PersistenceManager (JDO JavaDoc)

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javax.jdo
Interface PersistenceManager

public interface PersistenceManager

PersistenceManager is the primary interface for JDO-aware application components. It is the factory for Query and Transaction instances, and contains methods to manage the life cycle of PersistenceCapable instances.

A PersistenceManager is obtained from the PersistenceManagerFactory (recommended) or by construction.

Version:: 0.9
Author:: Craig Russell

Method Summary

void close()
          Close this PersistenceManager so that no further requests may be made on it.

Transaction currentTransaction()
          Return the Transaction instance associated with a PersistenceManager.

void deletePersistent(java.lang.Object pc)
          Delete the persistent instance from the data store.

void deletePersistentAll(java.util.Collection pcs)
          Delete a Collection of instances from the data store.

void deletePersistentAll(java.lang.Object[] pcs)
          Delete an array of instances from the data store.

void evict(java.lang.Object pc)
          Mark an instance as no longer needed in the cache.

void evictAll()
          Mark all persistent-nontransactional instances as no longer needed in the cache.

void evictAll(java.util.Collection pcs)
          Mark a Collection of instances as no longer needed in the cache.

void evictAll(java.lang.Object[] pcs)
          Mark an array of instances as no longer needed in the cache.

Extent getExtent(java.lang.Class persistenceCapableClass, boolean subclasses)
          The PersistenceManager manages a collection of instances in the data store based on the class of the instances.

boolean getIgnoreCache()
          Get the ignoreCache setting for queries.

boolean getMultithreaded()
          Get the current Multithreaded flag for this PersistenceManager.

java.lang.Object getObjectById(java.lang.Object oid, boolean validate)
          This method locates a persistent instance in the cache of instances managed by this PersistenceManager.

java.lang.Object getObjectId(java.lang.Object pc)
          The ObjectId returned by this method represents the JDO identity of the instance.

java.lang.Class getObjectIdClass(java.lang.Class cls)
          Return the Class that implements the JDO Identity for the specified PersistenceCapable class.

PersistenceManagerFactory getPersistenceManagerFactory()
          This method returns the PersistenceManagerFactory used to create this PersistenceManager.

java.lang.Object getTransactionalObjectId(java.lang.Object pc)
          The ObjectId returned by this method represents the JDO identity of the instance.

java.lang.Object getUserObject()
          The application can manage the PersistenceManager instances more easily by having an application object associated with each PersistenceManager instance.

boolean isClosed()
          A PersistenceManager instance can be used until it is closed.

void makeNontransactional(java.lang.Object pc)
          Make an instance non-transactional after commit.

void makeNontransactionalAll(java.util.Collection pcs)
          Make a Collection of instances non-transactional after commit.

void makeNontransactionalAll(java.lang.Object[] pcs)
          Make an array of instances non-transactional after commit.

void makePersistent(java.lang.Object pc)
          Make the transient instance persistent in this PersistenceManager.

void makePersistentAll(java.util.Collection pcs)
          Make a Collection of instances persistent.

void makePersistentAll(java.lang.Object[] pcs)
          Make an array of instances persistent.

void makeTransactional(java.lang.Object pc)
          Make an instance subject to transactional boundaries.

void makeTransactionalAll(java.util.Collection pcs)
          Make a Collection of instances subject to transactional boundaries.

void makeTransactionalAll(java.lang.Object[] pcs)
          Make an array of instances subject to transactional boundaries.

void makeTransient(java.lang.Object pc)
          Make an instance transient, removing it from management by this PersistenceManager.

void makeTransientAll(java.util.Collection pcs)
          Make a Collection of instances transient, removing them from management by this PersistenceManager.

void makeTransientAll(java.lang.Object[] pcs)
          Make an array of instances transient, removing them from management by this PersistenceManager.

java.lang.Object newObjectIdInstance(java.lang.Class pcClass, java.lang.String str)
          This method returns an object id instance corresponding to the Class and String arguments.

Query newQuery()
          Create a new Query with no elements.

Query newQuery(java.lang.Class cls)
          Create a new Query specifying the Class of the candidate instances.

Query newQuery(java.lang.Class cls, java.util.Collection cln)
          Create a new Query with the candidate Class and Collection.

