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 * glassfish/bootstrap/legal/CDDLv1.0.txt or 
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// Copyright (c) 1998, 2007, Oracle. All rights reserved.  
package oracle.toplink.essentials.internal.indirection;

import java.io.*;
import java.util.*;
import oracle.toplink.essentials.exceptions.*;
import oracle.toplink.essentials.internal.descriptors.*;
import oracle.toplink.essentials.internal.sessions.MergeManager;
import oracle.toplink.essentials.mappings.*;
import oracle.toplink.essentials.queryframework.*;
import oracle.toplink.essentials.internal.sessions.AbstractRecord;
import oracle.toplink.essentials.internal.sessions.UnitOfWorkImpl;
import oracle.toplink.essentials.internal.sessions.AbstractSession;

/**
 * 

Purpose

: * An IndirectionPolicy acts as a 'rules' holder that determines * the behavior of a ForeignReferenceMapping (or TransformationMapping) * with respect to indirection, or lack thereof. *

*

Description

: * IndirectionPolicy is an abstract class that defines the protocol to be implemented by * subclasses so that the assorted DatabaseMappings can use an assortment of * indirection policies:
    *
  • no indirection policy (read everything from database) *
  • basic indirection policy (use ValueHolders) *
  • transparent indirection policy (collections only) *
  • proxy indirection policy (transparent 1:1 indirection using JDK 1.3's Proxy) *
* *

