//$Id: Interceptor.java 7883 2005-08-12 20:03:07Z oneovthafew $
package org.hibernate;
import java.io.Serializable;
import java.util.Iterator;
import org.hibernate.type.Type;
/**
* Allows user code to inspect and/or change property values.
* <br><br>
* Inspection occurs before property values are written and after they are read
* from the database.<br>
* <br>
* There might be a single instance of <tt>Interceptor</tt> for a <tt>SessionFactory</tt>, or a new instance
* might be specified for each <tt>Session</tt>. Whichever approach is used, the interceptor must be
* serializable if the <tt>Session</tt> is to be serializable. This means that <tt>SessionFactory</tt>-scoped
* interceptors should implement <tt>readResolve()</tt>.<br>
* <br>
* The <tt>Session</tt> may not be invoked from a callback (nor may a callback cause a collection or proxy to
* be lazily initialized).<br>
* <br>
* Instead of implementing this interface directly, it is usually better to extend <tt>EmptyInterceptor</tt>
* and override only the callback methods of interest.
*
* @see SessionFactory#openSession(Interceptor)
* @see org.hibernate.cfg.Configuration#setInterceptor(Interceptor)
* @see EmptyInterceptor
* @author Gavin King
*/
public interface Interceptor {
/**
* Called just before an object is initialized. The interceptor may change the <tt>state</tt>, which will
* be propagated to the persistent object. Note that when this method is called, <tt>entity</tt> will be
* an empty uninitialized instance of the class.
*
* @return <tt>true</tt> if the user modified the <tt>state</tt> in any way.
*/
public boolean onLoad(Object entity, Serializable id, Object[] state, String[] propertyNames, Type[] types) throws CallbackException;
/**
* Called when an object is detected to be dirty, during a flush. The interceptor may modify the detected
* <tt>currentState</tt>, which will be propagated to both the database and the persistent object.
* Note that not all flushes end in actual synchronization with the database, in which case the
* new <tt>currentState</tt> will be propagated to the object, but not necessarily (immediately) to
* the database. It is strongly recommended that the interceptor <b>not</b> modify the <tt>previousState</tt>.
*
* @return <tt>true</tt> if the user modified the <tt>currentState</tt> in any way.
*/
public boolean onFlushDirty(Object entity, Serializable id, Object[] currentState, Object[] previousState, String[] propertyNames, Type[] types) throws CallbackException;
/**
* Called before an object is saved. The interceptor may modify the <tt>state</tt>, which will be used for
* the SQL <tt>INSERT</tt> and propagated to the persistent object.
*
* @return <tt>true</tt> if the user modified the <tt>state</tt> in any way.
*/
public boolean onSave(Object entity, Serializable id, Object[] state, String[] propertyNames, Type[] types) throws CallbackException;
/**
* Called before an object is deleted. It is not recommended that the interceptor modify the <tt>state</tt>.
*/
public void onDelete(Object entity, Serializable id, Object[] state, String[] propertyNames, Type[] types) throws CallbackException;
/**
* Called before a collection is (re)created.
*/
public void onCollectionRecreate(Object collection, Serializable key) throws CallbackException;
/**
* Called before a collection is deleted.
*/
public void onCollectionRemove(Object collection, Serializable key) throws CallbackException;
/**
* Called before a collection is updated.
*/
public void onCollectionUpdate(Object collection, Serializable key) throws CallbackException;
/**
* Called before a flush
*/
public void preFlush(Iterator entities) throws CallbackException;
/**
* Called after a flush that actually ends in execution of the SQL statements required to synchronize
* in-memory state with the database.
*/
public void postFlush(Iterator entities) throws CallbackException;
/**
* Called to distinguish between transient and detached entities. The return value determines the
* state of the entity with respect to the current session.
* <ul>
* <li><tt>Boolean.TRUE</tt> - the entity is transient
* <li><tt>Boolean.FALSE</tt> - the entity is detached
* <li><tt>null</tt> - Hibernate uses the <tt>unsaved-value</tt> mapping and other heuristics to
* determine if the object is unsaved
* </ul>
* @param entity a transient or detached entity
* @return Boolean or <tt>null</tt> to choose default behaviour
*/
public Boolean isTransient(Object entity);
/**
* Called from <tt>flush()</tt>. The return value determines whether the entity is updated
* <ul>
* <li>an array of property indices - the entity is dirty
* <li>an empty array - the entity is not dirty
* <li><tt>null</tt> - use Hibernate's default dirty-checking algorithm
* </ul>
* @param entity a persistent entity
* @return array of dirty property indices or <tt>null</tt> to choose default behaviour
*/
public int[] findDirty(Object entity, Serializable id, Object[] currentState, Object[] previousState, String[] propertyNames, Type[] types);
/**
* Instantiate the entity class. Return <tt>null</tt> to indicate that Hibernate should use
* the default constructor of the class. The identifier property of the returned instance
* should be initialized with the given identifier.
*
* @param entityName the name of the entity
* @param entityMode The type of entity instance to be returned.
* @param id the identifier of the new instance
* @return an instance of the class, or <tt>null</tt> to choose default behaviour
*/
public Object instantiate(String entityName, EntityMode entityMode, Serializable id) throws CallbackException;
/**
* Get the entity name for a persistent or transient instance
* @param object an entity instance
* @return the name of the entity
*/
public String getEntityName(Object object) throws CallbackException;
/**
* Get a fully loaded entity instance that is cached externally
* @param entityName the name of the entity
* @param id the instance identifier
* @return a fully initialized entity
* @throws CallbackException
*/
public Object getEntity(String entityName, Serializable id) throws CallbackException;
/**
* Called when a Hibernate transaction is begun via the Hibernate <tt>Transaction</tt>
* API. Will not be called if transactions are being controlled via some other
* mechanism (CMT, for example).
*/
public void afterTransactionBegin(Transaction tx);
/**
* Called before a transaction is committed (but not before rollback).
*/
public void beforeTransactionCompletion(Transaction tx);
/**
* Called after a transaction is committed or rolled back.
*/
public void afterTransactionCompletion(Transaction tx);
/**
* Called when sql string is being prepared.
* @param sql sql to be prepared
* @return original or modified sql
*/
public String onPrepareStatement(String sql);
}
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