Query newQuery(java.lang.Class cls, java.util.Collection cln, java.lang.String filter)
          Create a new Query with the Class of the candidate instances, candidate Collection, and filter.

Query newQuery(java.lang.Class cls, java.lang.String filter)
          Create a new Query with the Class of the candidate instances and filter.

Query newQuery(Extent cln)
          Create a new Query with the Class of the candidate instances and candidate Extent.

Query newQuery(Extent cln, java.lang.String filter)
          Create a new Query with the candidate Extent and filter; the class is taken from the Extent.

Query newQuery(java.lang.Object compiled)
          Create a new Query using elements from another Query.

Query newQuery(java.lang.String language, java.lang.Object query)
          Create a new Query using the specified language.

void refresh(java.lang.Object pc)
          Refresh the state of the instance from the data store.

void refreshAll()
          Refresh the state of all applicable instances from the data store.

void refreshAll(java.util.Collection pcs)
          Refresh the state of a Collection of instances from the data store.

void refreshAll(java.lang.Object[] pcs)
          Refresh the state of an array of instances from the data store.

void retrieve(java.lang.Object pc)
          Retrieve field values of an instance from the store.

void retrieveAll(java.util.Collection pcs)
          Retrieve field values of instances from the store.

void retrieveAll(java.util.Collection pcs, boolean DFGOnly)
          Retrieve field values of instances from the store.

void retrieveAll(java.lang.Object[] pcs)
          Retrieve field values of instances from the store.

void retrieveAll(java.lang.Object[] pcs, boolean DFGOnly)
          Retrieve field values of instances from the store.

void setIgnoreCache(boolean flag)
          Set the ignoreCache parameter for queries.

void setMultithreaded(boolean flag)
          Set the Multithreaded flag for this PersistenceManager.

void setUserObject(java.lang.Object o)
          The application can manage the PersistenceManager instances more easily by having an application object associated with each PersistenceManager instance.

Method Detail

isClosed

public boolean isClosed()

A PersistenceManager instance can be used until it is closed.

Returns:: true if this PersistenceManager has been closed.
See Also:: close()

close

public void close()

Close this PersistenceManager so that no further requests may be made on it. A PersistenceManager instance can be used only until it is closed.

Closing a PersistenceManager might release it to the pool of available PersistenceManagers, or might be garbage collected, at the option of the JDO implementation. Before being used again to satisfy a getPersistenceManager() request, the default values for options will be restored to their values as specified in the PersistenceManagerFactory.

This method closes the PersistenceManager.

currentTransaction

public Transaction currentTransaction()

Return the Transaction instance associated with a PersistenceManager. There is one Transaction instance associated with each PersistenceManager instance. The Transaction instance supports options as well as transaction completion requests.

Returns:: the Transaction associated with this PersistenceManager.

evict

public void evict(java.lang.Object pc)

Mark an instance as no longer needed in the cache. Eviction is normally done automatically by the PersistenceManager at transaction completion. This method allows the application to explicitly provide a hint to the PersistenceManager that the instance is no longer needed in the cache.

Parameters:: pc - the instance to evict from the cache.

evictAll

public void evictAll(java.lang.Object[] pcs)

Mark an array of instances as no longer needed in the cache.

Parameters:: pcs - the array of instances to evict from the cache.
See Also:: evict(Object pc)

evictAll

public void evictAll(java.util.Collection pcs)

Mark a Collection of instances as no longer needed in the cache.

Parameters:: pcs - the Collection of instances to evict from the cache.
See Also:: evict(Object pc)

evictAll

public void evictAll()

Mark all persistent-nontransactional instances as no longer needed in the cache. It transitions all persistent-nontransactional instances to hollow. Transactional instances are subject to eviction based on the RetainValues setting.

See Also:: evict(Object pc)

refresh

public void refresh(java.lang.Object pc)

Refresh the state of the instance from the data store.

In an optimistic transaction, the state of instances in the cache might not match the state in the data store. This method is used to reload the state of the instance from the data store so that a subsequent commit is more likely to succeed.

Outside a transaction, this method will refresh nontransactional state.

Parameters:: pc - the instance to refresh.

refreshAll

public void refreshAll(java.lang.Object[] pcs)

Refresh the state of an array of instances from the data store.

Parameters:: pcs - the array of instances to refresh.
See Also:: refresh(Object pc)

refreshAll

public void refreshAll(java.util.Collection pcs)

Refresh the state of a Collection of instances from the data store.

