基于Map多种方式实现简单的缓存处理

private static Map<String, Object>cacheMap;
    
    public staticObject getCache(String key, Object defaultValue) {
        Object obj =getCacheMap().get(key);
        //Object obj = getSession().getAttribute(key);
        return obj==null?defaultValue:obj;
    }
 
    public static voidputCache(String key, Object value) {
        getCacheMap().put(key, value);
        //getSession().setAttribute(key, value);
}
 
    public static voidremoveCache(String key) {
        getCacheMap().remove(key);
        //getSession().removeAttribute(key);
}
    
    
    public static Map<String, Object>getCacheMap() {
        if (cacheMap==null){
            cacheMap = new HashMap<String, Object>();
        }
        returncacheMap;
    }

/**
 * 使用的是LinkedHashMap实现
 */
public class LRU<K, V> extends LinkedHashMap<K, V>{

    private static final long serialVersionUID = 1L;

    //缓存大小
    private intcachaSize;

    public LRU(intcachaSize) {
        super(10, 0.75f, true);

        this.cachaSize =cachaSize;

    }

    /*** 缓存是否已满
     */@Override
    protected boolean removeEldestEntry(Map.Entry<K, V>eldest) {
        boolean r = size() >cachaSize;
        if(r) {
            System.out.println("清除缓存key：" +eldest.getKey());
        }
        returnr;

    }
}

importjava.util.concurrent.ConcurrentHashMap;

public classConcurrentHashMapTest {

    private static ConcurrentHashMap<String, String> cacheMap = new ConcurrentHashMap<>();

    /*** 获取缓存的对象
     *
     * @paramaccount
     * @return
     */
    public staticString getCache(String account) {

        account =getCacheKey(account);
        //如果缓冲中有该账号，则返回value
        if(cacheMap.containsKey(account)) {
            returncacheMap.get(account);
        }
        //如果缓存中没有该账号，把该帐号对象缓存到concurrentHashMap中
initCache(account);
        returncacheMap.get(account);
    }

    /*** 初始化缓存
     *
     * @paramaccount
     */
    private static voidinitCache(String account) {
        //一般是进行数据库查询，将查询的结果进行缓存
        cacheMap.put(account, "18013093863");
    }

    /*** 拼接一个缓存key
     *
     * @paramaccount
     * @return
     */
    private staticString getCacheKey(String account) {
        return Thread.currentThread().getId() + "-" +account;
    }

    /*** 移除缓存信息
     *
     * @paramaccount
     */
    public static voidremoveCache(String account) {
        cacheMap.remove(getCacheKey(account));
    }

}