背景
这是我的工作（简化）GenericDao接口，由任何实现DomainDao:
通用Dao.java
@NoRepositoryBean
public interface GenericDao<E extends Persistable<K>, K extends Serializable> extends JpaRepository<E, K> {
public List<E> findAll();
public E persist(E entity);
}
通用DaoImpl.java
public class GenericDaoImpl<E extends Persistable<K>, K extends Serializable> extends SimpleJpaRepository<E, K> implements GenericDao<E, K> {
private final JpaEntityInformation<E, ?> entityInformation;
private final EntityManager em;
private final Class<E> type;
public GenericDaoImpl(JpaEntityInformation<E, ?> entityInformation, EntityManager em) {
super(entityInformation, em);
this.entityInformation = entityInformation;
this.em = em;
this.type = entityInformation.getJavaType();
}
@Override
public List<E> findAll() {
return super.findAll();
}
@Override
@Transactional
public E persist(E entity) {
if (entityInformation.isNew(entity) || !EntityUtils.isPrimaryKeyGenerated(type) && !em.contains(entity)) {
em.persist(entity);
}
return entity;
}
}
例如，管理域Foo and Bar，您只需要创建两个接口，如下所示：
FooDao.java
public interface FooDao extends GenericDao<Foo, Integer> {
}
BarDao.java
public interface BarDao extends GenericDao<Bar, Integer> {
}
The @Autowired http://static.springsource.org/spring/docs/3.1.x/javadoc-api/org/springframework/beans/factory/annotation/Autowired.html的注释Spring会自动实例化一个GenericDaoImpl具有良好的实体和主键类型。
Problem
我现在尝试使用 EhCache 和EhCache Spring 注解 http://code.google.com/p/ehcache-spring-annotations/ model.
通用Dao.java
@NoRepositoryBean
public interface GenericDao<E extends Persistable<K>, K extends Serializable> extends JpaRepository<E, K> {
@Cacheable(cacheName = "dao")
public List<E> findAll();
@TriggersRemove(cacheName = "dao")
public E persist(E entity);
}
应用程序上下文.xml
<ehcache:annotation-driven cache-manager="ehCacheManager" />
<bean id="ehCacheManager" class="org.springframework.cache.ehcache.EhCacheManagerFactoryBean" />
ehcache.xml
<cache name="dao"
eternal="false"
maxElementsInMemory="10000"
overflowToDisk="false"
timeToIdleSeconds="86400"
timeToLiveSeconds="86400"
memoryStoreEvictionPolicy="LFU" />
使用的问题GenericDao，是缓存应该管理每个DomainDao彼此独立。例如，使用当前配置，如果我调用fooDao.findAll()， 进而barDao.persist(new Bar())，生成的缓存fooDao.findAll()将被重置，因为将使用相同的缓存（即<cache name="dao" />），虽然不应该。
Trails
我尝试实现自己的CacheKeyGenerator http://code.google.com/p/ehcache-spring-annotations/wiki/CacheKeyGenerators，这将考虑调用的类型DomainDao:
应用程序上下文.xml
<ehcache:annotation-driven cache-manager="ehCacheManager" default-cache-key-generator="daoCacheKeyGenerator" />
<bean id="ehCacheManager" class="org.springframework.cache.ehcache.EhCacheManagerFactoryBean" />
<bean id="daoCacheKeyGenerator" class="myapp.dao.support.DaoCacheKeyGenerator" />
DaoCacheKeyGenerator.java
public class DaoCacheKeyGenerator implements CacheKeyGenerator<DaoCacheKey> {
@Override
public DaoCacheKey generateKey(MethodInvocation methodInvocation) {
Class<?> clazz = methodInvocation.getThis().getClass().getInterfaces()[0];
Method method = methodInvocation.getMethod();
String methodName = method.getName();
Class<?>[] parameterClasses = method.getParameterTypes();
return new DaoCacheKey(clazz, methodName, parameterClasses);
}
@Override
public DaoCacheKey generateKey(Object... data) {
return null;
}
}
DaoCacheKey.java
public class DaoCacheKey implements Serializable {
private static final long serialVersionUID = 338466521373614710L;
private Class<?> clazz;
private String methodName;
private Class<?>[] parameterClasses;
public DaoCacheKey(Class<?> clazz, String methodName, Class<?>[] parameterClasses) {
this.clazz = clazz;
this.methodName = methodName;
this.parameterClasses = parameterClasses;
}
@Override
public boolean equals(Object obj) { // <-- breakpoint
if (obj instanceof DaoCacheKey) {
DaoCacheKey other = (DaoCacheKey) obj;
if (clazz.equals(other.clazz)) {
// if @TriggersRemove, reset any cache generated by a find* method of the same DomainDao
boolean removeCache = !methodName.startsWith("find") && other.methodName.startsWith("find");
// if @Cacheable, check if the result has been previously cached
boolean getOrCreateCache = methodName.equals(other.methodName) && Arrays.deepEquals(parameterClasses, other.parameterClasses);
return removeCache || getOrCreateCache;
}
}
return false;
}
@Override
public int hashCode() { // <-- breakpoint
return super.hashCode();
}
}
上面的问题DaoCacheKey，是那个equals方法 get 从未被调用（程序至少不会中断），但是hashCode一个这样做，所以该算法无法应用。
Question
有人已经管理过这样的缓存吗？如果是的话怎么办？我的尝试是否相关？如果是，如何制作equals调用的方法，而不是hashCode一？通过扩展现有的CacheKeyGenerator http://code.google.com/p/ehcache-spring-annotations/wiki/CacheKeyGenerators？如果有，是哪一个？
