oscache使用经历

　　oscache作为一款老的本地缓存，应用场景主要有页面缓存和对象缓存。这里拿在maven项目中使用oscache作为对象缓存举例说明下用法：

　　1、导入jar包

        <dependency>
            <groupId>opensymphony</groupId>
            <artifactId>oscache</artifactId>
            <version>2.4.1</version>
        </dependency>

　　2、在resources目录下新增配置文件oscache.properties

# CACHE IN MEMORY
#
# If you want to disable memory caching, just uncomment this line.
#
cache.memory=true

# CACHE SIZE
#
# Default cache size in number of items. If a size is specified but not
# an algorithm, the cache algorithm used will be LRUCache.
#
cache.capacity=100000

# CACHE LISTENERS
#
# These hook OSCache events and perform various actions such as logging
# cache hits and misses, or broadcasting to other cache instances across a cluster.
# See the documentation for further information.
#

#                      com.opensymphony.oscache.extra.CacheEntryEventListenerImpl


# CACHE ALGORITHM
#
# Default cache algorithm to use. Note that in order to use an algorithm
# the cache size must also be specified. If the cache size is not specified,
# the cache algorithm will be Unlimited cache.
#
 #cache.algorithm=com.opensymphony.oscache.base.algorithm.LRUCache
 cache.algorithm=com.opensymphony.oscache.base.algorithm.FIFOCache

# THREAD BLOCKING BEHAVIOR
#
# When a request is made for a stale cache entry, it is possible that another thread is already
# in the process of rebuilding that entry. This setting specifies how OSCache handles the
# subsequent 'non-building' threads. The default behaviour (cache.blocking=false) is to serve
# the old content to subsequent threads until the cache entry has been updated. This provides
# the best performance (at the cost of serving slightly stale data). When blocking is enabled,
# threads will instead block until the new cache entry is ready to be served. Once the new entry
# is put in the cache the blocked threads will be restarted and given the new entry.
# Note that even if blocking is disabled, when there is no stale data available to be served
# threads will block until the data is added to the cache by the thread that is responsible
# for building the data.
#
# cache.blocking=false

# JAVAGROUPS CLUSTER PROPERTIES
#
# Configuration properites for the JavaGroups clustering. Only one of these
# should be specified. Default values (as shown below) will be used if niether
# property is set. See the clustering documentation and the JavaGroups project
# (www.javagroups.com) for more information on these settings.
#
#cache.cluster.properties=UDP(singleton_name=screenWidthAdapter;tos=8;mcast_addr=225.90.21.10;mcast_port=50103;mcast_send_buf_size=640K;mcast_recv_buf_size=25M;ip_ttl=32;loopback=true;discard_incompatible_packets=true;enable_bundling=true;max_bundle_size=64K;max_bundle_timeout=30;enable_diagnostics=true;thread_naming_pattern=book;timer.num_threads=4;thread_pool.enabled=true;thread_pool.min_threads=2;thread_pool.max_threads=8;thread_pool.keep_alive_time=5000;thread_pool.queue_enabled=true;thread_pool.queue_max_size=10000;thread_pool.rejection_policy=discard;oob_thread_pool.enabled=true;oob_thread_pool.min_threads=1;oob_thread_pool.max_threads=8;oob_thread_pool.keep_alive_time=5000;oob_thread_pool.queue_enabled=false;oob_thread_pool.queue_max_size=100;oob_thread_pool.rejection_policy=Run):PING(timeout=2000;num_initial_members=3):MERGE2(min_interval=10000;max_interval=30000):FD(timeout=20000;max_tries=9):FD_SOCK():FD_ALL():VERIFY_SUSPECT(timeout=15000):BARRIER():pbcast.NAKACK(retransmit_timeout=300,600,1200,2400,4800,9600,19200;use_mcast_xmit=true;use_stats_for_retransmission=true;xmit_history_max_size=500;max_rebroadcast_timeout=20000;discard_delivered_msgs=false;gc_lag=500;use_stats_for_retransmission=false;exponential_backoff=0):UNICAST(timeout=300,600,1200,2400,4800,9600,19200):pbcast.STABLE(stability_delay=1000;desired_avg_gossip=20000;max_bytes=1M):pbcast.GMS(join_timeout=3000;print_local_addr=true;view_bundling=true):FC(max_credits=500K;min_threshold=0.20;ignore_synchronous_response=true):FRAG2(frag_size=60K):pbcast.STATE_TRANSFER()

　　3、新增缓存类

package com.inspur.chinanet.point.cache;

import java.math.BigDecimal;
import java.util.Date;
import java.util.concurrent.atomic.AtomicLong;
import java.util.logging.Logger;

import com.opensymphony.oscache.base.NeedsRefreshException;
import com.opensymphony.oscache.general.GeneralCacheAdministrator;
import com.opensymphony.oscache.web.filter.ExpiresRefreshPolicy;

