com.sleepycat.persist.PrimaryIndex<PK,E>
|
Berkeley DB version 4.8.30 |
|||||||||
| PREV CLASS NEXT CLASS | FRAMES NO FRAMES | |||||||||
| SUMMARY: NESTED | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD | |||||||||
java.lang.Object
public class PrimaryIndex<PK,E>
The primary index for an entity class and its primary key.
PrimaryIndex objects are thread-safe. Multiple threads may
safely call the methods of a shared PrimaryIndex object.
PrimaryIndex implements EntityIndex to map the primary
key type (PK) to the entity type (E).
The Entity annotation may be used to define an entity class and
the PrimaryKey annotation may be used to define a primary key as
shown in the following example.
@Entity
class Employee {
@PrimaryKey
long id;
String name;
Employee(long id, String name) {
this.id = id;
this.name = name;
}
private Employee() {} // For bindings
}
To obtain the PrimaryIndex for a given entity class, call EntityStore.getPrimaryIndex, passing the
primary key class and the entity class. For example:
EntityStore store = new EntityStore(...);
PrimaryIndex<Long,Employee> primaryIndex =
store.getPrimaryIndex(Long.class, Employee.class);
Note that Long.class is passed as the primary key class, but the
primary key field has the primitive type long. When a primitive
primary key field is used, the corresponding primitive wrapper class is used
to access the primary index. For more information on key field types, see
PrimaryKey.
The PrimaryIndex provides the primary storage and access methods
for the instances of a particular entity class. Entities are inserted and
updated in the PrimaryIndex by calling a method in the family of
put(E) methods. The put(E) method will insert the entity if no
entity with the same primary key already exists. If an entity with the same
primary key does exist, it will update the entity and return the existing
(old) entity. For example:
Employee oldEntity; oldEntity = primaryIndex.put(new Employee(1, "Jane Smith")); // Inserts an entity assert oldEntity == null; oldEntity = primaryIndex.put(new Employee(2, "Joan Smith")); // Inserts an entity assert oldEntity == null; oldEntity = primaryIndex.put(new Employee(2, "Joan M. Smith")); // Updates an entity assert oldEntity != null;
The putNoReturn(E) method can be used to avoid the overhead of
returning the existing entity, when the existing entity is not important to
the application. The return type of putNoReturn(E) is void. For
example:
primaryIndex.putNoReturn(new Employee(1, "Jane Smith")); // Inserts an entity primaryIndex.putNoReturn(new Employee(2, "Joan Smith")); // Inserts an entity primaryIndex.putNoReturn(new Employee(2, "Joan M. Smith")); // Updates an entity
The putNoOverwrite(E) method can be used to ensure that an existing
entity is not overwritten. putNoOverwrite(E) returns true if the
entity was inserted, or false if an existing entity exists and no action was
taken. For example:
boolean inserted; inserted = primaryIndex.putNoOverwrite(new Employee(1, "Jane Smith")); // Inserts an entity assert inserted; inserted = primaryIndex.putNoOverwrite(new Employee(2, "Joan Smith")); // Inserts an entity assert inserted; inserted = primaryIndex.putNoOverwrite(new Employee(2, "Joan M. Smith")); // No action was taken! assert !inserted;
Primary key values must be unique, in other words, each instance of a
given entity class must have a distinct primary key value. Rather than
assigning the unique primary key values yourself, a sequence can be
used to assign sequential integer values automatically, starting with the
value 1 (one). A sequence is defined using the PrimaryKey.sequence()
annotation property. For example:
@Entity
class Employee {
@PrimaryKey(sequence="ID")
long id;
String name;
Employee(String name) {
this.name = name;
}
private Employee() {} // For bindings
}
The name of the sequence used above is "ID". Any name can be used. If
the same sequence name is used in more than one entity class, the sequence
will be shared by those classes, in other words, a single sequence of
integers will be used for all instances of those classes. See PrimaryKey.sequence() for more information.
