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Java > Open Source Codes > org > springframework > webflow > engine > ViewSelector


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.engine;
17
18 import org.springframework.webflow.execution.RequestContext;
19 import org.springframework.webflow.execution.ViewSelection;
20
21 /**
22  * Factory that produces a new, configured {@link ViewSelection} object on each
23  * invocation, taking into account the information in the provided flow
24  * execution request context.
25  * <p>
26  * Note: this class is a runtime factory. Instances are used at flow execution
27  * time by objects like the {@link ViewState} to produce new
28  * {@link ViewSelection view selections}.
29  * <p>
30  * This class allows for easy insertion of dynamic view selection logic, for
31  * instance, letting you determine the view to render or the available model
32  * data for rendering based on contextual information.
33  *
34  * @see org.springframework.webflow.execution.ViewSelection
35  * @see org.springframework.webflow.engine.ViewState
36  * @see org.springframework.webflow.engine.EndState
37  *
38  * @author Keith Donald
39  * @author Erwin Vervaet
40  */
41 public interface ViewSelector {
42
43     /**
44      * Will the primary selection returned by 'makeEntrySelection' for the given
45      * request context be renderable in this request?
46      * <p>
47      * "Renderable" view selections typically can have 'render-actions' execute
48      * before they are created. An example would be an ApplicationView that
49      * forwards to a view template like a JSP. "Non-renderable" view selections
50      * are things like a flow execution redirect--no render actually occurs, but
51      * only a redirect--rendering happens on the new redirect request.
52      * @param context the current request context of the executing flow
53      * @return true if yes, false otherwise
54      */
55     public boolean isEntrySelectionRenderable(RequestContext context);
56
57     /**
58      * Make a new "entry" view selection for the given request context. Called
59      * when a view-state, end-state, or other interactive state type is entered.
60      * @param context the current request context of the executing flow
61      * @return the entry view selection
62      */
63     public ViewSelection makeEntrySelection(RequestContext context);
64
65     /**
66      * Reconstitute a renderable view selection for the given request context to
67      * support a ViewState 'refresh' operation.
68      * @param context the current request context of the executing flow
69      * @return the view selection
70      */
71     public ViewSelection makeRefreshSelection(RequestContext context);
72
73 }
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