Hibernate

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  Explain about HibernateTemplate?

The org.springframework.orm.hibernate.HibernateTemplate class simplifies Hibernate data access code, and converts checked HibernateExceptions into unchecked DataAccessExceptions, following the org.springframework.dao exception hierarchy. Uses the same SQLExceptionTranslator mechanism as JdbcTemplate. 
The central method is execute(), supporting Hibernate access code implementing the HibernateCallback interface. It provides Hibernate Session handling such that neither the HibernateCallback implementation nor the calling code needs to explicitly care about retrieving/closing Hibernate Sessions, or handling Session lifecycle exceptions. 

  What happens when both hibernate.properties and hibernate.cfg.xml are in the classpath?

The settings of the XML configuration file will override the settings used in the properties.

  
What are the types of Hibernate instance states ?

There are three types of instance states in Hibernate:
    * Transient :-The instance is not associated with any persistence context
    * Persistent :-The instance is associated with a persistence context
    * Detached -:The instance was associated with a persistence context which has been closed – currently not associated.

  What is the use of dynamic-insert and dynamic-update attributes in a class mapping?

You may declare a persistent class using the class element. The dynamic-insert and dynamic-update attributes are optional attributes. The  dynamic-update (defaults value is false), specifies that UPDATE SQL should be generated at runtime and contain only those columns whose values have changed.
The dynamic-insert (defaults value is false), specifies that INSERT SQL should be generated at runtime and contain only the columns whose values are not null. 

  How can you map a whole class as immutable?

You can mark the class as mutable="false", Default value is true. This specifies that instances of the class are mutable. You can not update or delete immutable classes by the application.