Any method in the family of put(E) methods may be used to insert
entities where the primary key is assigned from a sequence. When the put(E) method returns, the primary key field of the entity object will be set
to the assigned key value. For example:
Employee employee;
employee = new Employee("Jane Smith");
primaryIndex.putNoReturn(employee); // Inserts an entity
assert employee.id == 1;
employee = new Employee("Joan Smith");
primaryIndex.putNoReturn(employee); // Inserts an entity
assert employee.id == 2;
This begs the question: How do you update an existing entity, without
assigning a new primary key? The answer is that the put(E) methods
will only assign a new key from the sequence if the primary key field is
zero or null (for reference types). If an entity with a non-zero and
non-null key field is passed to a put(E) method, any existing entity
with that primary key value will be updated. For example:
Employee employee;
employee = new Employee("Jane Smith");
primaryIndex.putNoReturn(employee); // Inserts an entity
assert employee.id == 1;
employee = new Employee("Joan Smith");
primaryIndex.putNoReturn(employee); // Inserts an entity
assert employee.id == 2;
employee.name = "Joan M. Smith";
primaryIndex.putNoReturn(employee); // Updates an existing entity
assert employee.id == 2;
Since PrimaryIndex implements the EntityIndex interface,
it shares the common index methods for retrieving and deleting entities,
opening cursors and using transactions. See EntityIndex for more
information on these topics.
Note that when using an index, keys and values are stored and retrieved by value not by reference. In other words, if an entity object is stored and then retrieved, or retrieved twice, each object will be a separate instance. For example, in the code below the assertion will always fail.
MyKey key = ...; MyEntity entity1 = new MyEntity(key, ...); index.put(entity1); MyEntity entity2 = index.get(key); assert entity1 == entity2; // always fails!
| Constructor Summary | |
|---|---|
PrimaryIndex(Database database,
Class<PK> keyClass,
EntryBinding<PK> keyBinding,
Class<E> entityClass,
EntityBinding<E> entityBinding)
Creates a primary index without using an EntityStore. |
|
| Method Summary | |
|---|---|
boolean |
contains(K key)
Checks for existence of a key in this index. |
boolean |
contains(Transaction txn,
K key,
LockMode lockMode)
Checks for existence of a key in this index. |
long |
count()
Returns a non-transactional count of the entities in this index. |
boolean |
delete(K key)
Deletes all entities with a given index key. |
boolean |
delete(Transaction txn,
K key)
Deletes all entities with a given index key. |
EntityCursor<E> |
entities()
Opens a cursor for traversing all entities in this index. |
EntityCursor<E> |
entities(K fromKey,
boolean fromInclusive,
K toKey,
boolean toInclusive)
Opens a cursor for traversing entities in a key range. |
EntityCursor<E> |
entities(Transaction txn,
CursorConfig config)
Opens a cursor for traversing all entities in this index. |
EntityCursor<E> |
entities(Transaction txn,
K fromKey,
boolean fromInclusive,
K toKey,
boolean toInclusive,
CursorConfig config)
Opens a cursor for traversing entities in a key range. |
E |
get(PK key)
Gets an entity via a key of this index. |
E |
get(Transaction txn,
PK key,
LockMode lockMode)
Gets an entity via a key of this index. |
Database |
getDatabase()
Returns the underlying database for this index. |
EntityBinding<E> |
getEntityBinding()
Returns the entity binding for this index. |
Class<E> |
getEntityClass()
Returns the entity class for this index. |
EntryBinding<PK> |
getKeyBinding()
Returns the primary key binding for this index. |
Class<PK> |
getKeyClass()
Returns the primary key class for this index. |
EntityCursor<K> |
keys()
Opens a cursor for traversing all keys in this index. |
EntityCursor<K> |
keys(K fromKey,
boolean fromInclusive,
K toKey,
boolean toInclusive)
Opens a cursor for traversing keys in a key range. |
EntityCursor<K> |
keys(Transaction txn,
CursorConfig config)
Opens a cursor for traversing all keys in this index. |
EntityCursor<K> |
keys(Transaction txn,
K fromKey,
boolean fromInclusive,
K toKey,
boolean toInclusive,
CursorConfig config)
Opens a cursor for traversing keys in a key range. |
Map<PK,E> |
map()
Returns a standard Java map based on this entity index. |
E |
