iBATIS中使用EHCache

需要实现CacheController接口并通过一系列的配置委托iBATIS使用EHCache进行缓存.

package com.ibatis.sqlmap.engine.cache.EhCacheController;
import java.net.URL;
import java.util.Properties;
import net.sf.ehcache.Cache;
import net.sf.ehcache.CacheManager;
import net.sf.ehcache.Element;
import com.ibatis.sqlmap.engine.cache.CacheController;
import com.ibatis.sqlmap.engine.cache.CacheModel;
/**
* EhCache Implementation of the {@link com.ibatis.sqlmap.engine.cache.CacheController} interface to be able to use
* EhCache as a cache implementation in iBatis. You can configure your cache model as follows, by example, in your
* sqlMapping files:
* <cacheModel id="myCache" type="nl.rabobank.springproject.ibatis.EhCacheController" readOnly="true" serialize="false">
*    <property name="configFile" value="/path-to-ehcache.xml"/>
* </cacheModel>
* Alternatively, you can use a type alias in your type attribute and defining the class with a
* <TypeAlias> declaration, see iBatis documentation on how to do this.
*/
public class EhCacheController implements CacheController {
    /** The EhCache CacheManager. */
    private CacheManager cacheManager;
    /**
      * Flush a cache model.
      * @param cacheModel - the model to flush.
      */
    public void flush(CacheModel cacheModel) {
         getCache(cacheModel).removeAll();
     }
    /**
      * Get an object from a cache model.
      * @param cacheModel - the model.
      * @param key         - the key to the object.
      * @return the object if in the cache, or null(?).
      */
    public Object getObject(CacheModel cacheModel, Object key) {
         Object result = null;
         Element element = getCache(cacheModel).get(key);
        if (element != null) {
             result = element.getObjectValue();
         }
        return result;
     }
    /**
      * Put an object into a cache model.
      * @param cacheModel - the model to add the object to.
      * @param key         - the key to the object.
      * @param object      - the object to add.
      */
    public void putObject(CacheModel cacheModel, Object key, Object object) {
         getCache(cacheModel).put(new Element(key, object));
     }
    /**
      * Remove an object from a cache model.
      * @param cacheModel - the model to remove the object from.
      * @param key         - the key to the object.
      * @return the removed object(?).
      */
    public Object removeObject(CacheModel cacheModel, Object key) {
         Object result = this.getObject(cacheModel, key);
         getCache(cacheModel).remove(key);
        return result;
     }
    /**
      * Configure a cache controller. Initialize the EH Cache Manager as a singleton.
      * @param props - the properties object continaing configuration information.
      */
    public void setProperties(Properties props) {
         URL url = getClass().getResource(props.getProperty("configFile"));
         cacheManager = CacheManager.create(url);
     }
    /**
      * Gets an EH Cache based on an iBatis cache Model.
      * @param cacheModel - the cache model.
      * @return the EH Cache.
      */
    private Cache getCache(CacheModel cacheModel) {
         String cacheName = cacheModel.getId();
         Cache cache = cacheManager.getCache(cacheName);
        return cache;
     }
    /**
      * Shut down the EH Cache CacheManager.
      */
    public void finalize() {
        if (cacheManager != null) {
             cacheManager.shutdown();
         }
     }
}

