oracle.toplink.essentials.internal.indirection.IndirectionPolicy Maven / Gradle / Ivy
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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);
}