EntityManagerHelper (josef 3.2.5 API)

java.lang.Object
- org.josef.jpa.EntityManagerHelper

```
@Status(stage=TEST,
        unitTests=PARTIAL)
 @Review(by="Kees Schotanus",
        at="2009-09-28")
public final class EntityManagerHelper
extends Object
```
Entity Manager Helper utility class after an example by MyEclipse.
This class contains all the methods from EntityManager that don't directly deal with a JPA Entity.
Note: This class only supports a single persistence unit. When dealing with multiple persistence units, simply cache your own [@link EntityManagerFactory instance.
By default this EntityManagerHelper uses the default persistence unit. To use a specific persistence unit, you must call the init(...) method first, with the proper persistence unit name.

Version:

1.0 $Revision: 6488 $

Author:

Kees Schotanus

Method Summary

All Methods Static Methods Concrete Methods
Modifier and Type	Method and Description
`static void`	`beginTransaction()` Begins a transaction.
`static void`	`clear()` Clear the persistence context.
`static void`	`closeEntityManager()` Closes the EntityManager.
`static void`	`commit()` Commits the transaction and clears the cache.
`static javax.persistence.Query`	`createNamedQuery(String name)` Creates a named Query.
`static <T> javax.persistence.TypedQuery<T>`	`createNamedQuery(String name, Class<T> type)` Creates a named Query.
`static javax.persistence.Query`	`createNativeQuery(String query)` Creates a native Query.
`static javax.persistence.Query`	`createNativeQuery(String query, Class<? extends Persistable> type)` Creates a native Query with resulting object of the supplied type.
`static javax.persistence.Query`	`createQuery(String query)` Creates a Query.
`static void`	`detach(Persistable persistable)` Detaches the supplied persistable by removing it from the persistence context.
`static void`	`flush()` Synchronizes the persistence context to the underlying database.
`static javax.persistence.EntityManager`	`getEntityManager()` Gets the EntityManager for this Thread.
`static javax.persistence.FlushModeType`	`getFlushMode()` Gets the flush mode, applicable to all Entities in this persistence context.
`static javax.persistence.EntityTransaction`	`getTransaction()` Gets the resource-level transaction object.
`static void`	`init(String persistenceUnitName)` Initialize this EntityManagerHelper with the supplied persistenceUnitName. You only need to call this method when you want to use another persistence unit than the default persistence unit.
`static void`	`isRollbackOnly()` Determines whether the current transaction has been marked for 'rollback only'.
`static void`	`joinTransaction()` Joins an active transaction. This method should be called on a JTA application managed EntityManager that was created outside the scope of the active transaction.
`static void`	`rollback()` Rolls back the transaction, provided a transaction is active.
`static void`	`setFlushMode(javax.persistence.FlushModeType flushMode)` Sets the flush mode, applicable to all Entities in this persistence context.
`static void`	`setRollbackOnly()` Marks the current transaction for 'rollback only'.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Method Detail
  - init
```
public static void init(String persistenceUnitName)
```
    Initialize this EntityManagerHelper with the supplied persistenceUnitName.
    You only need to call this method when you want to use another persistence unit than the default persistence unit.
    
    Parameters:
    
    persistenceUnitName - The name of the persistence unit.
    When null, the default persistence unit is used.
  - getEntityManager
```
public static javax.persistence.EntityManager getEntityManager()
```
    Gets the EntityManager for this Thread.
    
    Returns:
    
    The EntityManager.
  - closeEntityManager
```
public static void closeEntityManager()
```
    Closes the EntityManager.
    
    Throws:
    
    IllegalStateException - When the EntityManager is container-managed or has already been closed.
  - getTransaction
```
public static javax.persistence.EntityTransaction getTransaction()
```
    Gets the resource-level transaction object.
    
    Returns:
    
    The resource-level transaction object.
    
    Throws:
    
    IllegalStateException - When invoked on a JTA EntityManager.
    
    See Also:
    
    EntityManager.getTransaction()
  - beginTransaction
```
public static void beginTransaction()
```
    Begins a transaction.
    
    Throws:
    
    IllegalStateException - When a transaction is already active.
    
    See Also:
    
    EntityTransaction.begin()
  - commit
```
public static void commit()
```
    Commits the transaction and clears the cache.
    Clearing the cache may seem inefficient but it is exactly what happens when Entities are managed by a container.
    
    Throws:
    
    IllegalStateException - When the transaction is not active.
    
    javax.persistence.RollbackException - When the commit fails.
    
    See Also:
    
    EntityTransaction.commit()
  - rollback
```
public static void rollback()
```
    Rolls back the transaction, provided a transaction is active.
    
    Throws:
    
    IllegalStateException - When invoked on a JTA EntityManager.
    
    javax.persistence.PersistenceException - When an unexpected error condition is encountered.
    
    See Also:
    
    EntityTransaction.rollback()
  - setRollbackOnly
```
public static void setRollbackOnly()
```
    Marks the current transaction for 'rollback only'.
    