*

Responsibilities

: *
    *
  • instantiate the various IndirectionPolicies *
*

* * @see ForeignReferenceMapping * @author Mike Norman * @since TOPLink/Java 2.5 */ public abstract class IndirectionPolicy implements Cloneable, Serializable { protected DatabaseMapping mapping; /** * INTERNAL: * Construct a new indirection policy. */ public IndirectionPolicy() { super(); } /** * INTERNAL: * Return a backup clone of the attribute. */ public Object backupCloneAttribute(Object attributeValue, Object clone, Object backup, UnitOfWorkImpl unitOfWork) { return this.getMapping().buildBackupCloneForPartObject(attributeValue, clone, backup, unitOfWork); } /** * INTERNAL * Return true if the refresh shoud refresh on this mapping or not. */ protected ReadObjectQuery buildCascadeQuery(MergeManager mergeManager) { ReadObjectQuery cascadeQuery = new ReadObjectQuery(); if (mergeManager.shouldCascadeAllParts()) { cascadeQuery.cascadeAllParts(); cascadeQuery.refreshIdentityMapResult(); } if (mergeManager.shouldCascadePrivateParts() && getForeignReferenceMapping().isPrivateOwned()) { cascadeQuery.cascadePrivateParts(); cascadeQuery.refreshIdentityMapResult(); } return cascadeQuery; } /** * INTERNAL: * Clones itself. */ public Object clone() { try { return super.clone(); } catch (CloneNotSupportedException e) { throw new InternalError(); } } /** * INTERNAL: * Return a clone of the attribute. * @param builtDirectlyFromRow indicates that we are building the clone * directly from a row as opposed to building the original from the * row, putting it in the shared cache, and then cloning the original. */ public abstract Object cloneAttribute(Object attributeValue, Object original, Object clone, UnitOfWorkImpl unitOfWork, boolean buildDirectlyFromRow); /** * INTERNAL: * Return the primary key for the reference object (i.e. the object * object referenced by domainObject and specified by mapping). * This key will be used by a RemoteValueHolder. */ public Vector extractPrimaryKeyForReferenceObject(Object referenceObject, AbstractSession session) { return this.getOneToOneMapping().extractPrimaryKeysFromRealReferenceObject(referenceObject, session); } /** * INTERNAL: * Return the reference row for the reference object. * This allows the new row to be built without instantiating * the reference object. * Return null if the object has already been instantiated. */ public abstract AbstractRecord extractReferenceRow(Object referenceObject); /** * INTERNAL: * Reduce casting clutter.... */ protected CollectionMapping getCollectionMapping() { return (CollectionMapping)this.getMapping(); } /** * INTERNAL: * Reduce casting clutter.... */ protected ForeignReferenceMapping getForeignReferenceMapping() { return (ForeignReferenceMapping)this.getMapping(); } /** * INTERNAL: * Return the database mapping that uses the indirection policy. */ public DatabaseMapping getMapping() { return mapping; } /** * INTERNAL: * Reduce casting clutter.... */ protected ObjectReferenceMapping getOneToOneMapping() { return (ObjectReferenceMapping)this.getMapping(); } /** * INTERNAL: * Return the original indirection object for a unit of work indirection object. */ public abstract Object getOriginalIndirectionObject(Object unitOfWorkIndirectionObject, AbstractSession session); /** * INTERNAL: * Return the "real" attribute value, as opposed to any wrapper. * This will trigger the wrapper to instantiate the value. */ public abstract Object getRealAttributeValueFromObject(Object object, Object attribute); /** * INTERNAL: * Given a proxy object, trigger the indirection and return the actual object represented by the proxy. * For non-proxy indirection, this method will simply return the object. */ public static Object getValueFromProxy(Object value) { return value; } /** * INTERNAL: * Initialize the indirection policy (Do nothing by default) */ public void initialize() { } /** * INTERNAL: * Iterate over the specified attribute value, * heeding the settings in the iterator. */ public void iterateOnAttributeValue(DescriptorIterator iterator, Object attributeValue) { if (attributeValue != null) { this.getMapping().iterateOnRealAttributeValue(iterator, attributeValue); } } /** * INTERNAL: * Return the null value of the appropriate attribute. That is, the * field from the database is NULL, return what should be * placed in the object's attribute as a result. */ public abstract Object nullValueFromRow(); /** * INTERNAL: * Return whether the specified object is instantiated. */ public abstract boolean objectIsInstantiated(Object object); /** * INTERNAL: * set the database mapping that uses the indirection policy. */ public void setMapping(DatabaseMapping mapping) { this.mapping = mapping; } /** * INTERNAL: * Set the value of the appropriate attribute of target to attributeValue. * In this case, simply place the value inside the target. */ public void setRealAttributeValueInObject(Object target, Object attributeValue) { this.getMapping().setAttributeValueInObject(target, attributeValue); } /** * INTERNAL: * Return whether the indirection policy actually uses indirection. * The default is true. */ public boolean usesIndirection() { return true; } /** * INTERNAL: * Return whether the indirection policy uses transparent indirection. * The default is false. */ public boolean usesTransparentIndirection(){ return false; } /** * INTERNAL: * Verify that the value of the attribute within an instantiated object * is of the appropriate type for the indirection policy. * If it is incorrect, throw an exception. * If the value is null return a new indirection object to be used for the attribute. */ public Object validateAttributeOfInstantiatedObject(Object attributeValue) throws DescriptorException { return attributeValue; } /** * INTERNAL: * Verify that the container policy is compatible with the * indirection policy. If it is incorrect, add an exception to the * integrity checker. */ public void validateContainerPolicy(IntegrityChecker checker) throws DescriptorException { // by default, do nothing } /** * INTERNAL: * Verify that attributeType is correct for the * indirection policy. If it is incorrect, add an exception to the * integrity checker. */ public void validateDeclaredAttributeType(Class attributeType, IntegrityChecker checker) throws DescriptorException { // by default, do nothing } /** * INTERNAL: * Verify that attributeType is an appropriate collection type for the * indirection policy. If it is incorrect, add an exception to the integrity checker. */ public void validateDeclaredAttributeTypeForCollection(Class attributeType, IntegrityChecker checker) throws DescriptorException { // by default, do nothing } /** * INTERNAL: * Verify that getter returnType is correct for the * indirection policy. If it is incorrect, add an exception * to the integrity checker. */ public void validateGetMethodReturnType(Class returnType, IntegrityChecker checker) throws DescriptorException { // by default, do nothing } /** * INTERNAL: * Verify that getter returnType is an appropriate collection type for the * indirection policy. If it is incorrect, add an exception to the integrity checker. */ public void validateGetMethodReturnTypeForCollection(Class returnType, IntegrityChecker checker) throws DescriptorException { // by default, do nothing } /** * INTERNAL: * Verify that setter parameterType is correct for the * indirection policy. If it is incorrect, add an exception * to the integrity checker. */ public void validateSetMethodParameterType(Class parameterType, IntegrityChecker checker) throws DescriptorException { // by default, do nothing } /** * INTERNAL: * Verify that setter parameterType is an appropriate collection type for the * indirection policy. If it is incorrect, add an exception to the integrity checker. */ public void validateSetMethodParameterTypeForCollection(Class parameterType, IntegrityChecker checker) throws DescriptorException { // by default, do nothing } /** * INTERNAL: * Return the value to be stored in the object's attribute. * This value is determined by the query. */ public abstract Object valueFromQuery(ReadQuery query, AbstractRecord row, AbstractSession session); /** * INTERNAL: * Return the value to be stored in the object's attribute. * This value is determined by the row. */ public abstract Object valueFromRow(Object object); }





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