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Java > Open Source Codes > org > springframework > orm > jpa > JpaCallback


1 /*
2  * Copyright 2002-2006 the original author or authors.
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  * http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16
17 package org.springframework.orm.jpa;
18
19 import javax.persistence.EntityManager;
20 import javax.persistence.PersistenceException;
21
22 /**
23  * Callback interface for JPA code. To be used with {@link JpaTemplate}'s
24  * execution method, often as anonymous classes within a method implementation.
25  * A typical implementation will call <code>EntityManager.find/merge</code>
26  * to perform some operations on persistent objects.
27  *
28  * @author Juergen Hoeller
29  * @since 2.0
30  * @see org.springframework.orm.jpa.JpaTemplate
31  * @see org.springframework.orm.jpa.JpaTransactionManager
32  */
33 public interface JpaCallback {
34
35     /**
36      * Gets called by <code>JpaTemplate.execute</code> with an active
37      * JPA <code>EntityManager</code>. Does not need to care about activating
38      * or closing the <code>EntityManager</code>, or handling transactions.
39      *
40      * <p>Note that JPA callback code will not flush any modifications to the
41      * database if not executed within a transaction. Thus, you need to make
42      * sure that JpaTransactionManager has initiated a JPA transaction when
43      * the callback gets called, at least if you want to write to the database.
44      *
45      * <p>Allows for returning a result object created within the callback,
46      * i.e. a domain object or a collection of domain objects.
47      * A thrown custom RuntimeException is treated as an application exception:
48      * It gets propagated to the caller of the template.
49      *
50      * @param em active EntityManager
51      * @return a result object, or <code>null</code> if none
52      * @throws PersistenceException if thrown by the JPA API
53      * @see org.springframework.orm.jpa.JpaTemplate#execute
54      * @see org.springframework.orm.jpa.JpaTemplate#executeFind
55      */
56     Object JavaDoc doInJpa(EntityManager em) throws PersistenceException;
57
58 }
59
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