java 缓存jcs:

有时候我们需要频繁的访问数据库获得某些数据，这样大大的增加了访问数据库方面的开销，降低了系统的性能。

一 解决办法：

将数据放进缓存中。

二 适用条件：

1 需要经常使用

2 数据不经常更新

三 需要导入jar包：

jcs-1.3.jar

四 流程向导：

五 代码演示：

package jcsCache;import java.io.Serializable;
import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import java.util.ListIterator;import org.apache.jcs.JCS;
import org.apache.jcs.access.exception.CacheException;
import org.apache.jcs.admin.CacheElementInfo;
import org.apache.jcs.admin.CacheRegionInfo;
import org.apache.jcs.admin.JCSAdminBean;
import org.apache.jcs.engine.control.CompositeCache;/**** cache jcs 练习* <功能详细描述>** @version  [版本号, 2014-2-7]* @see  [相关类/方法]* @since  [产品/模块版本]*/
public class CacheUtil implements Serializable
{private static final long serialVersionUID = 1L;/*** 获取cache* <功能详细描述>* @param cacheName* @return JCS* @see [类、类#方法、类#成员]*/public static JCS getCache(String cacheName){JCS cache = null;try{cache = JCS.getInstance(cacheName);}catch (CacheException e){e.printStackTrace();}return cache;}/*** 获取cache 中key对应的value* <功能详细描述>* @param cacheName* @param key* @return Object* @see [类、类#方法、类#成员]*/public static Object getObject(String cacheName, Object key){Object obj = null;JCS cache = getCache(cacheName);if (null != cache){obj = cache.get(key);}if (null == obj){//obj = DatabaseManager.getByKey(key);obj = "from data base";}return obj;}/***  将对象放进缓存* <功能详细描述>* @param cacheName* @param key* @param value* @return　boolean* @see [类、类#方法、类#成员]*/public static boolean putObject(String cacheName, Object key, Object value){JCS cache = getCache(cacheName);boolean result = false;if (null != cache){try{cache.put(key, value);result = true;}catch (CacheException e){e.printStackTrace();}}return result;}/*** 清除所有缓存* <功能详细描述>* @param cacheName* @return* @see [类、类#方法、类#成员]*/public static boolean cleanAll(String cacheName){JCS cache = getCache(cacheName);boolean result = false;if (null != cache){try{cache.clear();result = true;}catch (CacheException e){e.printStackTrace();}}return result;}/*** 根据key清除对应的缓存* <功能详细描述>* @param cacheName* @param key* @return* @see [类、类#方法、类#成员]*/public static boolean cleanByKey(String cacheName, Object key){JCS cache = getCache(cacheName);boolean result = false;if (null != cache){try{cache.remove(key);result = true;}catch (CacheException e){e.printStackTrace();}}return result;}/*** 获取某个缓存的元数据* <功能详细描述>* @param cacheName* @return CacheElementInfo* @see [类、类#方法、类#成员]*/public static CacheElementInfo getMetadataByCacheName(String cacheName){JCSAdminBean admin = new JCSAdminBean();CacheElementInfo info = null;LinkedList<?> linkedList = null;try{linkedList = admin.buildElementInfo(cacheName);ListIterator<?> iterator = linkedList.listIterator();while (iterator.hasNext()){info = (CacheElementInfo)iterator.next();}}catch (Exception e){e.printStackTrace();}return info;}/*** 获取缓存元数据* <功能详细描述>* @return* @see [类、类#方法、类#成员]*/public static List<CompositeCache> getMetadata(){JCSAdminBean admin = new JCSAdminBean();LinkedList<?> linkedList = null;CacheRegionInfo info = null;CompositeCache compCache = null;List<CompositeCache> list = new ArrayList<CompositeCache>();try{linkedList = admin.buildCacheInfo();ListIterator<?> iterator = linkedList.listIterator();while (iterator.hasNext()){info = (CacheRegionInfo)iterator.next();compCache = info.getCache();list.add(compCache);}}catch (Exception e){e.printStackTrace();}return list;}
}