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.

1. package com.ibatis.sqlmap.engine.cache.EhCacheController;
2. import java.net.URL;
3. import java.util.Properties;
4. import net.sf.ehcache.Cache;
5. import net.sf.ehcache.CacheManager;
6. import net.sf.ehcache.Element;
7. import com.ibatis.sqlmap.engine.cache.CacheController;
8. import com.ibatis.sqlmap.engine.cache.CacheModel;
9. /**
10. * EhCache Implementation of the {@link com.ibatis.sqlmap.engine.cache.CacheController} interface to be able to use
11. * EhCache as a cache implementation in iBatis. You can configure your cache model as follows, by example, in your
12. * sqlMapping files:
13. * <cacheModel id="myCache" type="nl.rabobank.springproject.ibatis.EhCacheController" readOnly="true" serialize="false">
14. *    <property name="configFile" value="/path-to-ehcache.xml"/>
15. * </cacheModel>
16. * Alternatively, you can use a type alias in your type attribute and defining the class with a
17. * <TypeAlias> declaration, see iBatis documentation on how to do this.
18. */
19. public class EhCacheController implements CacheController {
20.     /** The EhCache CacheManager. */
21.     private CacheManager cacheManager;
22.     /**
23.       * Flush a cache model.
24.       * @param cacheModel - the model to flush.
25.       */
26.     public void flush(CacheModel cacheModel) {
27.          getCache(cacheModel).removeAll();
28.      }
29.     /**
30.       * Get an object from a cache model.
31.       * @param cacheModel - the model.
32.       * @param key         - the key to the object.
33.       * @return the object if in the cache, or null(?).
34.       */
35.     public Object getObject(CacheModel cacheModel, Object key) {
36.          Object result = null;
37.          Element element = getCache(cacheModel).get(key);
38.         if (element != null) {
39.              result = element.getObjectValue();
40.          }
41.         return result;
42.      }
43.     /**
44.       * Put an object into a cache model.
45.       * @param cacheModel - the model to add the object to.
46.       * @param key         - the key to the object.
47.       * @param object      - the object to add.
48.       */
49.     public void putObject(CacheModel cacheModel, Object key, Object object) {
50.          getCache(cacheModel).put(new Element(key, object));
51.      }
52.     /**
53.       * Remove an object from a cache model.
54.       * @param cacheModel - the model to remove the object from.
55.       * @param key         - the key to the object.
56.       * @return the removed object(?).
57.       */
58.     public Object removeObject(CacheModel cacheModel, Object key) {
59.          Object result = this.getObject(cacheModel, key);
60.          getCache(cacheModel).remove(key);
61.         return result;
62.      }
63.     /**
64.       * Configure a cache controller. Initialize the EH Cache Manager as a singleton.
65.       * @param props - the properties object continaing configuration information.
66.       */
67.     public void setProperties(Properties props) {
68.          URL url = getClass().getResource(props.getProperty("configFile"));
69.          cacheManager = CacheManager.create(url);
70.      }
71.     /**
72.       * Gets an EH Cache based on an iBatis cache Model.
73.       * @param cacheModel - the cache model.
74.       * @return the EH Cache.
75.       */
76.     private Cache getCache(CacheModel cacheModel) {
77.          String cacheName = cacheModel.getId();
78.          Cache cache = cacheManager.getCache(cacheName);
79.         return cache;
80.      }
81.     /**
82.       * Shut down the EH Cache CacheManager.
83.       */
84.     public void finalize() {
85.         if (cacheManager != null) {
86.              cacheManager.shutdown();
87.          }
88.      }
89. }

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

1. <!--sp-->xml version="1.0" encoding="UTF-8" ?>
3.      PUBLIC "-//ibatis.apache.org//DTD SQL Map 2.0//EN"
4.      "http://ibatis.apache.org/dtd/sql-map-2.dtd">
5. <sqlMap namespace="myNamespace">
6.   <!-- Use type aliases to avoid typing the full classname every time. -->
7.   <typeAlias alias="MyPojo" type="nl.myproject.MyPojo"/>
8.   <typeAlias alias="MapCacheController" type="com.ibatis.sqlmap.engine.cache.EhCacheController"/>
9.   <cacheModel id="MyPojoCache" type="MapCacheController" readOnly="true" serialize="false">
10.     <property name="configFile" value="/ehcache.xml"/>
11.   cacheModel>
12.   <resultMap id="ResultQueryMap" class="MyPojo">
13.      ...property mappings go here...
14.   resultMap>
15.   <select id="getMyPojoList" resultMap="ResultQueryMap" cacheModel="MyPojoCache">
16.      ...select query to get your pojo from the database goes here...
17.   select>
18. 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

1. <ehcache>
2.    ...put your default cache here...
3.   <cache
4.     name="myNamespace.MyPojoCache"
5.     maxElementsInMemory="5"
6.     eternal="false"
7.     timeToLiveSeconds="60"
8.     overflowToDisk="false"
9.     memoryStoreEvictionPolicy="LRU"/>
10. 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