Parameters:: pcs - the Collection of instances to refresh.
See Also:: refresh(Object pc)

refreshAll

public void refreshAll()

Refresh the state of all applicable instances from the data store.

If called with an active transaction, all transactional instances will be refreshed. If called outside an active transaction, all nontransactional instances will be refreshed.

See Also:: refresh(Object pc)

newQuery

public Query newQuery()

Create a new Query with no elements.

Returns:: the new Query.

newQuery

public Query newQuery(java.lang.Object compiled)

Create a new Query using elements from another Query. The other Query must have been created by the same JDO implementation. It might be active in a different PersistenceManager or might have been serialized and restored.

All of the settings of the other Query are copied to this Query, except for the candidate Collection or Extent.

Parameters:: compiled - another Query from the same JDO implementation
Returns:: the new Query

newQuery

public Query newQuery(java.lang.String language,
                      java.lang.Object query)

Create a new Query using the specified language.

Parameters:: language - the language of the query parameter; query - the query, which is of a form determined by the language
Returns:: the new Query

newQuery

public Query newQuery(java.lang.Class cls)

Create a new Query specifying the Class of the candidate instances.

Parameters:: cls - the Class of the candidate instances
Returns:: the new Query

newQuery

public Query newQuery(Extent cln)

Create a new Query with the Class of the candidate instances and candidate Extent.

Parameters:: cln - the Extent of candidate instances
Returns:: the new Query

newQuery

public Query newQuery(java.lang.Class cls,
                      java.util.Collection cln)

Create a new Query with the candidate Class and Collection.

Parameters:: cls - the Class of results; cln - the Collection of candidate instances
Returns:: the new Query

newQuery

public Query newQuery(java.lang.Class cls,
                      java.lang.String filter)

Create a new Query with the Class of the candidate instances and filter.

Parameters:: cls - the Class of results; filter - the filter for candidate instances
Returns:: the new Query

newQuery

public Query newQuery(java.lang.Class cls,
                      java.util.Collection cln,
                      java.lang.String filter)

Create a new Query with the Class of the candidate instances, candidate Collection, and filter.

Parameters:: cls - the Class of candidate instances; cln - the Collection of candidate instances; filter - the filter for candidate instances
Returns:: the new Query

newQuery

public Query newQuery(Extent cln,
                      java.lang.String filter)

Create a new Query with the candidate Extent and filter; the class is taken from the Extent.

Parameters:: cln - the Extent of candidate instances; filter - the filter for candidate instances
Returns:: the new Query

getExtent

public Extent getExtent(java.lang.Class persistenceCapableClass,
                        boolean subclasses)

The PersistenceManager manages a collection of instances in the data store based on the class of the instances. This method returns an Extent of instances in the data store that might be iterated or given to a Query. The Extent itself might not reference any instances, but only hold the class name and an indicator as to whether subclasses are included in the Extent.

Note that the Extent might be very large.

Parameters:: persistenceCapableClass - Class of instances; subclasses - whether to include instances of subclasses
Returns:: an Extent of the specified Class
See Also:: Query

getObjectById

public java.lang.Object getObjectById(java.lang.Object oid,
                                      boolean validate)

This method locates a persistent instance in the cache of instances managed by this PersistenceManager. The getObjectById method attempts to find an instance in the cache with the specified JDO identity. The oid parameter object might have been returned by an earlier call to getObjectId or getTransactionalObjectId, or might have been constructed by the application.

If the PersistenceManager is unable to resolve the oid parameter to an ObjectId instance, then it throws a JDOUserException.

If the validate flag is false, and there is already an instance in the cache with the same JDO identity as the oid parameter, then this method returns it. There is no change made to the state of the returned instance.

If there is not an instance already in the cache with the same JDO identity as the oid parameter, then this method creates an instance with the specified JDO identity and returns it. If there is no transaction in progress, the returned instance will be hollow or persistent-nontransactional, at the choice of the implementation.

If there is a transaction in progress, the returned instance will be hollow, persistent-nontransactional, or persistent-clean, at the choice of the implementation.

It is an implementation decision whether to access the data store, if required to determine the exact class. This will be the case of inheritance, where multiple PersistenceCapable classes share the same ObjectId class.

