001 package edu.nrao.sss.html;
002
003 import java.io.IOException;
004 import java.io.Writer;
005
006 import javax.swing.text.html.HTML;
007
008 /**
009 * An HTML anchor ({@link javax.swing.text.html.HTML.Tag#A}).
010 * <p>
011 * <b>Version Info:</b>
012 * <table style="margin-left:2em">
013 * <tr><td>$Revision: 1360 $</td></tr>
014 * <tr><td>$Date: 2008-06-19 14:08:48 -0600 (Thu, 19 Jun 2008) $</td></tr>
015 * <tr><td>$Author: dharland $</td></tr>
016 * </table></p>
017 *
018 * @author David M. Harland
019 * @since 2007-03-20
020 */
021 public class HtmlAnchor
022 extends HtmlElement
023 {
024 private String displayText;
025
026 /** Creates a new, unnamed, empty anchor. */
027 public HtmlAnchor()
028 {
029 this(null, null, null);
030 }
031
032 /**
033 * Creates a new HTML anchor with the given properties.
034 * The text form of this anchor is:<pre>
035 * <a name="<i>name</i>" href="<i>href</i>"><i>display</i></a>
036 * </pre>
037 *
038 * @param name the name of this anchor.
039 * If this parameter is <i>null</i>, this anchor will have
040 * no name.
041 *
042 * @param href the HTML link associated with this anchor.
043 * If this parameter is <i>null</i>, this anchor will have
044 * no link.
045 *
046 * @param display the text displayed on an HTML page for this anchor.
047 * If this parameter is <i>null</i>, it will be converted
048 * to the empty string (<tt>""</tt>).
049 */
050 public HtmlAnchor(String name, String href, String display)
051 {
052 super(HTML.Tag.A);
053
054 if (name != null)
055 attributes.put(HTML.Attribute.NAME,
056 new HtmlAttribute(HTML.Attribute.NAME, name));
057
058 if (href != null)
059 attributes.put(HTML.Attribute.HREF,
060 new HtmlAttribute(HTML.Attribute.HREF, href));
061
062 displayText = (display == null) ? "" : display;
063 }
064
065 /**
066 * Creates and returns a new HTML anchor by parsing {@code anchorTag}.
067 *
068 * @param anchorTag the HTML form of this anchor.
069 * The expected form of the text is:
070 * <pre> <a name="name" href='absolute or relative URL'>display text</a></pre>
071 * The anchor name can be "a" or "A"; you may even mix the capitalization in
072 * a single tag (<A ...>...</a>). Values may be quoted with
073 * either single (') or double (") quotes. Leading and trailing whitespace
074 * is permitted and will be trimmed during parsing.</p>
075 *
076 * @return a new HTML anchor by parsing {@code anchorTag}.
077 *
078 * @throws IllegalArgumentException if anything goes wrong during parsing.
079 */
080 public static HtmlAnchor parse(String anchorTag)
081 {
082 try
083 {
084 HtmlAnchor anchor = new HtmlAnchor();
085 anchor.parseAnchor(anchorTag);
086 return anchor;
087 }
088 catch (Exception ex)
089 {
090 throw new IllegalArgumentException("Could not parse anchorTag [" +
091 anchorTag + "]: " +
092 ex.getMessage());
093 }
094 }
095
096 @Override
097 public boolean isSimple()
098 {
099 return false;
100 }
101
102 /**
103 * Sets the text to display for this anchor.
104 *
105 * @param text the text to display for this anchor. If this
106 * parameter is <i>null</i>, it will be replaced by the
107 * empty string (<tt>""</tt>).
108 */
109 public void setDisplayText(String text)
110 {
111 displayText = (text == null) ? "" : text;
112 }
113
114 /**
115 * Returns the text to display for this anchor.
116 *
117 * @return the text to display for this anchor. This value is guaranteed
118 * to be non-null, but it could be the empty string (<tt>""</tt>).
119 */
120 public String getDisplayText()
121 {
122 return displayText;
123 }
124
125 /**
126 * Sets the value of this anchor tag based on the given text.