put(E entity)
Inserts an entity and returns null, or updates it if the primary key already exists and returns the existing entity. |
E |
put(Transaction txn,
E entity)
Inserts an entity and returns null, or updates it if the primary key already exists and returns the existing entity. |
boolean |
putNoOverwrite(E entity)
Inserts an entity and returns true, or returns false if the primary key already exists. |
boolean |
putNoOverwrite(Transaction txn,
E entity)
Inserts an entity and returns true, or returns false if the primary key already exists. |
void |
putNoReturn(E entity)
Inserts an entity, or updates it if the primary key already exists (does not return the existing entity). |
void |
putNoReturn(Transaction txn,
E entity)
Inserts an entity, or updates it if the primary key already exists (does not return the existing entity). |
SortedMap<PK,E> |
sortedMap()
Returns a standard Java sorted map based on this entity index. |
| Methods inherited from class java.lang.Object |
|---|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
| Constructor Detail |
|---|
public PrimaryIndex(Database database,
Class<PK> keyClass,
EntryBinding<PK> keyBinding,
Class<E> entityClass,
EntityBinding<E> entityBinding)
throws DatabaseException
EntityStore.
This constructor is not normally needed and is provided for
applications that wish to use custom bindings along with the Direct
Persistence Layer. Normally, getPrimaryIndex is used instead.
Note that when this constructor is used directly, primary keys cannot
be automatically assigned from a sequence. The key assignment feature
requires knowledge of the primary key field, which is only available if
an EntityStore is used. Of course, primary keys may be
assigned from a sequence manually before calling the put
methods in this class.
database - the primary database.keyClass - the class of the primary key.keyBinding - the binding to be used for primary keys.entityClass - the class of the entities stored in this index.entityBinding - the binding to be used for entities.
DatabaseException| Method Detail |
|---|
public Database getDatabase()
public Class<PK> getKeyClass()
public EntryBinding<PK> getKeyBinding()
public Class<E> getEntityClass()
public EntityBinding<E> getEntityBinding()
public E put(E entity)
throws DatabaseException
If a PrimaryKey.sequence() is used and the primary key field of
the given entity is null or zero, this method will assign the next value
from the sequence to the primary key field of the given entity.
Auto-commit is used implicitly if the store is transactional.
entity - the entity to be inserted or updated.
DatabaseException
public E put(Transaction txn,
E entity)
throws DatabaseException
If a PrimaryKey.sequence() is used and the primary key field of
the given entity is null or zero, this method will assign the next value
from the sequence to the primary key field of the given entity.
txn - the transaction used to protect this operation, null to use
auto-commit, or null if the store is non-transactional.entity - the entity to be inserted or updated.
DatabaseException
public void putNoReturn(E entity)
throws DatabaseException
put(Object) to save the overhead of returning the existing
entity.
If a PrimaryKey.sequence() is used and the primary key field of
the given entity is null or zero, this method will assign the next value
from the sequence to the primary key field of the given entity.
Auto-commit is used implicitly if the store is transactional.
entity - the entity to be inserted or updated.
DatabaseException
public void putNoReturn(Transaction txn,
E entity)
throws DatabaseException
put(Transaction,Object) to save the overhead of returning the
existing entity.
If a PrimaryKey.sequence() is used and the primary key field of
the given entity is null or zero, this method will assign the next value
from the sequence to the primary key field of the given entity.
txn - the transaction used to protect this operation, null to use
auto-commit, or null if the store is non-transactional.entity - the entity to be inserted or updated.
DatabaseException
public boolean putNoOverwrite(E entity)
throws DatabaseException
If a PrimaryKey.sequence() is used and the primary key field of
the given entity is null or zero, this method will assign the next value
from the sequence to the primary key field of the given entity.
