ibatis.cache接口实现:RedisCache,MemcachedCache,EhcacheCache

（1）首先是Cache接口定义：

package org.apache.ibatis.cache;import java.util.concurrent.locks.ReadWriteLock;public interface Cache {  String getId();  int getSize();  void putObject(Object key, Object value);  Object getObject(Object key);  Object removeObject(Object key);  void clear();  ReadWriteLock getReadWriteLock();}

（2）RedisCache接口实现：

package cn.lsoft.undoner.dao.cache;import java.util.Set;import java.util.concurrent.locks.ReadWriteLock;import java.util.concurrent.locks.ReentrantReadWriteLock;import org.apache.commons.codec.digest.DigestUtils;import org.apache.ibatis.cache.Cache;import org.slf4j.Logger;import org.slf4j.LoggerFactory;import org.springframework.context.ApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext;import cn.lsoft.undoner.util.SerializeUtil;import redis.clients.jedis.Jedis;import redis.clients.jedis.JedisPool;import redis.clients.jedis.JedisPoolConfig;/* * 使用第三方缓存服务器，处理二级缓存 */public class RedisCache implements Cache {private static Logger logger = LoggerFactory.getLogger(RedisCache.class);/** The ReadWriteLock. */private final ReadWriteLock readWriteLock = new ReentrantReadWriteLock();private String id;private JedisPool jedisPool;private static final int DB_INDEX = 1;private final String COMMON_CACHE_KEY = "COM:";private static final String UTF8 = "utf-8";private ApplicationContext context;/** * 按照一定规则标识key */private String getKey(Object key) {StringBuilder accum = new StringBuilder();accum.append(COMMON_CACHE_KEY);accum.append(this.id).append(":");accum.append(DigestUtils.md5Hex(String.valueOf(key)));return accum.toString();}/** * redis key规则前缀 */private String getKeys() {return COMMON_CACHE_KEY + this.id + ":*";}public RedisCache() {}public RedisCache(final String id) {if (id == null) {throw new IllegalArgumentException("必须传入ID");}context = new ClassPathXmlApplicationContext("/spring/spring-db-redis-context.xml");JedisPoolConfig jedisPoolConfig = (JedisPoolConfig) context.getBean("poolConfig");jedisPool = new JedisPool(jedisPoolConfig, "23.45.6.7", 6379);logger.debug(">>>>>>>>>>>>>>>>>>>>>MybatisRedisCache:id=" + id);this.id = id;}@Overridepublic String getId() {return this.id;}@Overridepublic int getSize() {Jedis jedis = null;int result = 0;boolean borrowOrOprSuccess = true;try {jedis = jedisPool.getResource();jedis.select(DB_INDEX);Set<byte[]> keys = jedis.keys(getKeys().getBytes(UTF8));if (null != keys && !keys.isEmpty()) {result = keys.size();}logger.debug(this.id + "---->>>>总缓存数:" + result);} catch (Exception e) {borrowOrOprSuccess = false;if (jedis != null)jedisPool.returnBrokenResource(jedis);} finally {if (borrowOrOprSuccess)jedisPool.returnResource(jedis);}return result;}@Overridepublic void putObject(Object key, Object value) {Jedis jedis = null;boolean borrowOrOprSuccess = true;try {jedis = jedisPool.getResource();jedis.select(DB_INDEX);byte[] keys = getKey(key).getBytes(UTF8);jedis.set(keys, SerializeUtil.serialize(value));logger.debug("添加缓存--------" + this.id + " | " +keys.toString() + ":" + value.toString() );getSize();} catch (Exception e) {borrowOrOprSuccess = false;if (jedis != null)jedisPool.returnBrokenResource(jedis);} finally {if (borrowOrOprSuccess)jedisPool.returnResource(jedis);}}@Overridepublic Object getObject(Object key) {Jedis jedis = null;Object value = null;boolean borrowOrOprSuccess = true;try {jedis = jedisPool.getResource();jedis.select(DB_INDEX);byte[] keys = getKey(key).getBytes(UTF8);value = SerializeUtil.unserialize(jedis.get(getKey(key).getBytes(UTF8)));logger.debug("从缓存中获取-----" + this.id + " | "+keys.toString() + ":"  + value.toString());getSize();} catch (Exception e) {borrowOrOprSuccess = false;if (jedis != null)jedisPool.returnBrokenResource(jedis);} finally {if (borrowOrOprSuccess)jedisPool.returnResource(jedis);}return value;}@Overridepublic Object removeObject(Object key) {Jedis jedis = null;Object value = null;boolean borrowOrOprSuccess = true;try {jedis = jedisPool.getResource();jedis.select(DB_INDEX);byte[] keys = getKey(key).getBytes(UTF8);value = jedis.del(getKey(key).getBytes(UTF8));logger.debug("LRU算法从缓存中移除-----" + this.id + " | " +keys.toString() + ":" + value.toString());getSize();} catch (Exception e) {borrowOrOprSuccess = false;if (jedis != null)jedisPool.returnBrokenResource(jedis);} finally {if (borrowOrOprSuccess)jedisPool.returnResource(jedis);}return value;}@Overridepublic void clear() {Jedis jedis = null;boolean borrowOrOprSuccess = true;try {jedis = jedisPool.getResource();jedis.select(DB_INDEX);// 如果有删除操作，会影响到整个表中的数据，因此要清空一个mapper的缓存（一个mapper的不同数据操作对应不同的key）Set<byte[]> keys = jedis.keys(getKeys().getBytes(UTF8));logger.debug("出现CUD操作，清空对应Mapper缓存======>" + keys.size());for (byte[] key : keys) {jedis.del(key);}// 下面是网上流传的方法，极大的降低系统性能，没起到加入缓存应有的作用，这是不可取的。// jedis.flushDB();// jedis.flushAll();} catch (Exception e) {borrowOrOprSuccess = false;if (jedis != null)jedisPool.returnBrokenResource(jedis);} finally {if (borrowOrOprSuccess)jedisPool.returnResource(jedis);}}@Overridepublic ReadWriteLock getReadWriteLock() {return readWriteLock;}}

