public void addAttributeConverterDefinition(AttributeConverterDefinition definition) {
if (this.attributeConverterDefinitionsByClass == null) {
this.attributeConverterDefinitionsByClass =
new HashMap<Class, AttributeConverterDefinition>();
}
final Object old =
this.attributeConverterDefinitionsByClass.put(
definition.getAttributeConverter().getClass(), definition);
if (old != null) {
throw new AssertionFailure(
String.format(
"AttributeConverter class [%s] registered multiple times",
definition.getAttributeConverter().getClass()));
}
}
/**
* Build a Hibernate Type that incorporates the JPA AttributeConverter. AttributeConverter works
* totally in memory, meaning it converts between one Java representation (the entity attribute
* representation) and another (the value bound into JDBC statements or extracted from results).
* However, the Hibernate Type system operates at the lower level of actually dealing directly
* with those JDBC objects. So even though we have an AttributeConverter, we still need to "fill
* out" the rest of the BasicType data and bridge calls to bind/extract through the converter.
*
* <p>Essentially the idea here is that an intermediate Java type needs to be used. Let's use an
* example as a means to illustrate... Consider an {@code AttributeConverter<Integer,String>}.
* This tells Hibernate that the domain model defines this attribute as an Integer value (the
* 'entityAttributeJavaType'), but that we need to treat the value as a String (the
* 'databaseColumnJavaType') when dealing with JDBC (aka, the database type is a VARCHAR/CHAR):
*
* <ul>
* <li>When binding values to PreparedStatements we need to convert the Integer value from the
* entity into a String and pass that String to setString. The conversion is handled by
* calling {@link AttributeConverter#convertToDatabaseColumn(Object)}
* <li>When extracting values from ResultSets (or CallableStatement parameters) we need to
* handle the value via getString, and convert that returned String to an Integer. That
* conversion is handled by calling {@link
* AttributeConverter#convertToEntityAttribute(Object)}
* </ul>
*
* @return The built AttributeConverter -> Type adapter
* @todo : ultimately I want to see attributeConverterJavaType and attributeConverterJdbcTypeCode
* specify-able separately then we can "play them against each other" in terms of determining
* proper typing
* @todo : see if we already have previously built a custom on-the-fly BasicType for this
* AttributeConverter; see note below about caching
*/
@SuppressWarnings("unchecked")
private Type buildAttributeConverterTypeAdapter() {
// todo : validate the number of columns present here?
final Class entityAttributeJavaType = attributeConverterDefinition.getEntityAttributeType();
final Class databaseColumnJavaType = attributeConverterDefinition.getDatabaseColumnType();
// resolve the JavaTypeDescriptor
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// For the JavaTypeDescriptor portion we simply resolve the "entity attribute representation"
// part of
// the AttributeConverter to resolve the corresponding descriptor.
final JavaTypeDescriptor entityAttributeJavaTypeDescriptor =
JavaTypeDescriptorRegistry.INSTANCE.getDescriptor(entityAttributeJavaType);
// build the SqlTypeDescriptor adapter
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// Going back to the illustration, this should be a SqlTypeDescriptor that handles the Integer
// <-> String
// conversions. This is the more complicated piece. First we need to determine the JDBC type
// code
// corresponding to the AttributeConverter's declared "databaseColumnJavaType" (how we read
// that value out
// of ResultSets). See JdbcTypeJavaClassMappings for details. Again, given example, this
// should return
// VARCHAR/CHAR
int jdbcTypeCode =
JdbcTypeJavaClassMappings.INSTANCE.determineJdbcTypeCodeForJavaClass(
databaseColumnJavaType);
if (isNationalized()) {
jdbcTypeCode =
NationalizedTypeMappings.INSTANCE.getCorrespondingNationalizedCode(jdbcTypeCode);
}
// find the standard SqlTypeDescriptor for that JDBC type code.
final SqlTypeDescriptor sqlTypeDescriptor =
SqlTypeDescriptorRegistry.INSTANCE.getDescriptor(jdbcTypeCode);
// find the JavaTypeDescriptor representing the "intermediate database type representation".
// Back to the
// illustration, this should be the type descriptor for Strings
final JavaTypeDescriptor intermediateJavaTypeDescriptor =
JavaTypeDescriptorRegistry.INSTANCE.getDescriptor(databaseColumnJavaType);
// and finally construct the adapter, which injects the AttributeConverter calls into the
// binding/extraction
// process...
final SqlTypeDescriptor sqlTypeDescriptorAdapter =
new AttributeConverterSqlTypeDescriptorAdapter(
attributeConverterDefinition.getAttributeConverter(),
sqlTypeDescriptor,
intermediateJavaTypeDescriptor);
// todo : cache the AttributeConverterTypeAdapter in case that AttributeConverter is applied
// multiple times.
final String name =
AttributeConverterTypeAdapter.NAME_PREFIX
+ attributeConverterDefinition.getAttributeConverter().getClass().getName();
final String description =
String.format(
"BasicType adapter for AttributeConverter<%s,%s>",
entityAttributeJavaType.getSimpleName(), databaseColumnJavaType.getSimpleName());
return new AttributeConverterTypeAdapter(
name,
description,
attributeConverterDefinition.getAttributeConverter(),
sqlTypeDescriptorAdapter,
entityAttributeJavaType,
databaseColumnJavaType,
entityAttributeJavaTypeDescriptor);
}
@Override
public MetadataBuilder applyAttributeConverter(AttributeConverter attributeConverter) {
applyAttributeConverter(AttributeConverterDefinition.from(attributeConverter));
return this;
}
@Override
public MetadataBuilder applyAttributeConverter(
AttributeConverter attributeConverter, boolean autoApply) {
applyAttributeConverter(AttributeConverterDefinition.from(attributeConverter, autoApply));
return this;
}
@Override
public MetadataBuilder applyAttributeConverter(
Class<? extends AttributeConverter> attributeConverterClass, boolean autoApply) {
applyAttributeConverter(AttributeConverterDefinition.from(attributeConverterClass, autoApply));
return this;
}