Auto-commit is used implicitly if the store is transactional.
entity - the entity to be inserted.
DatabaseException
public boolean putNoOverwrite(Transaction txn,
E entity)
throws DatabaseException
If a PrimaryKey.sequence() is used and the primary key field of
the given entity is null or zero, this method will assign the next value
from the sequence to the primary key field of the given entity.
txn - the transaction used to protect this operation, null to use
auto-commit, or null if the store is non-transactional.entity - the entity to be inserted.
DatabaseException
public E get(PK key)
throws DatabaseException
EntityIndexThe operation will not be transaction protected, and LockMode.DEFAULT is used implicitly.
key - the key to search for.
DatabaseException
public E get(Transaction txn,
PK key,
LockMode lockMode)
throws DatabaseException
EntityIndex
txn - the transaction used to protect this operation, or null
if the operation should not be transaction protected.key - the key to search for.lockMode - the lock mode to use for this operation, or null to
use LockMode.DEFAULT.
DatabaseExceptionpublic Map<PK,E> map()
EntityIndexStoredMap returned is defined by the Collections API. Stored collections conform
to the standard Java collections framework interface.
public SortedMap<PK,E> sortedMap()
EntityIndexStoredSortedMap returned is defined by the Collections API. Stored collections conform
to the standard Java collections framework interface.
public boolean contains(K key)
throws DatabaseException
EntityIndexThe operation will not be transaction protected, and LockMode.DEFAULT is used implicitly.
contains in interface EntityIndex<K,E>key - the key to search for.
DatabaseException
public boolean contains(Transaction txn,
K key,
LockMode lockMode)
throws DatabaseException
EntityIndex
contains in interface EntityIndex<K,E>txn - the transaction used to protect this operation, or null
if the operation should not be transaction protected.key - the key to search for.lockMode - the lock mode to use for this operation, or null to
use LockMode.DEFAULT.
DatabaseException
public long count()
throws DatabaseException
EntityIndexThis operation is faster than obtaining a count by scanning the index manually, and will not perturb the current contents of the cache. However, the count is not guaranteed to be accurate if there are concurrent updates.
count in interface EntityIndex<K,E>DatabaseException
public boolean delete(K key)
throws DatabaseException
EntityIndexAuto-commit is used implicitly if the store is transactional.
delete in interface EntityIndex<K,E>key - the key to search for.
DatabaseException
public boolean delete(Transaction txn,
K key)
throws DatabaseException
EntityIndex
delete in interface EntityIndex<K,E>txn - the transaction used to protect this operation, null to use
auto-commit, or null if the store is non-transactional.key - the key to search for.
DatabaseException
public EntityCursor<K> keys()
throws DatabaseException
EntityIndexThe operations performed with the cursor will not be transaction
protected, and CursorConfig.DEFAULT is used implicitly. If the
store is transactional, the cursor may not be used to update or delete
entities.
keys in interface EntityIndex<K,E>DatabaseException
public EntityCursor<K> keys(Transaction txn,
CursorConfig config)
throws DatabaseException
EntityIndex
keys in interface EntityIndex<K,E>txn - the transaction used to protect all operations performed with
the cursor, or null if the operations should not be transaction
protected. If null is specified and the store is transactional, the
cursor may not be used to update or delete entities.config - the cursor configuration that determines the default lock
mode used for all cursor operations, or null to implicitly use CursorConfig.DEFAULT.
DatabaseException
public EntityCursor<E> entities()
throws DatabaseException
EntityIndexThe operations performed with the cursor will not be transaction
protected, and CursorConfig.DEFAULT is used implicitly. If the
store is transactional, the cursor may not be used to update or delete
entities.
entities in interface EntityIndex<K,E>DatabaseException
public EntityCursor<E> entities(Transaction txn,
CursorConfig config)
throws DatabaseException
EntityIndex
entities in interface EntityIndex<K,E>txn - the transaction used to protect all operations performed with
the cursor, or null if the operations should not be transaction
protected. If null is specified and the store is transactional, the
cursor may not be used to update or delete entities.config - the cursor configuration that determines the default lock
mode used for all cursor operations, or null to implicitly use CursorConfig.DEFAULT.
