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Java > Open Source Codes > org > apache > cocoon > components > flow > FlowHelper


1 /*
2  * Copyright 1999-2004 The Apache Software Foundation.
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.apache.cocoon.components.flow;
17
18 import org.mozilla.javascript.Undefined;
19 import org.mozilla.javascript.Wrapper;
20
21 import java.util.Map JavaDoc;
22
23 /**
24  * Provides the interface between the flow controller layer and the
25  * view layer. A view can obtain the context object sent by a flow
26  * script and the current web continuation, if any.
27  */
28 public class FlowHelper {
29
30     // Constants defining keys in the object model used to store the various objects.
31 // These constants are private so that access to these objects only go through the
32 // accessors provided below.
33 //
34 // These objects are stored in the object model rather than as request attributes,
35 // as object model is cloned for subrequests (see EnvironmentWrapper), whereas
36 // request attributes are shared between the "real" request and all of its
37 // child requests.
38
39     /**
40      * Request attribute name used to store flow context.
41      */
42     private static final String JavaDoc CONTEXT_OBJECT = "cocoon.flow.context";
43
44     /**
45      * Request attribute name used to store flow continuation.
46      */
47     private static final String JavaDoc CONTINUATION_OBJECT = "cocoon.flow.continuation";
48
49     /**
50      * Get the flow context object associated with the current request
51      *
52      * @param objectModel The Cocoon Environment's object model
53      * @return The context object
54      */
55     public final static Object JavaDoc getContextObject(Map JavaDoc objectModel) {
56         return objectModel.get(CONTEXT_OBJECT);
57     }
58
59     /**
60      * Get the web continuation associated with the current request
61      *
62      * @param objectModel The Cocoon Environment's object model
63      * @return The web continuation
64      */
65     public final static WebContinuation getWebContinuation(Map JavaDoc objectModel) {
66         return (WebContinuation)objectModel.get(CONTINUATION_OBJECT);
67     }
68
69     /**
70      * Set the web continuation associated with the current request
71      *
72      * @param objectModel The Cocoon Environment's object model
73      * @param kont The web continuation
74      */
75     public final static void setWebContinuation(Map JavaDoc objectModel,
76                                           WebContinuation kont) {
77         objectModel.put(CONTINUATION_OBJECT, kont);
78     }
79
80     /**
81      * Set the flow context object associated with the current request
82      *
83      * @param objectModel The Cocoon Environment's object model
84      * @param obj The context object
85      */
86     public final static void setContextObject(Map JavaDoc objectModel, Object JavaDoc obj) {
87         objectModel.put(CONTEXT_OBJECT, obj);
88     }
89     
90     /**
91      * Unwrap a Rhino object (getting the raw java object) and convert undefined to null
92      */
93     public static Object JavaDoc unwrap(Object JavaDoc obj) {
94         if (obj instanceof Wrapper) {
95             obj = ((Wrapper)obj).unwrap();
96         } else if (obj == Undefined.instance) {
97             obj = null;
98         }
99         return obj;
100     }
101 }
102
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