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Java > Open Source Codes > org > apache > tapestry > wml > Select


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.wml;
16
17 import org.apache.hivemind.ApplicationRuntimeException;
18 import org.apache.hivemind.HiveMind;
19 import org.apache.tapestry.AbstractComponent;
20 import org.apache.tapestry.IMarkupWriter;
21 import org.apache.tapestry.IRequestCycle;
22 import org.apache.tapestry.Tapestry;
23
24 /**
25  * The Select element lets users pick from a list of options. Each option is specified by an Option
26  * element. Each Option element may have one line of formatted text (which may be wrapped or
27  * truncated by the user agent if too long). Unless multiple selections are required it is generally
28  * easier to use the {@link PropertySelection}component.
29  *
30  * @author David Solis
31  * @since 3.0
32  */
33 public abstract class Select extends AbstractComponent
34 {
35     /**
36      * Used by the <code>Select</code> to record itself as a {@link IRequestCycle}attribute, so
37      * that the {@link Option}components it wraps can have access to it.
38      */
39
40     private final static String JavaDoc ATTRIBUTE_NAME = "org.apache.tapestry.active.Select";
41
42     /**
43      * @see org.apache.tapestry.AbstractComponent#renderComponent(IMarkupWriter, IRequestCycle)
44      */
45
46     protected void renderComponent(IMarkupWriter writer, IRequestCycle cycle)
47     {
48         if (cycle.getAttribute(ATTRIBUTE_NAME) != null)
49             throw new ApplicationRuntimeException(Tapestry.getMessage("Select.may-not-nest"), this,
50                     null, null);
51
52         cycle.setAttribute(ATTRIBUTE_NAME, this);
53
54         boolean render = !cycle.isRewinding();
55
56         if (render)
57         {
58             writer.begin("select");
59
60             writer.attribute("name", getName());
61
62             String JavaDoc value = getValue();
63             if (HiveMind.isNonBlank(value))
64                 writer.attribute("value", value);
65
66             String JavaDoc title = getTitle();
67             if (HiveMind.isNonBlank(title))
68                 writer.attribute("title", title);
69
70             boolean multiple = isMultiple();
71             if (multiple)
72                 writer.attribute("multiple", multiple);
73
74             renderInformalParameters(writer, cycle);
75         }
76
77         renderBody(writer, cycle);
78
79         if (render)
80         {
81             writer.end();
82         }
83
84         cycle.removeAttribute(ATTRIBUTE_NAME);
85     }
86
87     public abstract boolean isMultiple();
88
89     public abstract String JavaDoc getName();
90
91     public abstract String JavaDoc getValue();
92
93     public abstract String JavaDoc getTitle();
94 }
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