HtmlUtil


1   package jodd.servlet;
2   
3   import jodd.util.StringUtil;
4   
5   /**
6    * Html utils for working with tag's names and attributes.
7    */
8   public class HtmlUtil {
9   
10      // ---------------------------------------------------------------- tag name
11  
12      /**
13       * Returns tag's name. Given string represents a HTML body of a tag,
14       * therefore it <b>must</b> start with '<'.
15       *
16       * @param tagBody tag's body
17       *
18       * @return tag's name, or <code>null</code> if tag not found
19       */
20      public static String getTagName(String tagBody) {
21          return getTagName(tagBody, 0);
22      }
23  
24      /**
25       * Returns tag's name. Given string represents a HTML body and given starting index
26       * <b>must</b> be the index of tag's start (i.e. '<').
27       * <p>
28       *
29       * Names of ending tags will always start with '/' character.
30       *
31       * @param body   hmtl body
32       * @param i      index of tag's start
33       *
34       * @return tag's name, or <code>null</code> if tag not found
35       */
36      public static String getTagName(String body, int i) {
37          if (body == null) {
38              return null;
39          }
40          if (body.charAt(i) != '<') {
41              return null;        // no tag
42          }
43          int start = i + 1;      // skip '<'
44          int len = body.length();
45          boolean isEndTag = false;
46          // skip all non-letters
47          while (start < len) {
48              char c = body.charAt(start);
49              if (c == '>') {
50                  return null;    // tag end found => name not found
51              }
52              if (c == '/') {     // this is an end tag
53                  start++;
54                  isEndTag = true;
55                  continue;
56              }
57              if (Character.isWhitespace(c) == false) {
58                  break;
59              }
60              start++;
61          }
62          if (start == len) {
63              return null;        // tag name not found
64          }
65          int end = start;
66          // skip all letters
67          while (end < len) {
68              char c = body.charAt(end);
69              if ((Character.isWhitespace(c) == true) || (c == '>')) {
70                  break;
71              }
72              end++;
73          }
74          if (end == len) {
75              return null;        // tag end not found
76          }
77  
78          String tagName = body.substring(start, end);
79          if (isEndTag == true) {
80              tagName = "/" + tagName;
81          }
82          return tagName;
83      }
84  
85  
86  
87      // ---------------------------------------------------------------- tag attribute
88  
89      /**
90       * Returns value of the first founded attribute that matches given name.
91       * It is assumed that given string represents tag's body.
92       * Note: attribute <b>must</b> end with the <code>="</code> or <code>='</code>.
93       * Attribute name is not case sensitive.
94       *
95       * @param tagBody  tag body
96       * @param attrName attribute name
97       *
98       * @return attribute value or <code>null</code> if attribute not found
99       */
100     public static String getAttribute(String tagBody, String attrName) {
101         return getAttribute(tagBody, attrName, 0);
102     }
103 
104     /**
105      * Returns value of the first founded attribute that matches given name.
106      * Given string may not be just a tag's body, however, start and end
107      * parameters must define tags body.
108      * Note: attribute <b>must</b> end with the <code>="</code> or <code>='</code>.
109      * Attribute name is not case sensitive.
110      *
111      * @param body     html body
112      * @param attrName attribute name
113      * @param start    index of tag's start
114      *
115      * @return attribute value or <code>null</code> if attribute not found
116      */
117     public static String getAttribute(String body, String attrName, int start) {
118         if (body == null) {
119             return null;
120         }
121         char quote = '\"';
122         int end = body.indexOf('>');
123         if (end == -1) {
124             return null;    // tag's end not found
125         }
126         int i = StringUtil.indexOfIgnoreCase(body, attrName + "=\"", start);
127         if ((i == -1) || (i > end)) {
128             i = StringUtil.indexOfIgnoreCase(body, attrName + "='", start);
129             if ((i == -1) || (i > end)) {
130                 return null;
131             }
132             quote = '\'';
133         }
134         String value = null;
135         i += attrName.length() + 2;
136         int s = i;
137         int j = -1;
138         while (true) {
139             j = body.indexOf(quote, s);
140             if (j == -1) {
141                 break;      // closed quation not found
142             }
143             if (body.charAt(j - 1) == '\\') {
144                 s = j + 1;
145                 continue;
146             } else {
147                 value = body.substring(i, j);
148                 break;
149             }
150         }
151         return value;
152     }
153 
154     // ---------------------------------------------------------------- add attribute & value
155 
156 
157     /**
158      * Adds attribute and its value to a tag. Attribute is added to the end of
159      * the tag, just before closing '>'. If name is not specified, nothing will
160      * be added. If value is not specified, it will be set to an empty string.
161      *
162      * @param tagBody tag body
163      * @param name    attribute name
164      * @param value   attribute value
165      *
166      * @return tag string with added attribute and value
167      */
168     public static String addAttribute(String tagBody, String name, String value) {
169         return addAttribute(tagBody, name, value, 0);
170     }
171 
172     /**
173      * Adds attribute and its value to a tag. Attribute is added to the end of
174      * the tag, just before closing '>'. If name is not specified, nothing will
175      * be added. If value is not specified, it will be set to an empty string.
176      *
177      * @param body   html body
178      * @param name   attribute name
179      * @param value  attribute value
180      * @param i      tag's offset in html body
181      *
182      * @return tag string with added attribute and value
183      */
184     public static String addAttribute(String body, String name, String value, int i) {
185         if (body == null) {
186             return null;
187         }
188         if (name == null) {
189             return body;
190         }
191         if (value == null) {
192             value = "";
193         }
194         int end = body.indexOf('>', i);
195         if (end == -1) {
196             return body;
197         }
198         StringBuffer result = new StringBuffer(body.length());
199         result.append(body.substring(i, end)).append(' ');
200         result.append(name).append('=').append('"');
201         //result.append(ServletUtil.encodeHtml(value)).append('"');
202         result.append(HtmlEncoder.encode(value)).append('"');
203         result.append(body.substring(end));
204         return result.toString();
205     }
206 
207 
208     // ---------------------------------------------------------------- add attribute, no value
209 
210 
211     /**
212      * Adds single attribute without value to a tag. Attribute is added to the
213      * end of the tag, just before closing '>'. If name is not specified, nothing
214      * will be added.
215      *
216      * @param tagBody tag body
217      * @param name    attribute name
218      *
219      * @return tag string with added attribute
220      */
221     public static String addAttribute(String tagBody, String name) {
222         return addAttribute(tagBody, name, 0);
223     }
224 
225     /**
226      * Adds single attribute without value to a tag. Attribute is added to the
227      * end of the tag, just before closing '>'. If name is not specified, nothing
228      * will be added.
229      *
230      * @param body   html body
231      * @param name   attribute name
232      * @param i      tag's offset in html body
233      *
234      * @return tag string with added attribute
235      */
236     public static String addAttribute(String body, String name, int i) {
237         if (body == null) {
238             return null;
239         }
240         if (name == null) {
241             return body;
242         }
243         int end = body.indexOf('>', i);
244         if (end == -1) {
245             return body;
246         }
247         StringBuffer result = new StringBuffer(body.length());
248         result.append(body.substring(i, end)).append(' ');
249         result.append(name).append(body.substring(end));
250         return result.toString();
251     }
252 
253 }
254
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