/**
 * 本地缓存
 *
 * @author wulinfeng
 * @version C10 2018年3月28日
 * @since SDP V300R003C10
 */
public class OsCache extends GeneralCacheAdministrator
{
    
    private static final Logger LOG = Logger.getLogger("OsCache");
    
    /**
     * 序列化ID
     */
    private static final long serialVersionUID = -3814537980571610987L;
    
    // 缓存命中次数
    private AtomicLong hitCount = new AtomicLong(0L);
    
    // 总请求次数
    private AtomicLong reqCount = new AtomicLong(0L);
    
    // 命中率
    private double hitRate = 0D;
    
    private static final OsCache cache = new OsCache();
    
    /**
     * 单例
     */
    public static OsCache getInstance()
    {
        return cache;
    }
    
    /**
     * 从OSCACHE中获取原始缓存数据
     * 
     * @param key 缓存KEY值
     * @param refreshTime 失效时间，-1时为永久缓存
     * @return 原始缓存数据
     */
    public Object get(String key, int refreshTime)
    {
        reqCount.incrementAndGet();
        Object obj = null;
        try
        {
            obj = this.getFromCache(key, refreshTime);
            hitCount.incrementAndGet();
        }
        catch (NeedsRefreshException e)
        {
            this.cancelUpdate(key);
            LOG.warning(e.getMessage());
        }
        return obj;
    }
    
    /**
     * 从OSCACHE中获取原始缓存数据
     * 
     * @param key 缓存KEY值
     * @param value Object 内容对象
     * @param refreshTime 失效时间，-1时为永久缓存
     * @return 原始缓存数据
     */
    public void put(String key, Object value, int refreshTime)
    {
        if (refreshTime == -1)
        {
            this.putInCache(key, value);
        }
        else
        {
            this.putInCache(key, value, new ExpiresRefreshPolicy(refreshTime));
        }
    }
    
    /**
     * 从OSCACHE中删除缓存数据
     * 
     * @param key 缓存KEY值
     */
    public void remove(String key)
    {
        this.removeEntry(key);
    }
    
    /**
     * 从OSCACHE中删除所有缓存数据
     * 
     * @param date 预定删除时间
     */
    public void removeAll(Date date)
    {
        if (date == null)
        {
            this.flushAll();
        }
        else
        {
            this.flushAll(date);
        }
    }
    
    /**
     * 获取命中率
     *
     * @author wulinfeng
     * @return
     */
    public double getHitRate()
    {
        if (reqCount.longValue() == 0L)
        {
            return 0;
        }
        
        hitRate = (double)hitCount.longValue() / reqCount.longValue();
        BigDecimal bd = new BigDecimal(hitRate);
        bd = bd.setScale(2, BigDecimal.ROUND_HALF_UP);
        
        return bd.doubleValue();
    }
}

　　4、使用缓存主方法

　　 public static void main(String[] args)
    {
        User user = (User)OsCache.getInstance().get("user_", -1);
        
        if(user != null)
        {
            LOG.info(user.toString());
        }
        else
        {
            LOG.info("no user.");
            user = new User();
            user.setName("wulinfeng");
            user.setAge(34);
            user.setSex(1);
            OsCache.getInstance().put("user_", user, -1);
            user = (User)OsCache.getInstance().get("user_", -1);
            LOG.info(user.toString());
        }

　　5、执行主方法结果

三月 28, 2018 9:12:48 下午 com.opensymphony.oscache.base.Config loadProperties
信息: OSCache: Getting properties from URL file:/E:/workspace/TeaPot/target/classes/oscache.properties for the default configuration
三月 28, 2018 9:12:48 下午 com.opensymphony.oscache.base.Config loadProperties
信息: OSCache: Properties read {cache.algorithm=com.opensymphony.oscache.base.algorithm.FIFOCache, cache.capacity=100000, cache.memory=true}
三月 28, 2018 9:12:48 下午 com.opensymphony.oscache.general.GeneralCacheAdministrator <init>
信息: Constructed GeneralCacheAdministrator()
三月 28, 2018 9:12:48 下午 com.opensymphony.oscache.general.GeneralCacheAdministrator createCache
信息: Creating new cache
三月 28, 2018 9:12:48 下午 com.inspur.chinanet.point.cache.OsCache get
警告: null
三月 28, 2018 9:12:48 下午 com.inspur.chinanet.point.App main
信息: no user.
三月 28, 2018 9:12:48 下午 com.inspur.chinanet.point.App main
信息: User [name=wulinfeng, sex=1, age=34]