    Throws:
    
    IllegalStateException - When the transaction is not active.
    
    See Also:
    
    EntityTransaction.setRollbackOnly()
  - isRollbackOnly
```
public static void isRollbackOnly()
```
    Determines whether the current transaction has been marked for 'rollback only'.
    
    Throws:
    
    IllegalStateException - When the transaction is not active.
    
    See Also:
    
    EntityTransaction.getRollbackOnly()
  - joinTransaction
```
public static void joinTransaction()
```
    Joins an active transaction.
    This method should be called on a JTA application managed EntityManager that was created outside the scope of the active transaction.
    
    Throws:
    
    IllegalStateException - When the EntityManager is closed.
    
    javax.persistence.TransactionRequiredException - When there is no active transaction.
    
    See Also:
    
    EntityManager.joinTransaction()
  - createQuery
```
public static javax.persistence.Query createQuery(String query)
```
    Creates a Query.
    
    Parameters:
    
    query - The SQL query.
    
    Returns:
    
    The Query.
    
    Throws:
    
    IllegalArgumentException - When the supplied query is not valid.
    
    IllegalStateException - When the EntityManager is closed.
    
    NullPointerException - When the supplied query is null.
    
    See Also:
    
    EntityManager.createQuery(String)
  - createNamedQuery
```
public static javax.persistence.Query createNamedQuery(String name)
```
    Creates a named Query.
    
    Parameters:
    
    name - The name of the Query.
    
    Returns:
    
    The named Query.
    
    See Also:
    
    EntityManager.createNamedQuery(String)
  - createNamedQuery
```
public static <T> javax.persistence.TypedQuery<T> createNamedQuery(String name,
                                                                   Class<T> type)
```
    Creates a named Query.
    
    Type Parameters:
    
    T - The type returned by the named query.
    
    Parameters:
    
    name - The name of the Query.
    
    type - The type returned by the query.
    
    Returns:
    
    The named, typed Query.
    
    See Also:
    
    EntityManager.createNamedQuery(String, Class)
  - createNativeQuery
```
public static javax.persistence.Query createNativeQuery(String query)
```
    Creates a native Query.
    
    Parameters:
    
    query - The native SQL query.
    
    Returns:
    
    The native Query.
    
    Throws:
    
    IllegalArgumentException - When the supplied query is not valid.
    
    IllegalStateException - When the EntityManager is closed.
    
    NullPointerException - When the supplied query is null.
    
    See Also:
    
    EntityManager.createNativeQuery(String)
  - createNativeQuery
```
public static javax.persistence.Query createNativeQuery(String query,
                                                        Class<? extends Persistable> type)
```
    Creates a native Query with resulting object of the supplied type.
    
    Parameters:
    
    query - The native SQL query.
    
    type - Type of the returned objects.
    
    Returns:
    
    The native Query.
    
    Throws:
    
    IllegalArgumentException - When the supplied query is not valid.
    
    IllegalStateException - When the EntityManager is closed.
    
    NullPointerException - When the supplied query is null.
    
    See Also:
    
    EntityManager.createNativeQuery(String, Class)
  - clear
```
public static void clear()
```
    Clear the persistence context.
    This causes all managed entities to become detached.
    
    Throws:
    
    IllegalStateException - When the EntityManager is closed.
    
    See Also:
    
    EntityManager.clear()
  - flush
```
public static void flush()
```
    Synchronizes the persistence context to the underlying database.
    
    Throws:
    
    IllegalStateException - When the EntityManager is closed.
    
    javax.persistence.TransactionRequiredException - When no transaction exists.
    
    javax.persistence.PersistenceException - When the flush fails.
    
    See Also:
    
    EntityManager.flush()
  - getFlushMode
```
public static javax.persistence.FlushModeType getFlushMode()
```
    Gets the flush mode, applicable to all Entities in this persistence context.
    
    Returns:
    
    The flush mode.
    
    See Also:
    
    EntityManager.getFlushMode()
  - setFlushMode
```
public static void setFlushMode(javax.persistence.FlushModeType flushMode)
```
    Sets the flush mode, applicable to all Entities in this persistence context.
    
    Parameters:
    
    flushMode - The flush mode.
    
    Throws:
    
    IllegalStateException - When the EntityManager is closed.
    
    NullPointerException - When the supplied flushMode is null.
    
    See Also:
    
    EntityManager.setFlushMode(FlushModeType)
  - detach
```
public static void detach(Persistable persistable)
```
    Detaches the supplied persistable by removing it from the persistence context.
    
    Parameters:
    
    persistable - The persistable to detach.
    
    Throws:
    
    NullPointerException - When the supplied persistable is null.

Class EntityManagerHelper

Method Summary

Methods inherited from class java.lang.Object

Method Detail

init

getEntityManager

closeEntityManager

getTransaction

beginTransaction

commit

rollback

setRollbackOnly

isRollbackOnly

joinTransaction

createQuery

createNamedQuery

createNamedQuery

createNativeQuery

createNativeQuery

clear

flush

getFlushMode

setFlushMode

detach