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Java > Open Source Codes > org > apache > tapestry > form > Checkbox


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.form;
16
17 import org.apache.tapestry.IMarkupWriter;
18 import org.apache.tapestry.IRequestCycle;
19
20 /**
21  * Implements a component that manages an HTML &lt;input type=checkbox&gt; form element. [ <a
22  * HREF="../../../../../ComponentReference/Checkbox.html">Component Reference </a>]
23  *
24  * @author Howard Lewis Ship
25  * @author Paul Ferraro
26  */
27 public abstract class Checkbox extends AbstractFormComponent
28 {
29     /**
30      * @see org.apache.tapestry.form.validator.AbstractRequirableField#renderRequirableFormComponent(org.apache.tapestry.IMarkupWriter,
31      * org.apache.tapestry.IRequestCycle)
32      */
33     protected void renderFormComponent(IMarkupWriter writer, IRequestCycle cycle)
34     {
35         writer.beginEmpty("input");
36         writer.attribute("type", "checkbox");
37
38         writer.attribute("name", getName());
39
40         if (isDisabled())
41             writer.attribute("disabled", "disabled");
42
43         if (isSelected())
44             writer.attribute("checked", "checked");
45
46         renderIdAttribute(writer, cycle);
47
48         renderInformalParameters(writer, cycle);
49
50         writer.closeTag();
51     }
52
53     /**
54      * In traditional HTML, many checkboxes would have the same name but different values. Under
55      * Tapestry, it makes more sense to have different names and a fixed value. For a checkbox, we
56      * only care about whether the name appears as a request parameter.
57      */
58     protected void rewindFormComponent(IMarkupWriter writer, IRequestCycle cycle)
59     {
60         String JavaDoc value = cycle.getParameter(getName());
61
62         setSelected(value != null);
63     }
64
65     /** @since 2.2 */
66     public abstract boolean isSelected();
67
68     /** @since 2.2 */
69     public abstract void setSelected(boolean selected);
70 }
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