. |
| if (freeStack.isEmpty()) |
| { |
| |
| // Create a new object if so. |
| try |
| { |
| return objectType.newInstance(); |
| } |
| catch (InstantiationException ex){} |
| catch (IllegalAccessException ex){} |
| |
| // Throw unchecked exception for error in pool configuration. |
| throw new RuntimeException(XMLMessages.createXMLMessage(XMLErrorResources.ER_EXCEPTION_CREATING_POOL, null)); //"exception creating new instance for pool"); |
| } |
| else |
| { |
| |
| // Remove object from end of free pool. |
| Object result = freeStack.remove(freeStack.size() - 1); |
| |
| return result; |
| } |
| } |
| |
| /** |
| * Add an instance of the given object to the pool |
| * |
| * |
| * @param obj Object to add. |
| */ |
| public synchronized void freeInstance(Object obj) |
| { |
| |
| // Make sure the object is of the correct type. |
| // Remove safety. -sb |
| // if (objectType.isInstance(obj)) |
| // { |
| freeStack.add(obj); |
| // } |
| // else |
| // { |
| // throw new IllegalArgumentException("argument type invalid for pool"); |
| // } |
| } |
| } |