Package org.springframework.dao.support

Class DataAccessUtils

java.lang.Object

org.springframework.dao.support.DataAccessUtils

public abstract class DataAccessUtils
extends Object

Miscellaneous utility methods for DAO implementations.

Useful with any data access technology.

Since:

1.0.2

Author:

Juergen Hoeller

Constructor Summary

Constructors

Constructor	Description
DataAccessUtils()

Method Summary

Modifier and Type	Method	Description
static int	intResult(@Nullable Collection<?> results)	Return a unique int result from the given Collection.
static long	longResult(@Nullable Collection<?> results)	Return a unique long result from the given Collection.
static <T> @Nullable T	nullableSingleResult(@Nullable Collection<T> results)	Return a single result object from the given Collection.
static <T> T	objectResult(@Nullable Collection<?> results, @Nullable Class<T> requiredType)	Return a unique result object from the given Collection.
static <T> Optional<T>	optionalResult(@Nullable Collection<T> results)	Return a single result object from the given Collection.
static <T> Optional<T>	optionalResult(@Nullable Iterator<T> results)	Return a single result object from the given Iterator.
static <T> Optional<T>	optionalResult(@Nullable Stream<T> results)	Return a single result object from the given Stream.
static <T> T	requiredSingleResult(@Nullable Collection<T> results)	Return a single result object from the given Collection.
static <T> T	requiredUniqueResult(@Nullable Collection<T> results)	Return a unique result object from the given Collection.
static <T> @Nullable T	singleResult(@Nullable Collection<T> results)	Return a single result object from the given Collection.
static <T> @Nullable T	singleResult(@Nullable Iterator<T> results)	Return a single result object from the given Iterator.
static <T> @Nullable T	singleResult(@Nullable Stream<T> results)	Return a single result object from the given Stream.
static RuntimeException	translateIfNecessary(RuntimeException rawException, PersistenceExceptionTranslator pet)	Return a translated exception if this is appropriate, otherwise return the given exception as-is.
static <T> @Nullable T	uniqueResult(@Nullable Collection<T> results)	Return a unique result object from the given Collection.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

DataAccessUtils

public DataAccessUtils()

Method Details

singleResult

public static <T> @Nullable T singleResult(@Nullable Collection<T> results)
                                    throws IncorrectResultSizeDataAccessException

Return a single result object from the given Collection.

Returns null if 0 result objects found; throws an exception if more than 1 element found.

Parameters:

results - the result Collection (can be null)

Returns:

the single result object, or null if none

Throws:

IncorrectResultSizeDataAccessException - if more than one element has been found in the given Collection

singleResult

public static <T> @Nullable T singleResult(@Nullable Stream<T> results)
                                    throws IncorrectResultSizeDataAccessException

Return a single result object from the given Stream.

Returns null if 0 result objects found; throws an exception if more than 1 element found.

Parameters:

results - the result Stream (can be null)

Returns:

the single result object, or null if none

Throws:

IncorrectResultSizeDataAccessException - if more than one element has been found in the given Stream

Since:

6.1

singleResult

public static <T> @Nullable T singleResult(@Nullable Iterator<T> results)
                                    throws IncorrectResultSizeDataAccessException

Return a single result object from the given Iterator.

Returns null if 0 result objects found; throws an exception if more than 1 element found.

Parameters:

results - the result Iterator (can be null)

Returns:

the single result object, or null if none

Throws:

IncorrectResultSizeDataAccessException - if more than one element has been found in the given Iterator

Since:

6.1

optionalResult

public static <T> Optional<T> optionalResult(@Nullable Collection<T> results)
                                      throws IncorrectResultSizeDataAccessException

Return a single result object from the given Collection.

Returns Optional.empty() if 0 result objects found; throws an exception if more than 1 element found.

Parameters:

results - the result Collection (can be null)

Returns:

the single optional result object, or Optional.empty() if none

Throws:

IncorrectResultSizeDataAccessException - if more than one element has been found in the given Collection

Since:

6.1

optionalResult

public static <T> Optional<T> optionalResult(@Nullable Stream<T> results)
                                      throws IncorrectResultSizeDataAccessException

Return a single result object from the given Stream.

Returns Optional.empty() if 0 result objects found; throws an exception if more than 1 element found.

Parameters:

results - the result Stream (can be null)

Returns:

the single optional result object, or Optional.empty() if none

Throws:

IncorrectResultSizeDataAccessException - if more than one element has been found in the given Stream

Since:

6.1

optionalResult

public static <T> Optional<T> optionalResult(@Nullable Iterator<T> results)
                                      throws IncorrectResultSizeDataAccessException

Return a single result object from the given Iterator.

Returns Optional.empty() if 0 result objects found; throws an exception if more than 1 element found.

