CompositeUserType (Hibernate API Documentation) - Hibernate 3.2.3 正式版 API 英文文档

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org.hibernate.usertype
Interface CompositeUserType

public interface CompositeUserType

A UserType that may be dereferenced in a query. This interface allows a custom type to define "properties". These need not necessarily correspond to physical JavaBeans style properties.

A CompositeUserType may be used in almost every way that a component may be used. It may even contain many-to-one associations.

Implementors must be immutable and must declare a public default constructor.

Unlike UserType, cacheability does not depend upon serializability. Instead, assemble() and disassemble provide conversion to/from a cacheable representation.

Author:: Gavin King
See Also:: for more simple cases, Type

Method Summary

Object assemble(Serializable cached, SessionImplementor session, Object owner)
          Reconstruct an object from the cacheable representation.

Object deepCopy(Object value)
          Return a deep copy of the persistent state, stopping at entities and at collections.

Serializable disassemble(Object value, SessionImplementor session)
          Transform the object into its cacheable representation.

boolean equals(Object x, Object y)
          Compare two instances of the class mapped by this type for persistence "equality".

String[] getPropertyNames()
          Get the "property names" that may be used in a query.

Type[] getPropertyTypes()
          Get the corresponding "property types".

Object getPropertyValue(Object component, int property)
          Get the value of a property.

int hashCode(Object x)
          Get a hashcode for the instance, consistent with persistence "equality"

boolean isMutable()
          Check if objects of this type mutable.

Object nullSafeGet(ResultSet rs, String[] names, SessionImplementor session, Object owner)
          Retrieve an instance of the mapped class from a JDBC resultset.

void nullSafeSet(PreparedStatement st, Object value, int index, SessionImplementor session)
          Write an instance of the mapped class to a prepared statement.

Object replace(Object original, Object target, SessionImplementor session, Object owner)
          During merge, replace the existing (target) value in the entity we are merging to with a new (original) value from the detached entity we are merging.

Class returnedClass()
          The class returned by nullSafeGet().

void setPropertyValue(Object component, int property, Object value)
          Set the value of a property.

Method Detail

getPropertyNames

public String[] getPropertyNames()

Get the "property names" that may be used in a query.

Returns:: an array of "property names"

getPropertyTypes

public Type[] getPropertyTypes()

Get the corresponding "property types".

Returns:: an array of Hibernate types

getPropertyValue

public Object getPropertyValue(Object component,
                               int property)
                        throws HibernateException

Get the value of a property.

Parameters:: component - an instance of class mapped by this "type"; property -
Returns:: the property value
Throws:: HibernateException

setPropertyValue

public void setPropertyValue(Object component,
                             int property,
                             Object value)
                      throws HibernateException

Set the value of a property.

Parameters:: component - an instance of class mapped by this "type"; property -; value - the value to set
Throws:: HibernateException

returnedClass

public Class returnedClass()

The class returned by nullSafeGet().

Returns:: Class

equals

public boolean equals(Object x,
                      Object y)
               throws HibernateException

Compare two instances of the class mapped by this type for persistence "equality". Equality of the persistent state.

Parameters:: x -; y -
Returns:: boolean
Throws:: HibernateException

hashCode

public int hashCode(Object x)
             throws HibernateException

Get a hashcode for the instance, consistent with persistence "equality"

Throws:: HibernateException

nullSafeGet

public Object nullSafeGet(ResultSet rs,
                          String[] names,
                          SessionImplementor session,
                          Object owner)
                   throws HibernateException,
                          SQLException

Retrieve an instance of the mapped class from a JDBC resultset. Implementors should handle possibility of null values.

Parameters:: rs - a JDBC result set; names - the column names; session -; owner - the containing entity
Returns:: Object
Throws:: HibernateException; SQLException

nullSafeSet

public void nullSafeSet(PreparedStatement st,
                        Object value,
                        int index,
                        SessionImplementor session)
                 throws HibernateException,
                        SQLException

Write an instance of the mapped class to a prepared statement. Implementors should handle possibility of null values. A multi-column type should be written to parameters starting from index.

Parameters:: st - a JDBC prepared statement; value - the object to write; index - statement parameter index; session -
Throws:: HibernateException; SQLException

deepCopy

public Object deepCopy(Object value)
                throws HibernateException

Return a deep copy of the persistent state, stopping at entities and at collections.

Parameters:: value - generally a collection element or entity field
Returns:: Object a copy
Throws:: HibernateException

isMutable

public boolean isMutable()

Check if objects of this type mutable.

Returns:: boolean

disassemble

public Serializable disassemble(Object value,
                                SessionImplementor session)
                         throws HibernateException

Transform the object into its cacheable representation. At the very least this method should perform a deep copy. That may not be enough for some implementations, however; for example, associations must be cached as identifier values. (optional operation)

Parameters:: value - the object to be cached; session -
Returns:: a cachable representation of the object
Throws:: HibernateException

assemble

public Object assemble(Serializable cached,
                       SessionImplementor session,
                       Object owner)
                throws HibernateException

Reconstruct an object from the cacheable representation. At the very least this method should perform a deep copy. (optional operation)

Parameters:: cached - the object to be cached; session -; owner - the owner of the cached object
Returns:: a reconstructed object from the cachable representation
Throws:: HibernateException

replace

public Object replace(Object original,
                      Object target,
                      SessionImplementor session,
                      Object owner)
               throws HibernateException

During merge, replace the existing (target) value in the entity we are merging to with a new (original) value from the detached entity we are merging. For immutable objects, or null values, it is safe to simply return the first parameter. For mutable objects, it is safe to return a copy of the first parameter. However, since composite user types often define component values, it might make sense to recursively replace component values in the target object.

Parameters:: original -; target -; session -; owner -
Returns:
Throws:: HibernateException