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The jBATIS persistence framework will help you to significantly reduce the amount of Java code that you normally need to access a relational database. iBATIS simply maps JavaBeans to SQL statements using a very simple XML descriptor.

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/*
 *  Copyright 2004 Clinton Begin
 *
 *  Licensed 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 com.ibatis.sqlmap.engine.cache.fifo;

import java.util.Collections;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Properties;

import com.ibatis.sqlmap.engine.cache.CacheController;
import com.ibatis.sqlmap.engine.cache.CacheModel;

/**
 * FIFO (first in, first out) cache controller implementation
 */
public class FifoCacheController implements CacheController {

    private int cacheSize;
    private Map cache;
    private List keyList;

    /**
     * Default constructor
     */
    public FifoCacheController() {
        this.cacheSize = 100;
        this.cache = Collections.synchronizedMap(new HashMap());
        this.keyList = Collections.synchronizedList(new LinkedList());
    }

    public int getCacheSize() {
        return cacheSize;
    }

    public void setCacheSize(int cacheSize) {
        this.cacheSize = cacheSize;
    }

    /**
     * Configures the cache
     *
     * @param props
     *            Optionally can contain properties [reference-type=WEAK|SOFT|STRONG]
     */
    @Override
    public void setProperties(CacheModel cacheModel, Properties props) {
        String size = props.getProperty("cache-size");
        if (size == null) {
            size = props.getProperty("size");
        }
        if (size != null) {
            cacheSize = Integer.parseInt(size);
        }
    }

    /**
     * Add an object to the cache
     *
     * @param cacheModel
     *            The cacheModel
     * @param key
     *            The key of the object to be cached
     * @param value
     *            The object to be cached
     */
    @Override
    public void putObject(CacheModel cacheModel, Object key, Object value) {
        cache.put(key, value);
        keyList.add(key);
        if (keyList.size() > cacheSize) {
            try {
                Object oldestKey = keyList.remove(0);
                cache.remove(oldestKey);
            } catch (IndexOutOfBoundsException e) {
                // ignore
            }
        }
    }

    /**
     * Get an object out of the cache.
     *
     * @param cacheModel
     *            The cache model
     * @param key
     *            The key of the object to be returned
     * @return The cached object (or null)
     */
    @Override
    public Object getObject(CacheModel cacheModel, Object key) {
        return cache.get(key);
    }

    @Override
    public Object removeObject(CacheModel cacheModel, Object key) {
        keyList.remove(key);
        return cache.remove(key);
    }

    /**
     * Flushes the cache.
     *
     * @param cacheModel
     *            The cache model
     */
    @Override
    public void flush(CacheModel cacheModel) {
        cache.clear();
        keyList.clear();
    }

}
    

    

    

            

    

            



    
    






    
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