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Java动态缓存技术:WEB缓存应用

五月 18, 2008 by admin  
类别:JAVA开发

抢个沙发先

可以实现不等待，线程自动更新缓存

java动态缓jar包http://dl2.csdn.net/down4/20070918/18203740920.jar

源代码：

?View Code JAVA
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package com.cari.web.cache;
 
/** *//**
 * @author zsy
 *
 */
public class CacheData ...{
    private Object data;
    private long time;
    private int count;
 
    public CacheData() ...{
 
    }
 
    public CacheData(Object data, long time, int count) ...{
        this.data = data;
        this.time = time;
        this.count = count;
    }
 
    public CacheData(Object data) ...{
        this.data = data;
        this.time = System.currentTimeMillis();
        this.count = 1;
    }
 
    public void addCount() ...{
        count++;
    }
 
    public int getCount() ...{
        return count;
    }
    public void setCount(int count) ...{
        this.count = count;
    }
    public Object getData() ...{
        return data;
    }
    public void setData(Object data) ...{
        this.data = data;
    }
    public long getTime() ...{
        return time;
    }
    public void setTime(long time) ...{
        this.time = time;
    }
}

CacheOperation.java 缓存处理类:

?View Code JAVA
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package com.cari.web.cache;
 
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Hashtable;
 
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
 
/** *//**
 * @author zsy
 */
public class CacheOperation ...{
    private static final Log log = LogFactory.getLog(CacheOperation.class);
    private static CacheOperation singleton = null;
 
    private Hashtable cacheMap;//存放缓存数据
 
    private ArrayList threadKeys;//处于线程更新中的key值列表
 
    public static CacheOperation getInstance() ...{
        if (singleton == null) ...{
            singleton = new CacheOperation();
        }
        return singleton;
    }
 
    private CacheOperation() ...{
        cacheMap = new Hashtable();
        threadKeys = new ArrayList();
    }
 
    /** *//**
     * 添加数据缓存
     * 与方法getCacheData(String key, long intervalTime, int maxVisitCount)配合使用
     * @param key
     * @param data
     */
    public void addCacheData(String key, Object data) ...{
        addCacheData(key, data, true);
    }
 
    private void addCacheData(String key, Object data, boolean check) ...{
        if (Runtime.getRuntime().freeMemory() < 5L*1024L*1024L) ...{//虚拟机内存小于10兆，则清除缓存
            log.warn("WEB缓存：内存不足，开始清空缓存！");
            removeAllCacheData();
            return;
        } else if(check && cacheMap.containsKey(key)) ...{
            log.warn("WEB缓存：key值= " + key + " 在缓存中重复, 本次不缓存！");
            return;
        }
        cacheMap.put(key, new CacheData(data));
    }
 
    /** *//**
     * 取得缓存中的数据
     * 与方法addCacheData(String key, Object data)配合使用
     * @param key
     * @param intervalTime 缓存的时间周期，小于等于0时不限制
     * @param maxVisitCount 访问累积次数，小于等于0时不限制
     * @return
     */
    public Object getCacheData(String key, long intervalTime, int maxVisitCount) ...{
        CacheData cacheData = (CacheData)cacheMap.get(key);
        if (cacheData == null) ...{
            return null;
        }
        if (intervalTime > 0 && (System.currentTimeMillis() - cacheData.getTime()) > intervalTime) ...{
            removeCacheData(key);
            return null;
        }
        if (maxVisitCount > 0 && (maxVisitCount - cacheData.getCount()) <= 0) ...{
            removeCacheData(key);
            return null;
        } else ...{
            cacheData.addCount();
        }
        return cacheData.getData();
    }

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