Parameters:

results - the result Iterator (can be null)

Returns:

the single optional result object, or Optional.empty() if none

Throws:

IncorrectResultSizeDataAccessException - if more than one element has been found in the given Iterator

Since:

6.1

requiredSingleResult

public static <T> T requiredSingleResult(@Nullable Collection<T> results)
                                  throws IncorrectResultSizeDataAccessException

Return a single result object from the given Collection.

Throws an exception if 0 or more than 1 element found.

Parameters:

results - the result Collection (can be null but is not expected to contain null elements)

Returns:

the single result object

Throws:

IncorrectResultSizeDataAccessException - if more than one element has been found in the given Collection

EmptyResultDataAccessException - if no element at all has been found in the given Collection

nullableSingleResult

public static <T> @Nullable T nullableSingleResult(@Nullable Collection<T> results)
                                            throws IncorrectResultSizeDataAccessException

Return a single result object from the given Collection.

Throws an exception if 0 or more than 1 element found.

Parameters:

results - the result Collection (can be null and is also expected to contain null elements)

Returns:

the single result object

Throws:

IncorrectResultSizeDataAccessException - if more than one element has been found in the given Collection

EmptyResultDataAccessException - if no element at all has been found in the given Collection

Since:

5.0.2

uniqueResult

public static <T> @Nullable T uniqueResult(@Nullable Collection<T> results)
                                    throws IncorrectResultSizeDataAccessException

Return a unique result object from the given Collection.

Returns null if 0 result objects found; throws an exception if more than 1 instance found.

Parameters:

results - the result Collection (can be null)

Returns:

the unique result object, or null if none

Throws:

IncorrectResultSizeDataAccessException - if more than one result object has been found in the given Collection

See Also:

• CollectionUtils.hasUniqueObject(java.util.Collection<?>)

requiredUniqueResult

public static <T> T requiredUniqueResult(@Nullable Collection<T> results)
                                  throws IncorrectResultSizeDataAccessException

Return a unique result object from the given Collection.

Throws an exception if 0 or more than 1 instance found.

Parameters:

results - the result Collection (can be null but is not expected to contain null elements)

Returns:

the unique result object

Throws:

IncorrectResultSizeDataAccessException - if more than one result object has been found in the given Collection

EmptyResultDataAccessException - if no result object at all has been found in the given Collection

See Also:

• CollectionUtils.hasUniqueObject(java.util.Collection<?>)

objectResult

public static <T> T objectResult(@Nullable Collection<?> results,
 @Nullable Class<T> requiredType)
                          throws IncorrectResultSizeDataAccessException,
TypeMismatchDataAccessException

Return a unique result object from the given Collection. Throws an exception if 0 or more than 1 result objects found, of if the unique result object is not convertible to the specified required type.

Parameters:

results - the result Collection (can be null but is not expected to contain null elements)

Returns:

the unique result object

Throws:

IncorrectResultSizeDataAccessException - if more than one result object has been found in the given Collection

EmptyResultDataAccessException - if no result object at all has been found in the given Collection

TypeMismatchDataAccessException - if the unique object does not match the specified required type

intResult

public static int intResult(@Nullable Collection<?> results)
                     throws IncorrectResultSizeDataAccessException,
TypeMismatchDataAccessException

Return a unique int result from the given Collection. Throws an exception if 0 or more than 1 result objects found, of if the unique result object is not convertible to an int.

Parameters:

results - the result Collection (can be null but is not expected to contain null elements)

Returns:

the unique int result

Throws:

IncorrectResultSizeDataAccessException - if more than one result object has been found in the given Collection

EmptyResultDataAccessException - if no result object at all has been found in the given Collection

TypeMismatchDataAccessException - if the unique object in the collection is not convertible to an int

longResult

public static long longResult(@Nullable Collection<?> results)
                       throws IncorrectResultSizeDataAccessException,
TypeMismatchDataAccessException

Return a unique long result from the given Collection. Throws an exception if 0 or more than 1 result objects found, of if the unique result object is not convertible to a long.

Parameters:

results - the result Collection (can be null but is not expected to contain null elements)

Returns:

the unique long result

Throws:

IncorrectResultSizeDataAccessException - if more than one result object has been found in the given Collection

EmptyResultDataAccessException - if no result object at all has been found in the given Collection

TypeMismatchDataAccessException - if the unique object in the collection is not convertible to a long

translateIfNecessary

public static RuntimeException translateIfNecessary(RuntimeException rawException,
 PersistenceExceptionTranslator pet)

Return a translated exception if this is appropriate, otherwise return the given exception as-is.

Parameters:

rawException - an exception that we may wish to translate

pet - the PersistenceExceptionTranslator to use to perform the translation

Returns:

a translated persistence exception if translation is possible, or the raw exception if it is not