DatabaseException
public EntityCursor<K> keys(K fromKey,
boolean fromInclusive,
K toKey,
boolean toInclusive)
throws DatabaseException
EntityIndexThe operations performed with the cursor will not be transaction
protected, and CursorConfig.DEFAULT is used implicitly. If the
store is transactional, the cursor may not be used to update or delete
entities.
keys in interface EntityIndex<K,E>fromKey - is the lower bound of the key range, or null if the range
has no lower bound.fromInclusive - is true if keys greater than or equal to fromKey
should be included in the key range, or false if only keys greater than
fromKey should be included.toKey - is the upper bound of the key range, or null if the range
has no upper bound.toInclusive - is true if keys less than or equal to toKey should be
included in the key range, or false if only keys less than toKey should
be included.
DatabaseException
public EntityCursor<K> keys(Transaction txn,
K fromKey,
boolean fromInclusive,
K toKey,
boolean toInclusive,
CursorConfig config)
throws DatabaseException
EntityIndex
keys in interface EntityIndex<K,E>txn - the transaction used to protect all operations performed with
the cursor, or null if the operations should not be transaction
protected. If null is specified and the store is transactional, the
cursor may not be used to update or delete entities.fromKey - is the lower bound of the key range, or null if the range
has no lower bound.fromInclusive - is true if keys greater than or equal to fromKey
should be included in the key range, or false if only keys greater than
fromKey should be included.toKey - is the upper bound of the key range, or null if the range
has no upper bound.toInclusive - is true if keys less than or equal to toKey should be
included in the key range, or false if only keys less than toKey should
be included.config - the cursor configuration that determines the default lock
mode used for all cursor operations, or null to implicitly use CursorConfig.DEFAULT.
DatabaseException
public EntityCursor<E> entities(K fromKey,
boolean fromInclusive,
K toKey,
boolean toInclusive)
throws DatabaseException
EntityIndexThe operations performed with the cursor will not be transaction
protected, and CursorConfig.DEFAULT is used implicitly. If the
store is transactional, the cursor may not be used to update or delete
entities.
entities in interface EntityIndex<K,E>fromKey - is the lower bound of the key range, or null if the range
has no lower bound.fromInclusive - is true if keys greater than or equal to fromKey
should be included in the key range, or false if only keys greater than
fromKey should be included.toKey - is the upper bound of the key range, or null if the range
has no upper bound.toInclusive - is true if keys less than or equal to toKey should be
included in the key range, or false if only keys less than toKey should
be included.
DatabaseException
public EntityCursor<E> entities(Transaction txn,
K fromKey,
boolean fromInclusive,
K toKey,
boolean toInclusive,
CursorConfig config)
throws DatabaseException
EntityIndex
entities in interface EntityIndex<K,E>txn - the transaction used to protect all operations performed with
the cursor, or null if the operations should not be transaction
protected. If null is specified and the store is transactional, the
cursor may not be used to update or delete entities.fromKey - is the lower bound of the key range, or null if the range
has no lower bound.fromInclusive - is true if keys greater than or equal to fromKey
should be included in the key range, or false if only keys greater than
fromKey should be included.toKey - is the upper bound of the key range, or null if the range
has no upper bound.toInclusive - is true if keys less than or equal to toKey should be
included in the key range, or false if only keys less than toKey should
be included.config - the cursor configuration that determines the default lock
mode used for all cursor operations, or null to implicitly use CursorConfig.DEFAULT.
DatabaseException
|
Berkeley DB version 4.8.30 |
|||||||||
| PREV CLASS NEXT CLASS | FRAMES NO FRAMES | |||||||||
| SUMMARY: NESTED | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD | |||||||||