1+ /*
2+ * Copyright 2006-2007 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+ package org .springframework .batch .core .scope ;
17+
18+ import org .apache .commons .logging .Log ;
19+ import org .apache .commons .logging .LogFactory ;
20+ import org .springframework .batch .core .scope .context .JobContext ;
21+ import org .springframework .batch .core .scope .context .JobSynchronizationManager ;
22+ import org .springframework .batch .core .scope .util .ContextFactory ;
23+ import org .springframework .batch .core .scope .util .JobContextFactory ;
24+ import org .springframework .beans .BeanWrapper ;
25+ import org .springframework .beans .BeanWrapperImpl ;
26+ import org .springframework .beans .factory .ObjectFactory ;
27+ import org .springframework .beans .factory .config .Scope ;
28+
29+ /**
30+ * Scope for job context. Objects in this scope use the Spring container as an
31+ * object factory, so there is only one instance of such a bean per executing
32+ * job. All objects in this scope are <aop:scoped-proxy/> (no need to
33+ * decorate the bean definitions).<br/>
34+ * <br/>
35+ *
36+ * In addition, support is provided for late binding of references accessible
37+ * from the {@link JobContext} using #{..} placeholders. Using this feature,
38+ * bean properties can be pulled from the job or job execution context and the
39+ * job parameters. E.g.
40+ *
41+ * <pre>
42+ * <bean id="..." class="..." scope="job">
43+ * <property name="name" value="#{jobParameters[input]}" />
44+ * </bean>
45+ *
46+ * <bean id="..." class="..." scope="job">
47+ * <property name="name" value="#{jobExecutionContext['input.stem']}.txt" />
48+ * </bean>
49+ * </pre>
50+ *
51+ * The {@link JobContext} is referenced using standard bean property paths (as
52+ * per {@link BeanWrapper}). The examples above all show the use of the Map
53+ * accessors provided as a convenience for job attributes.
54+ *
55+ * @author Dave Syer
56+ * @author Jimmy Praet (create JobScope based on {@link StepScope})
57+ * @since 2.0
58+ */
59+ public class JobScope extends ScopeSupport {
60+
61+ private Log logger = LogFactory .getLog (getClass ());
62+
63+ private final Object mutex = new Object ();
64+
65+ /**
66+ * Context key for clients to use for conversation identifier.
67+ */
68+ public static final String ID_KEY = "JOB_IDENTIFIER" ;
69+
70+ /**
71+ * The ContextFactory.
72+ */
73+ private static final ContextFactory CONTEXT_FACTORY = new JobContextFactory ();
74+
75+ public JobScope () {
76+ super ("job" , CONTEXT_FACTORY );
77+ }
78+
79+ /**
80+ * If Spring 3.0 is available, this will be used to resolve expressions in
81+ * job-scoped beans. This method is part of the Scope SPI in Spring 3.0,
82+ * but should just be ignored by earlier versions of Spring.
83+ */
84+ public Object resolveContextualObject (String key ) {
85+ JobContext context = getContext ();
86+ // TODO: support for attributes as well maybe (setters not exposed yet
87+ // so not urgent).
88+ return new BeanWrapperImpl (context ).getPropertyValue (key );
89+ }
90+
91+ /**
92+ * @see Scope#get(String, ObjectFactory)
93+ */
94+ public Object get (String name , ObjectFactory objectFactory ) {
95+
96+ JobContext context = getContext ();
97+ Object scopedObject = context .getAttribute (name );
98+
99+ if (scopedObject == null ) {
100+
101+ synchronized (mutex ) {
102+ scopedObject = context .getAttribute (name );
103+ if (scopedObject == null ) {
104+
105+ logger .debug (String .format ("Creating object in scope=%s, name=%s" , this .getName (), name ));
106+
107+ scopedObject = objectFactory .getObject ();
108+ context .setAttribute (name , scopedObject );
109+
110+ }
111+
112+ }
113+
114+ }
115+ return scopedObject ;
116+ }
117+
118+ /**
119+ * @see Scope#getConversationId()
120+ */
121+ public String getConversationId () {
122+ JobContext context = getContext ();
123+ return context .getId ();
124+ }
125+
126+ /**
127+ * @see Scope#registerDestructionCallback(String, Runnable)
128+ */
129+ public void registerDestructionCallback (String name , Runnable callback ) {
130+ JobContext context = getContext ();
131+ logger .debug (String .format ("Registered destruction callback in scope=%s, name=%s" , this .getName (), name ));
132+ context .registerDestructionCallback (name , callback );
133+ }
134+
135+ /**
136+ * @see Scope#remove(String)
137+ */
138+ public Object remove (String name ) {
139+ JobContext context = getContext ();
140+ logger .debug (String .format ("Removing from scope=%s, name=%s" , this .getName (), name ));
141+ return context .removeAttribute (name );
142+ }
143+
144+ /**
145+ * Get an attribute accessor in the form of a {@link JobContext} that can
146+ * be used to store scoped bean instances.
147+ *
148+ * @return the current job context which we can use as a scope storage
149+ * medium
150+ */
151+ private JobContext getContext () {
152+ JobContext context = JobSynchronizationManager .getContext ();
153+ if (context == null ) {
154+ throw new IllegalStateException ("No context holder available for job scope" );
155+ }
156+ return context ;
157+ }
158+
159+ }
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