127 * <p>
128 * The expected form of the text is:
129 * <pre> <a name1="value1" name2='value two'>display text</a></pre>
130 * The anchor name can be "a" or "A"; you may even mix the capitalization in
131 * a single tag (<A ...>...</a>). Values may be quoted with
132 * either single (') or double (") quotes. Leading and trailing whitespace
133 * is permitted and will be trimmed during parsing.</p>
134 * <p>
135 * If anything goes wrong during parsing, an {@code IllegalArgumentException}
136 * is thrown. All successfully parsed information up to the point of the
137 * exception will be maintained by this instance.</p>
138 *
139 * @param anchorTag text representation of an HTML anchor.
140 */
141 private void parseAnchor(String anchorTag)
142 {
143 if (anchorTag == null)
144 throw new IllegalArgumentException("must not be null.");
145
146 String text = anchorTag.trim();
147
148 if (anchorTag.length() == 0)
149 throw new IllegalArgumentException("must not be empty.");
150
151 if (!(text.startsWith("<a") || text.startsWith("<A")) ||
152 !(text.endsWith("</a>") || text.endsWith("</A>")))
153 throw new IllegalArgumentException(
154 "must start with '<a' and end with '</a>'.");
155
156 int endOpenTagPos = text.indexOf('>');
157
158 displayText = text.substring(endOpenTagPos+1,text.indexOf("</"));
159
160 parseAttributes(text.substring(2, endOpenTagPos));
161 }
162
163 //============================================================================
164 // WRITING
165 //============================================================================
166
167 void writeContentsAsHtml(Writer device, int padding, int depth) throws IOException
168 {
169 device.write(displayText);
170 }
171
172 //============================================================================
173 // CONVENIENCE METHODS
174 //============================================================================
175
176 /**
177 * Returns <i>true</i> if this anchor has a non-<i>null</i> value for the
178 * <tt>HTML.Attribute.NAME</tt> type.
179 *
180 * @return
181 * <i>true</i> if this anchor has a non-<i>null</i> name.
182 */
183 public boolean hasName()
184 {
185 return getAttributeValue(HTML.Attribute.NAME) != null;
186 }
187
188 /**
189 * Returns the name of this anchor, if any. If this anchor has no name,
190 * <i>null</i> is returned. This is a convenience method equivalent to
191 * the call <tt>getAttributeValue(HTML.Attribute.NAME)</tt>.
192 *
193 * @return
194 * the name of this anchor, or <i>null</i> if this anchor has no name.
195 */
196 public String getName()
197 {
198 return getAttributeValue(HTML.Attribute.NAME);
199 }
200
201 /**
202 * Return <i>true</i> if this anchor has a non-<i>null</i> value for the
203 * <tt>HTML.Attribute.HREF</tt> type.
204 *
205 * @return
206 * <i>true</i> if this anchor has a non-<i>null</i> name.
207 */
208 public boolean hasUrlText()
209 {
210 return getAttributeValue(HTML.Attribute.HREF) != null;
211 }
212
213 /**
214 * Returns the <tt>HREF</tt> value for this anchor, if any.
215 * If this anchor has no such value, <i>null</i> is returned.
216 * This is a convenience method equivalent to the call
217 * <tt>getAttributeValue(HTML.Attribute.NAME)</tt>.
218 * Beware that the text returned may be only a <i>relative</i>
219 * URL, not the entire URL.
220 *
221 * @return
222 * the href value of this anchor,
223 * or <i>null</i> if this anchor has no such value.
224 */
225 public String getUrlText()
226 {
227 return getAttributeValue(HTML.Attribute.HREF);
228 }
229
230 //============================================================================
231 //
232 //============================================================================
233
234 /*
235 public static void main(String[] args)
236 {
237 HtmlAnchor anchor = HtmlAnchor.parse(args[0]);
238
239 for (String key : anchor.attributes.keySet())
240 {
241 System.out.println("["+key + "=" + anchor.attributes.get(key) + "]");
242 }
243 System.out.println("Display text [" + anchor.displayText + "]");
244 System.out.println(anchor.appendTo(null).toString());
245 System.out.println(HTML.getAttributeKey("class").toString());
246 System.out.println(HTML.NULL_ATTRIBUTE_VALUE + ", " + HTML.NULL_ATTRIBUTE_VALUE.length());
247 }
248 */
249 }