（3）MemcachedCache接口实现：

package org.mybatis.caches.memcached;import java.util.concurrent.locks.ReadWriteLock;import org.apache.ibatis.cache.Cache;/** * The Memcached-based Cache implementation. * * @author Simone Tripodi */public final class MemcachedCache implements Cache {    private static final MemcachedClientWrapper MEMCACHED_CLIENT = new MemcachedClientWrapper();    /**     * The {@link ReadWriteLock}.     */    private final ReadWriteLock readWriteLock = new DummyReadWriteLock();    /**     * The cache id.     */    private final String id;    /**     * Builds a new Memcached-based Cache.     *     * @param id the Mapper id.     */    public MemcachedCache(final String id) {        this.id = id;    }    /**     * {@inheritDoc}     */    public void clear() {        MEMCACHED_CLIENT.removeGroup(this.id);    }    /**     * {@inheritDoc}     */    public String getId() {        return this.id;    }    /**     * {@inheritDoc}     */    public Object getObject(Object key) {        return MEMCACHED_CLIENT.getObject(key);    }    /**     * {@inheritDoc}     */    public ReadWriteLock getReadWriteLock() {        return this.readWriteLock;    }    /**     * {@inheritDoc}     */    public int getSize() {        return Integer.MAX_VALUE;    }    /**     * {@inheritDoc}     */    public void putObject(Object key, Object value) {        MEMCACHED_CLIENT.putObject(key, value, this.id);    }    /**     * {@inheritDoc}     */    public Object removeObject(Object key) {        return MEMCACHED_CLIENT.removeObject(key);    }}

（3）EhcacheCache接口实现：

package org.mybatis.caches.ehcache;import java.io.IOException;import java.io.InputStream;import java.util.concurrent.locks.ReadWriteLock;import java.util.concurrent.locks.ReentrantReadWriteLock;import net.sf.ehcache.CacheManager;import net.sf.ehcache.Ehcache;import net.sf.ehcache.Element;import org.apache.ibatis.cache.Cache;import org.apache.ibatis.cache.CacheException;/** * Cache adapter for Ehcache. * * @version $Id: EhcacheCache.java 3454 2010-12-29 20:35:44Z simone.tripodi $ */public final class EhcacheCache implements Cache {    /**     * The cache manager reference.     */    private static final CacheManager CACHE_MANAGER = createCacheManager();    /**     * Looks for "/ehcache.xml" classpath resource and builds the relative     * {@code CacheManager}; if it's no found or it is impossible to load it,     * returns the default manager.     *     * @return the application cache manager.     */    private static CacheManager createCacheManager() {        CacheManager cacheManager;        InputStream input = EhcacheCache.class.getResourceAsStream("/ehcache.xml");        if (input != null) {            try {                cacheManager = CacheManager.create(input);            } catch (Throwable t) {                cacheManager = CacheManager.create();            } finally {                try {                    input.close();                } catch (IOException e) {                }            }        } else {            cacheManager = CacheManager.create();        }        return cacheManager;    }    /**     * The {@code ReadWriteLock}.     */    private final ReadWriteLock readWriteLock = new ReentrantReadWriteLock();    /**     * The cache id.     */    private final String id;    /**     *     *     * @param id     */    public EhcacheCache(final String id) {        if (id == null) {            throw new IllegalArgumentException("Cache instances require an ID");        }        this.id = id;        if (!CACHE_MANAGER.cacheExists(this.id)) {            CACHE_MANAGER.addCache(this.id);        }    }    /**     * {@inheritDoc}     */    public void clear() {        this.getCache().removeAll();    }    /**     * {@inheritDoc}     */    public String getId() {        return this.id;    }    /**     * {@inheritDoc}     */    public Object getObject(Object key) {        try {            Element cachedElement = this.getCache().get(key.hashCode());            if (cachedElement == null) {                return null;            }            return cachedElement.getObjectValue();        } catch (Throwable t) {            throw new CacheException(t);        }    }    /**     * {@inheritDoc}     */    public ReadWriteLock getReadWriteLock() {        return this.readWriteLock;    }    /**     * {@inheritDoc}     */    public int getSize() {        try {            return this.getCache().getSize();        } catch (Throwable t) {            throw new CacheException(t);        }    }    /**     * {@inheritDoc}     */    public void putObject(Object key, Object value) {        try {            this.getCache().put(new Element(key.hashCode(), value));        } catch (Throwable t) {            throw new CacheException(t);        }    }    /**     * {@inheritDoc}     */    public Object removeObject(Object key) {        try {            Object obj = this.getObject(key);            this.getCache().remove(key.hashCode());            return obj;        } catch (Throwable t) {            throw new CacheException(t);        }    }    /**     * Returns the ehcache manager for this cache.     *     * @return the ehcache manager for this cache.     */    private Ehcache getCache() {        return CACHE_MANAGER.getCache(this.id);    }    /**     * {@inheritDoc}     */    @Override    public boolean equals(Object obj) {        if (this == obj) {            return true;        }        if (obj == null) {            return false;        }        if (!(obj instanceof Cache)) {            return false;        }        Cache otherCache = (Cache) obj;        return this.id.equals(otherCache.getId());    }    /**     * {@inheritDoc}     */    @Override    public int hashCode() {        return this.id.hashCode();    }    /**     * {@inheritDoc}     */    @Override    public String toString() {        return "EHCache {"                + this.id                + "}";    }}