    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017package org.apache.commons.pool2.impl;
    018
    019import java.lang.ref.SoftReference;
    020
    021/**
    022 * Extension of {@link DefaultPooledObject} to wrap pooled soft references.
    023 *
    024 * <p>This class is intended to be thread-safe.</p>
    025 *
    026 * @param <T> the type of the underlying object that the wrapped SoftReference
    027 * refers to.
    028 *
    029 * @version $Revision: $
    030 *
    031 * @since 2.0
    032 */
    033public class PooledSoftReference<T> extends DefaultPooledObject<T> {
    034
    035    /** SoftReference wrapped by this object */
    036    private volatile SoftReference<T> reference;
    037
    038    /**
    039     * Creates a new PooledSoftReference wrapping the provided reference.
    040     *
    041     * @param reference SoftReference to be managed by the pool
    042     */
    043    public PooledSoftReference(SoftReference<T> reference) {
    044        super(null);  // Null the hard reference in the parent
    045        this.reference = reference;
    046    }
    047
    048    /**
    049     * Returns the object that the wrapped SoftReference refers to.
    050     * <p>
    051     * Note that if the reference has been cleared, this method will return
    052     * null.
    053     *
    054     * @return Object referred to by the SoftReference
    055     */
    056    @Override
    057    public T getObject() {
    058        return reference.get();
    059    }
    060
    061    /**
    062     * {@inheritDoc}
    063     */
    064    @Override
    065    public String toString() {
    066        StringBuilder result = new StringBuilder();
    067        result.append("Referenced Object: ");
    068        result.append(getObject().toString());
    069        result.append(", State: ");
    070        synchronized (this) {
    071            result.append(getState().toString());
    072        }
    073        return result.toString();
    074        // TODO add other attributes
    075        // TODO encapsulate state and other attribute display in parent
    076    }
    077
    078    /**
    079     * Returns the SoftReference wrapped by this object.
    080     *
    081     * @return underlying SoftReference
    082     */
    083    public synchronized SoftReference<T> getReference() {
    084        return reference;
    085    }
    086
    087    /**
    088     * Sets the wrapped reference.
    089     *
    090     * <p>This method exists to allow a new, non-registered reference to be
    091     * held by the pool to track objects that have been checked out of the pool.
    092     * The actual parameter <strong>should</strong> be a reference to the same
    093     * object that {@link #getObject()} returns before calling this method.</p>
    094     *
    095     * @param reference new reference
    096     */
    097    public synchronized void setReference(SoftReference<T> reference) {
    098        this.reference = reference;
    099    }
    100}