If the validate flag is false, and the instance does not exist in the data store, then this method might not fail. It is an implementation choice whether to fail immediately with a JDODataStoreException. But a subsequent access of the fields of the instance will throw a JDODataStoreException if the instance does not exist at that time. Further, if a relationship is established to this instance, then the transaction in which the association was made will fail.

If the validate flag is true, and there is already a transactional instance in the cache with the same JDO identity as the oid parameter, then this method returns it. There is no change made to the state of the returned instance.

If there is an instance already in the cache with the same JDO identity as the oid parameter, but the instance is not transactional, then it must be verified in the data store. If the instance does not exist in the datastore, then a JDODataStoreException is thrown.

If there is not an instance already in the cache with the same JDO identity as the oid parameter, then this method creates an instance with the specified JDO identity, verifies that it exists in the data store, and returns it. If there is no transaction in progress, the returned instance will be hollow or persistent-nontransactional, at the choice of the implementation.

If there is a data store transaction in progress, the returned instance will be persistent-clean. If there is an optimistic transaction in progress, the returned instance will be persistent-nontransactional.

Parameters:: oid - an ObjectId; validate - if the existence of the instance is to be validated
Returns:: the PersistenceCapable instance with the specified ObjectId
See Also:: getObjectId(Object pc), getTransactionalObjectId(Object pc)

getObjectId

public java.lang.Object getObjectId(java.lang.Object pc)

The ObjectId returned by this method represents the JDO identity of the instance. The ObjectId is a copy (clone) of the internal state of the instance, and changing it does not affect the JDO identity of the instance.

The getObjectId method returns an ObjectId instance that represents the object identity of the specified JDO instance. The identity is guaranteed to be unique only in the context of the JDO PersistenceManager that created the identity, and only for two types of JDO Identity: those that are managed by the application, and those that are managed by the data store.

If the object identity is being changed in the transaction, by the application modifying one or more of the application key fields, then this method returns the identity as of the beginning of the transaction. The value returned by getObjectId will be different following afterCompletion processing for successful transactions.

Within a transaction, the ObjectId returned will compare equal to the ObjectId returned by only one among all JDO instances associated with the PersistenceManager regardless of the type of ObjectId.

The ObjectId does not necessarily contain any internal state of the instance, nor is it necessarily an instance of the class used to manage identity internally. Therefore, if the application makes a change to the ObjectId instance returned by this method, there is no effect on the instance from which the ObjectId was obtained.

The getObjectById method can be used between instances of PersistenceManager of different JDO vendors only for instances of persistence capable classes using application-managed (primary key) JDO identity. If it is used for instances of classes using datastore identity, the method might succeed, but there are no guarantees that the parameter and return instances are related in any way.

Parameters:: pc - the PersistenceCapable instance
Returns:: the ObjectId of the instance
See Also:: getTransactionalObjectId(Object pc), getObjectById(Object oid, boolean validate)

getTransactionalObjectId

public java.lang.Object getTransactionalObjectId(java.lang.Object pc)

If the object identity is being changed in the transaction, by the application modifying one or more of the application key fields, then this method returns the current identity in the transaction.

If there is no transaction in progress, or if none of the key fields is being modified, then this method will return the same value as getObjectId.

Parameters:: pc - a PersistenceCapable instance
Returns:: the ObjectId of the instance
See Also:: getObjectId(Object pc), getObjectById(Object oid, boolean validate)

newObjectIdInstance

public java.lang.Object newObjectIdInstance(java.lang.Class pcClass,
                                            java.lang.String str)

This method returns an object id instance corresponding to the Class and String arguments. The String argument might have been the result of executing toString on an object id instance.

Parameters:: pcClass - the Class of the persistence-capable instance; str - the String form of the object id
Returns:: an instance of the object identity class

makePersistent

public void makePersistent(java.lang.Object pc)

Make the transient instance persistent in this PersistenceManager. This method must be called in an active transaction. The PersistenceManager assigns an ObjectId to the instance and transitions it to persistent-new. The instance will be managed in the Extent associated with its Class. The instance will be put into the data store at commit. The closure of instances of PersistenceCapable classes reachable from persistent fields will be made persistent at commit. [This is known as persistence by reachability.]

