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Java > Open Source Codes > org > apache > tapestry > callback > PageCallback


1 // Copyright 2004, 2005 The Apache Software Foundation
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 // http://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14
15 package org.apache.tapestry.callback;
16
17 import org.apache.hivemind.util.Defense;
18 import org.apache.tapestry.IPage;
19 import org.apache.tapestry.IRequestCycle;
20
21 /**
22  * Simple callback for returning to a page.
23  * <p>
24  * Example usage of <tt>PageCallback</tt>:
25  * <p>
26  * The Home page ensure a user is authenticated in the
27  * {@link org.apache.tapestry.IPage#validate(IRequestCycle)} method. If the user is not
28  * authenticated, they are redirected to the Login page, after setting a callback in the Login page.
29  * <p>
30  * The Login page <tt>formSubmit()</tt> {@link org.apache.tapestry.IActionListener} authenticates
31  * the user and then invokes {@link ICallback#performCallback(IRequestCycle)} to the Home page.
32  *
33  * <pre>
34  *
35  *
36  * public class Home extends BasePage {
37  *
38  * public void validate(IRequestCycle cycle) {
39  * Visit visit = (Visit) getVisit();
40  *
41  * if (!visit.isAuthenticated()) {
42  * Login login = (Login) cycle.getPage(&quot;Login&quot;);
43  *
44  * login.setCallback(new PageCallback(this));
45  *
46  * throw new PageRedirectException(login);
47  * }
48  * }
49  * }
50  *
51  * public Login extends BasePage {
52  *
53  * private ICallback _callback;
54  *
55  * public void setCallback(ICallback _callback) {
56  * _callback = callback;
57  * }
58  *
59  * public void formSubmit(IRequestCycle cycle) {
60  * // Authentication code
61  * ..
62  *
63  * Visit visit = (Visit) getVisit();
64  *
65  * visit.setAuthenticated(true);
66  *
67  * if (_callback != null) {
68  * _callback.performCallback(cycle);
69  * }
70  * }
71  * }
72  *
73  *
74  * </pre>
75  *
76  * @author Howard Lewis Ship
77  * @since 0.2.9
78  */
79
80 public class PageCallback implements ICallback
81 {
82     /**
83      * @since 2.0.4
84      */
85
86     private static final long serialVersionUID = -3286806776105690068L;
87
88     private String JavaDoc _pageName;
89
90     public PageCallback(String JavaDoc pageName)
91     {
92         Defense.notNull(pageName, "pageName");
93         _pageName = pageName;
94     }
95
96     public PageCallback(IPage page)
97     {
98         Defense.notNull(page, "page");
99
100         _pageName = page.getPageName();
101     }
102
103     public String JavaDoc toString()
104     {
105         return "PageCallback[" + _pageName + "]";
106     }
107
108     /**
109      * Invokes {@link IRequestCycle#activate(String)} to select the previously identified page as
110      * the response page.
111      */
112
113     public void performCallback(IRequestCycle cycle)
114     {
115         Defense.notNull(cycle, "cycle");
116
117         cycle.activate(_pageName);
118     }
119 }
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