Map项目中的实例

package com.power7000.service.impl.sun.sts;

import java.util.concurrent.ConcurrentHashMap;

import org.apache.log4j.Logger;
public class PowerDataMonthlyMap {
    private static Logger logger = Logger.getLogger(PowerDataMonthlyMap.class);

    private PowerDataMonthlyMap(){}

    private static PowerDataMonthlyMap powerDataMonthlyMap;

    public static PowerDataMonthlyMap getInstance()
    {
        if(powerDataMonthlyMap == null)
        {
            powerDataMonthlyMap = new PowerDataMonthlyMap();
        }
        return powerDataMonthlyMap;
    }
private final ConcurrentHashMap powerDataMonthlymap = new ConcurrentHashMap();

    public TimeTagCombinedActive get(String key) {
        if (this.checkExist(key)) {
            return powerDataMonthlymap.get(key);
        }
        return null;
    }
public void remove(String key) {
        try {
            powerDataMonthlymap.remove(key);
        } catch (NullPointerException e) {
            logger.error(e);
        }
    }

    public void add(String key, TimeTagCombinedActive timeTagCombinedActive) {
        if (key == null || timeTagCombinedActive == null) {
            return;
        }
        try {
            powerDataMonthlymap.put(key, timeTagCombinedActive);
        } catch (NullPointerException e) {
            logger.error(e);
        }
    }
public boolean checkExist(String key) {
        try {
            return powerDataMonthlymap.containsKey(key);
        } catch (NullPointerException e) {
            // 写入日志
            logger.error(e);
            return false;
        }
    }

    /**
     * session
     * @return
     */
    public ConcurrentHashMap getSessionMap(){
        return powerDataMonthlymap;
    }
}