Parameters:: pc - a transient instance of a Class that implements PersistenceCapable

makePersistentAll

public void makePersistentAll(java.lang.Object[] pcs)

Make an array of instances persistent.

Parameters:: pcs - an array of transient instances
See Also:: makePersistent(Object pc)

makePersistentAll

public void makePersistentAll(java.util.Collection pcs)

Make a Collection of instances persistent.

Parameters:: pcs - a Collection of transient instances
See Also:: makePersistent(Object pc)

deletePersistent

public void deletePersistent(java.lang.Object pc)

Delete the persistent instance from the data store. This method must be called in an active transaction. The data store object will be removed at commit. Unlike makePersistent, which makes the closure of the instance persistent, the closure of the instance is not deleted from the data store. This method has no effect if the instance is already deleted in the current transaction. This method throws JDOUserException if the instance is transient or is managed by another PersistenceManager.

Parameters:: pc - a persistent instance

deletePersistentAll

public void deletePersistentAll(java.lang.Object[] pcs)

Delete an array of instances from the data store.

Parameters:: pcs - a Collection of persistent instances
See Also:: deletePersistent(Object pc)

deletePersistentAll

public void deletePersistentAll(java.util.Collection pcs)

Delete a Collection of instances from the data store.

Parameters:: pcs - a Collection of persistent instances
See Also:: deletePersistent(Object pc)

makeTransient

public void makeTransient(java.lang.Object pc)

Make an instance transient, removing it from management by this PersistenceManager.

The instance loses its JDO identity and it is no longer associated with any PersistenceManager. The state of fields is preserved unchanged.

Parameters:: pc - the instance to make transient.

makeTransientAll

public void makeTransientAll(java.lang.Object[] pcs)

Make an array of instances transient, removing them from management by this PersistenceManager.

The instances lose their JDO identity and they are no longer associated with any PersistenceManager. The state of fields is preserved unchanged.

Parameters:: pcs - the instances to make transient.

makeTransientAll

public void makeTransientAll(java.util.Collection pcs)

Make a Collection of instances transient, removing them from management by this PersistenceManager.

The instances lose their JDO identity and they are no longer associated with any PersistenceManager. The state of fields is preserved unchanged.

Parameters:: pcs - the instances to make transient.

makeTransactional

public void makeTransactional(java.lang.Object pc)

Make an instance subject to transactional boundaries.

Transient instances normally do not observe transaction boundaries. This method makes transient instances sensitive to transaction completion. If an instance is modified in a transaction, and the transaction rolls back, the state of the instance is restored to the state before the first change in the transaction.

For persistent instances read in optimistic transactions, this method allows the application to make the state of the instance part of the transactional state. At transaction commit, the state of the instance in the cache is compared to the state of the instance in the data store. If they are not the same, then an exception is thrown.

Parameters:: pc - the instance to make transactional.

makeTransactionalAll

public void makeTransactionalAll(java.lang.Object[] pcs)

Make an array of instances subject to transactional boundaries.

Parameters:: pcs - the array of instances to make transactional.
See Also:: makeTransactional(Object pc)

makeTransactionalAll

public void makeTransactionalAll(java.util.Collection pcs)

Make a Collection of instances subject to transactional boundaries.

Parameters:: pcs - the Collection of instances to make transactional.
See Also:: makeTransactional(Object pc)

makeNontransactional

public void makeNontransactional(java.lang.Object pc)

Make an instance non-transactional after commit.

Normally, at transaction completion, instances are evicted from the cache. This method allows an application to identify an instance as not being evicted from the cache at transaction completion. Instead, the instance remains in the cache with nontransactional state.

Parameters:: pc - the instance to make nontransactional.

makeNontransactionalAll

public void makeNontransactionalAll(java.lang.Object[] pcs)

Make an array of instances non-transactional after commit.

Parameters:: pcs - the array of instances to make nontransactional.
See Also:: makeNontransactional(Object pc)

makeNontransactionalAll

public void makeNontransactionalAll(java.util.Collection pcs)

Make a Collection of instances non-transactional after commit.

Parameters:: pcs - the Collection of instances to make nontransactional.
See Also:: makeNontransactional(Object pc)

retrieve

public void retrieve(java.lang.Object pc)

Retrieve field values of an instance from the store. This tells the PersistenceManager that the application intends to use the instance, and its field values must be retrieved.