Что такое JPA

Что такое JPA?

JPA – Java persistence API.
JPA реализует концепцию ORM(object-relational mapping).

Что такое Entity?

Entity – POJO класс, связанный с бд с

Что такое JPQL

JPQL – Java persistence query language. Используется для написания

Какие есть реализации JPA?

-Hibernate
-Toplink
-Eclipselink
-OpenJpa
-DataNucleus
-ObjectDb

Сравнение производительности JPA библиотек

Hibernate

Configuration properties

hibernate.dialect
hibernate.show_sql
hibernate.format_sql
hibernate.default_schema
hibernate.default_catalog
hibernate.session_factory_name
hibernate.max_fetch_depth
hibernate.default_batch_fetch_size
hibernate.default_entity_mode
hibernate.order_updates
hibernate.generate_statistics
hibernate.use_identifier_rollback
hibernate.use_sql_comments

Configuration properties

hibernate.jdbc.fetch_size
hibernate.jdbc.batch_size
hibernate.jdbc.batch_versioned_data
hibernate.jdbc.factory_class
hibernate.jdbc.use_scrollable_resultset
hibernate.jdbc.use_streams_for_binary
hibernate.jdbc.use_get_generated_keys
hibernate.connection.provider_class
hibernate.connection.isolation
hibernate.connection.autocommit
hibernate.connection.release_mode

Configuration properties

hibernate.cache.provider_class
hibernate.cache.use_minimal_puts
hibernate.cache.use_query_cache
hibernate.cache.use_second_level_cache
hibernate.cache.query_cache_factory
hibernate.cache.region_prefix
hibernate.cache.use_structured_entries

Configuration properties

hibernate.transaction.factory_class
jta.UserTransaction
hibernate.transaction.manager_lookup_class
hibernate.transaction.flush_before_completion
hibernate.transaction.auto_close_session

Configuration properties

hibernate.current_session_context_class
hibernate.query.factory_class
hibernate.query.substitutions
hibernate.hbm2ddl.auto
hibernate.cglib.use_reflection_optimizer

Dialects

org.hibernate.dialect.DB2Dialect org.hibernate.dialect.DB2400Dialect
org.hibernate.dialect.DB2390Dialect org.hibernate.dialect.PostgreSQLDialect
org.hibernate.dialect.MySQLDialect org.hibernate.dialect.MySQLInnoDBDialect
org.hibernate.dialect.MySQLMyISAMDialect org.hibernate.dialect.OracleDialect
org.hibernate.dialect.Oracle9iDialect org.hibernate.dialect.Oracle10gDialect
org.hibernate.dialect.SybaseDialect org.hibernate.dialect.SybaseAnywhereDialect
org.hibernate.dialect.SQLServerDialect org.hibernate.dialect.SAPDBDialect
org.hibernate.dialect.InformixDialect org.hibernate.dialect.HSQLDialect
org.hibernate.dialect.IngresDialect org.hibernate.dialect.ProgressDialect
org.hibernate.dialect.MckoiDialect org.hibernate.dialect.InterbaseDialect
org.hibernate.dialect.PointbaseDialect

Application Configuration

Самостоятельная работа

hibernate.cfg.xml

"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">


?
?
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JPA

javax.persistence VS org.hibernate.annotations

Entities

@Entity
@Table
@Id
@GeneratedValue
@Column
@OneToMany
@ManyToOne
@ManyToMany
@OneToOne

Entity states

Methods of session

persist, save
update, merge
delete
load, get
evict

@ManyToMany

@ManyToMany
@JoinTable(name=”?”)
@ManyToMany(mappedBy = “?”)

Cascading

CascadeType:
ALL
DETACH
MERGE
PERSIST
REFRESH
REMOVE

FetchType

Eager
Lazy

Composite PK

@Embeddable
Serializable

Additional annotations

@Transient
@OrderColumn
@NamedQuery
@NamedNativeQuery
@Sort
@OrderBy
@Where

Inheritance

Single table
Joined
Table-per-cpass

Single table(table per hierarchy)

Parent:
@Inheritance(strategy = InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(name = "?",discriminatorType = DiscriminatorType.?)
Child:
@DiscriminatorValue("dog")

Table per class(table per concrete class)

Parent:
@Inheritance(strategy = InheritanceType.TABLE_PER_CLASS)
Child:
@AttributeOverrides({
@AttributeOverride(name="?", column=@Column(name="?"))
})

Table per subclass, Joined

Parent:
@Inheritance(strategy = InheritanceType.JOINED)
Child:
@PrimaryKeyJoinColumn(name = "?", referencedColumnName = "?")

Isolation levels

Read uncommited(Dirty read, Non repeatable read, Phantom read)
Read commited(Non repeatable

Isolation levels

session.doWork(connection -> {
connection.setTransactionIsolation(Connection.?);
});

Optimistic vs pessimistic locking

@Version
where version = ?

Caching

Level 1 (session)
Level 2 (session factory)

Level 2 caching

EHCache
Infinispan
OSCache
SwarmCache
Modes:
NORMAL, GET, PUT

Level 2 caching, EHCache

POM.xml:

org.hibernate
hibernate-ehcache
?

hibernate.cfg.xml:
true
org.hibernate.cache.EhCacheProvider
org.hibernate.cache.ehcache.SingletonEhCacheRegionFactory
cache-config.xml
cache-config.xml:

HQL

from ? alias where ____
select alias.? from ?
from ? alias where

Named queries

@NamedQuery(name = "?", query="?")
session.getNamedQuery(“?”)

Pagination

query.setFirstResult
query.setMaxResults

Query ->

list
iterate
uniqueResult

Criteria api

session.createCriteria(Entity.class)
.add(Restrictions.?)
.addOrder(Order.?)
.setProjections(Projections.?)