Span


1   /*
2    * Copyright 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   * $Header:$
17   */
18  package org.apache.beehive.netui.tags.html;
19  
20  import org.apache.beehive.netui.tags.HtmlUtils;
21  import org.apache.beehive.netui.tags.rendering.AbstractHtmlState;
22  import org.apache.beehive.netui.tags.rendering.SpanTag;
23  import org.apache.beehive.netui.tags.rendering.TagRenderingBase;
24  import org.apache.beehive.netui.tags.rendering.WriteRenderAppender;
25  import org.apache.beehive.netui.util.Bundle;
26  import org.apache.beehive.netui.util.logging.Logger;
27  
28  import javax.servlet.ServletRequest  ;
29  import javax.servlet.http.HttpServletRequest  ;
30  import javax.servlet.jsp.JspException  ;
31  
32  /**
33   * Generates styled text span based on an expression or literal value.
34   *
35   * <p>If the resulting value to be output is the <nobr>" "</nobr> String, it will output as
36   * the value <nobr><code>"&amp;nbsp;"</code></nobr>.</p>
37   * @jsptagref.tagdescription <p>Generates styled text based on a String literal or data binding expression.
38   *
39   * <p>The &lt;netui:span> tag is similar to the {@link Content} tag,
40   * except with respect to the way that it treats
41   * characters sensitive to HTML browsers.
42   * The &lt;netui:span> tag filters the input string for browser-sensitive characters
43   * and replaces these characters
44   * with the corresponding entity strings.  For example, if you pass the
45   * string '&amp;amp;' to a &lt;netui:span> tag, the string '&amp;amp;amp;' will be written to
46   * the HTML source file, and the following will be displayed
47   * in the browser: '&amp;amp;'.
48   *
49   * <p>The following table shows how the &lt;netui:span> and &lt;netui:content> tags treat HTML-sensitive characters.
50   * <blockquote>
51   * <table border="1">
52   * <tr>
53   * <td width="30%"><b>tag</b></td>
54   * <td width="30%"><b>generated HTML source</b></td>
55   * <td width="30%"><b>displayed in browser</b></td>
56   * </tr>
57   * <tr>
58   * <td>&lt;netui:content value="&amp;amp;"/></td>
59   * <td>&amp;amp;</td>
60   * <td>&</td>
61   * </tr>
62   * <tr>
63   * <td>&lt;netui:span value="&amp;amp;"/></td>
64   * <td>&amp;amp;amp;</td>
65   * <td>&amp;amp;</td>
66   * </tr>
67   * </table>
68   * </blockquote>
69   *
70   * <p><b>Note:</b> escaping is <i>not</i> applied to browser-sensitive characters in
71   * the <code>defaultValue</code> attribute.
72   * @example In this first sample, a &lt;netui:span> tag displays the Form Bean's firstName property.
73   * The &lt;netui:span> tag will resolve this data binding expression, and display its value.
74   *
75   * <pre>    &lt;netui:span value="${actionForm.firstName}" /></pre>
76   *
77   * <p>In this next sample, the <code>value</code> attribute will resolve to null.
78   * This causes the <code>defaultValue</code> to be displayed.  The user will see '&nbsp;'.</p>
79   * <pre>    &lt;netui:span value="${pageFlow.somethingNull}" defaultValue="&amp;nbsp;"/></pre>
80   *
81   * <p>In this next sample, the HTML will contain the text "&amp;amp;nbsp;" and the user will
82   * see '&amp;nbsp;'</p>
83   * <pre>    &lt;netui:span value="${pageFlow.somethingNull}" defaultValue="&amp;amp;nbsp;"/></pre>
84   * @netui:tag name="span" description="Places formatted or dynamically generated text on the page inside an HTML span."
85   */
86  public class Span extends LabelBase
87          implements IFormattable
88  {
89      private static final Logger logger = Logger.getInstance(Span.class);
90  
91      private SpanTag.State _state = new SpanTag.State();
92  
93      /**
94       * Return the name of the Tag.
95       */
96      public String   getTagName()
97      {
98          return "Label";
99      }
100 
101     /**
102      * This method will return the state associated with the tag.  This is used by this
103      * base class to access the individual state objects created by the tags.
104      * @return a subclass of the <code>AbstractHtmlState</code> class.
105      */
106     protected AbstractHtmlState getState()
107     {
108         return _state;
109     }
110 
111     /**
112      * Prepare the label formatters.
113      * @throws JspException if a JSP exception has occurred
114      */
115     public int doStartTag() throws JspException  
116     {
117         return EVAL_BODY_BUFFERED;
118     }
119 
120     /**
121      * Render the label.
122      * @throws JspException if a JSP exception has occurred
123      */
124     public int doEndTag() throws JspException  
125     {
126         boolean usingDefault = false;
127         boolean bypassEscape = false;
128 
129         String   scriptId = null;
130         ServletRequest   req = pageContext.getRequest();
131 
132         Object   labelObject = null;
133 
134         // if this is not client side binding, evalute the value
135         if (_value != null)
136             labelObject = _value;
137         else {
138             if (_defaultValue != null) {
139                 labelObject = _defaultValue;
140                 bypassEscape = HtmlUtils.containsEntity(_defaultValue.toString());
141             }
142             else {
143                 logger.warn(Bundle.getString("Tags_LabelExpressionNull", _value));
144                 labelObject = DEFAULT_NULL_TEXT;
145             }
146             usingDefault = true;
147         }
148 
149         // we assume that tagId will over have override id if both
150         // are defined.
151         if (_state.id != null) {
152             scriptId = renderNameAndId((HttpServletRequest  ) req, _state, null);
153         }
154 
155         // push the evaluated expression when we are not client side bound...
156         String   labelValue = (usingDefault && !_formatDefaultValue) ?
157                 labelObject.toString() : formatText(labelObject);
158 
159         // if there were errors in the formatters, report them.
160         if (_formatterErrors) {
161             if (bodyContent != null) {
162                 String   value = bodyContent.getString().trim();
163                 bodyContent.clearBody();
164                 write(value);
165             }
166         }
167 
168         if (hasErrors())
169             return reportAndExit(EVAL_PAGE);
170 
171         WriteRenderAppender writer = new WriteRenderAppender(pageContext);
172         TagRenderingBase br = TagRenderingBase.Factory.getRendering(TagRenderingBase.SPAN_TAG, req);
173         br.doStartTag(writer, _state);
174 
175         if (!bypassEscape)
176             filter(labelValue, writer, _escapeWhiteSpace);
177         else
178             write(labelValue);
179 
180         br.doEndTag(writer);
181 
182         if (scriptId != null)
183             write(scriptId);
184 
185         localRelease();
186         return EVAL_PAGE;
187     }
188 
189     /**
190      * Release any acquired resources.
191      */
192     protected void localRelease()
193     {
194         super.localRelease();
195         _state.clear();
196     }
197 }
198
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