package com.ibatis.sqlmap.engine.cache.EhCacheController;import java.net.URL;import java.util.Properties;import net.sf.ehcache.Cache;import net.sf.ehcache.CacheManager;import net.sf.ehcache.Element;import com.ibatis.sqlmap.engine.cache.CacheController;import com.ibatis.sqlmap.engine.cache.CacheModel;/** * EhCache Implementation of the {@link com.ibatis.sqlmap.engine.cache.CacheController} interface to be able to use * EhCache as a cache implementation in iBatis. You can configure your cache model as follows, by example, in your * sqlMapping files: * <cacheModel id="myCache" type="nl.rabobank.springproject.ibatis.EhCacheController" readOnly="true" serialize="false"> *   <property name="configFile" value="/path-to-ehcache.xml"/> * </cacheModel> * Alternatively, you can use a type alias in your type attribute and defining the class with a * <TypeAlias> declaration, see iBatis documentation on how to do this. */public class EhCacheController implements CacheController {    /** The EhCache CacheManager. */    private CacheManager cacheManager;    /**     * Flush a cache model.     * @param cacheModel - the model to flush.     */    public void flush(CacheModel cacheModel) {        getCache(cacheModel).removeAll();    }    /**     * Get an object from a cache model.     * @param cacheModel - the model.     * @param key        - the key to the object.     * @return the object if in the cache, or null(?).     */    public Object getObject(CacheModel cacheModel, Object key) {        Object result = null;        Element element = getCache(cacheModel).get(key);        if (element != null) {            result = element.getObjectValue();        }        return result;    }    /**     * Put an object into a cache model.     * @param cacheModel - the model to add the object to.     * @param key        - the key to the object.     * @param object     - the object to add.     */    public void putObject(CacheModel cacheModel, Object key, Object object) {        getCache(cacheModel).put(new Element(key, object));    }    /**     * Remove an object from a cache model.     * @param cacheModel - the model to remove the object from.     * @param key        - the key to the object.     * @return the removed object(?).     */    public Object removeObject(CacheModel cacheModel, Object key) {        Object result = this.getObject(cacheModel, key);        getCache(cacheModel).remove(key);        return result;    }    /**     * Configure a cache controller. Initialize the EH Cache Manager as a singleton.     * @param props - the properties object continaing configuration information.     */    public void setProperties(Properties props) {        URL url = getClass().getResource(props.getProperty("configFile"));        cacheManager = CacheManager.create(url);    }    /**     * Gets an EH Cache based on an iBatis cache Model.     * @param cacheModel - the cache model.     * @return the EH Cache.     */    private Cache getCache(CacheModel cacheModel) {        String cacheName = cacheModel.getId();        Cache cache = cacheManager.getCache(cacheName);        return cache;    }    /**     * Shut down the EH Cache CacheManager.     */    public void finalize() {        if (cacheManager != null) {            cacheManager.shutdown();        }    }}

接下来一个sql Mapping config的例子

<!--sp-->xml version="1.0" encoding="UTF-8" ?>

     PUBLIC "-//ibatis.apache.org//DTD SQL Map 2.0//EN"
     "http://ibatis.apache.org/dtd/sql-map-2.dtd">
<sqlMap namespace="myNamespace">
  <!-- Use type aliases to avoid typing the full classname every time. -->
  <typeAlias alias="MyPojo" type="nl.myproject.MyPojo"/>
  <typeAlias alias="MapCacheController" type="com.ibatis.sqlmap.engine.cache.EhCacheController"/>
  <cacheModel id="MyPojoCache" type="MapCacheController" readOnly="true" serialize="false">
    <property name="configFile" value="/ehcache.xml"/>
  cacheModel>
  <resultMap id="ResultQueryMap" class="MyPojo">
     ...property mappings go here...
  resultMap>
  <select id="getMyPojoList" resultMap="ResultQueryMap" cacheModel="MyPojoCache">
     ...select query to get your pojo from the database goes here...
  select>
sqlMap>

<!--l version="1.0" encoding="UTF-8"-->  <!-- Use type aliases to avoid typing the full classname every time. -->          

        ...property mappings go here...        ...select query to get your pojo from the database goes here...  

一个eh-cache.xml配置示例

<ehcache>
   ...put your default cache here...
  <cache
    name="myNamespace.MyPojoCache"
    maxElementsInMemory="5"
    eternal="false"
    timeToLiveSeconds="60"
    overflowToDisk="false"
    memoryStoreEvictionPolicy="LRU"/>
ehcache>

  ...put your default cache here...  

需要留意的是:

1.节点配置在sqlMap.xml中,需要放在classpath下.

2.你可以在sqlMap.xml中添加多个同时指向一个.如果CacheManager是单例模式,那么这将减少很多不必要的配置,但是这只是一个初级的问题.

3.必须设置sqlMapConfig.xml中节点中的cacheModelsEnabled=true,否则缓存不会被启用