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Java > Open Source Codes > org > springframework > webflow > executor > support > FlowExecutorArgumentExtractor


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 package org.springframework.webflow.executor.support;
17
18 import org.springframework.webflow.context.ExternalContext;
19 import org.springframework.webflow.execution.repository.FlowExecutionKey;
20 import org.springframework.webflow.executor.FlowExecutor;
21
22 /**
23  * A helper strategy used by the {@link FlowRequestHandler} to extract
24  * {@link FlowExecutor} method arguments from a request initiated by
25  * an {@link ExternalContext}. The extracted arguments were typically
26  * exposed in the previous response (the response that resulted in
27  * a new request) using a {@link FlowExecutorArgumentExposer}.
28  *
29  * @author Keith Donald
30  * @author Erwin Vervaet
31  */
32 public interface FlowExecutorArgumentExtractor {
33
34     /**
35      * Returns true if the flow id is extractable from the context.
36      * @param context the context in which a external user event occured
37      * @return true if extractable, false if not
38      */
39     public boolean isFlowIdPresent(ExternalContext context);
40
41     /**
42      * Extracts the flow id from the external context.
43      * @param context the context in which a external user event occured
44      * @return the extracted flow id
45      * @throws FlowExecutorArgumentExtractionException if the flow id could not
46      * be extracted
47      */
48     public String JavaDoc extractFlowId(ExternalContext context) throws FlowExecutorArgumentExtractionException;
49
50     /**
51      * Returns true if the flow execution key is extractable from the context.
52      * @param context the context in which a external user event occured
53      * @return true if extractable, false if not
54      */
55     public boolean isFlowExecutionKeyPresent(ExternalContext context);
56
57     /**
58      * Extract the flow execution key from the external context.
59      * @param context the context in which the external user event occured
60      * @return the obtained flow execution key
61      * @throws FlowExecutorArgumentExtractionException if the flow execution key
62      * could not be extracted
63      */
64     public String JavaDoc extractFlowExecutionKey(ExternalContext context) throws FlowExecutorArgumentExtractionException;
65
66     /**
67      * Returns true if the event id is extractable from the context.
68      * @param context the context in which a external user event occured
69      * @return true if extractable, false if not
70      */
71     public boolean isEventIdPresent(ExternalContext context);
72
73     /**
74      * Extract the flow execution event id from the external context.
75      * <p>
76      * This method should only be called if a {@link FlowExecutionKey} was
77      * successfully extracted, indicating a request to resume a flow execution.
78      * @param context the context in which a external user event occured
79      * @return the event id
80      * @throws FlowExecutorArgumentExtractionException if the event id could not
81      * be extracted
82      */
83     public String JavaDoc extractEventId(ExternalContext context) throws FlowExecutorArgumentExtractionException;
84
85 }
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