01: /*
02: * Copyright 2002-2006 the original author or authors.
03: *
04: * Licensed under the Apache License, Version 2.0 (the "License");
05: * you may not use this file except in compliance with the License.
06: * You may obtain a copy of the License at
07: *
08: * http://www.apache.org/licenses/LICENSE-2.0
09: *
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 doInJpa(EntityManager em) throws PersistenceException;
57:
58: }
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