🗊Презентация Что такое JPA

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 помощью аннотации или xml конфигурации. Entity класс должен: Должен иметь пустой конструктор. Не может быть final, не может использовать final поля. Должен содержать поле @Id.

Что такое JPQL JPQL – Java persistence query language. Используется для написания sql-подобных запросов, оперирующих сущностями.

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 org.hibernate.dialect.FrontbaseDialect org.hibernate.dialect.FirebirdDialect

Application Configuration Самостоятельная работа

hibernate.cfg.xml <?xml version='1.0' encoding='utf-8'?> <!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd"> <hibernate-configuration> <session-factory> <property name="connection.driver_class">?</property> <property name="connection.url">?</property> <property name="connection.username">?</property> <property name="connection.password">?</property> <property name="connection.pool_size">?</property> <property name="dialect">?</property> <property name="show_sql">?</property> <property name="hbm2ddl.auto">?</property> <mapping class="?"/> </session-factory> </hibernate-configuration>

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 read, Phantom read) Repeatable Read(Phantom read) Serializable

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: <dependency> <groupId>org.hibernate</groupId> <artifactId>hibernate-ehcache</artifactId> <version>?</version> </dependency> hibernate.cfg.xml: <property name="cache.use_second_level_cache">true</property> <property name="cache.provider_class">org.hibernate.cache.EhCacheProvider</property> <property name="hibernate.cache.region.factory_class">org.hibernate.cache.ehcache.SingletonEhCacheRegionFactory</property> <property name="net.sf.ehcache.configurationResourceName">cache-config.xml</property> cache-config.xml: <?xml version="1.0" encoding="UTF-8"?> <ehcache> <defaultCache maxElementsInMemory="100" timeToIdleSeconds="30" timeToLiveSeconds="120" /> </ehcache>

HQL from ? alias where ____ select alias.? from ? from ? alias where param > :paramIdentifier .setParameter("paramIdentifier", ?) from ? x inner join fetch x.? as ?

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.?)

Interceptors ? extends EmptyInterceptor