XMLUtils


1   /* *****************************************************************************
2    * XMLUtils.java
3    * ****************************************************************************/
4   
5   /* J_LZ_COPYRIGHT_BEGIN *******************************************************
6   * Copyright 2001-2004 Laszlo Systems, Inc.  All Rights Reserved.              *
7   * Use is subject to license terms.                                            *
8   * J_LZ_COPYRIGHT_END *********************************************************/
9   
10  package org.openlaszlo.xml.internal;
11  import org.openlaszlo.utils.ChainedException;
12  import org.jdom.Document;
13  import org.jdom.Element;
14  import org.xml.sax.SAXException  ;
15  import java.io.*;
16  import java.util.*;
17  
18  /**
19   * XMLUtils
20   *
21   * @author Oliver Steele
22   */
23  abstract public class XMLUtils {
24      /** Returns an element's attribute value, as a String.  Same as
25       * Element.getAttributeValue, except that it takes a default value
26       * to return if the attribute is missing.
27       *
28       * @param e an Element
29       * @param aname the attribute name
30       * @param defaultValue default value
31       * @return a String
32       */
33      public static String   getAttributeValue(Element e, String   aname,
34                                             String   defaultValue)
35      {
36          String   value = e.getAttributeValue(aname);
37          if (value == null) {
38              value = defaultValue;
39          }
40          return value;
41      }
42  
43      /** Returns an element's attribute value, as a String.  Same as
44       * Element.getAttributeValue, except guarantees not to return
45       * void.
46       *
47       * @param e an Element
48       * @param aname the attribute name
49       * @return a String
50       */
51      public static String   requireAttributeValue(Element e, String   aname) {
52          String   value = e.getAttributeValue(aname);
53          if (value == null) {
54              throw new MissingAttributeException(e, aname);
55          }
56          return value;
57      }
58      
59      /**
60       * Escape the 5 entities defined by XML. 
61       * These are: '<', '>', '\', '&', '"'.
62       * 
63       * @param s an xml string
64       * @return an escaped xml string
65       */
66      public static String   escapeXml(String   s) {
67          if (s == null) return null;
68          StringBuffer   sb = new StringBuffer  ();
69          for(int i=0; i<s.length(); i++) {
70              char c = s.charAt(i);
71              if (c == '<') {
72                  sb.append("&lt;");
73              } else if (c == '>') {
74                  sb.append("&gt;");
75              } else if (c == '\'') {
76                  sb.append("&apos;");
77              } else if (c == '&') {
78                  sb.append("&amp;");
79              } else if (c == '"') {
80                  sb.append("&quot;");
81              } else {
82                  sb.append(c);
83              }
84          }
85          return sb.toString();
86      }
87  
88      /**
89       * Escape 3 entities understood by HTML text.
90       * These are: '<', '>', '&'
91       * 
92       * TODO: [2003-05-05 bloch] move to LZHttpUtils and rename
93       * to escapeHTML
94       *
95       * @param s an xml string
96       * @return an escaped xml string
97       */
98      public static String   escapeXmlForSWFHTML(String   s) {
99          if (s == null) return null;
100         StringBuffer   sb = new StringBuffer  ();
101         for(int i=0; i<s.length(); i++) {
102             char c = s.charAt(i);
103             if (c == '<') {
104                 sb.append("&lt;");
105             } else if (c == '>') {
106                 sb.append("&gt;");
107             } else if (c == '&') {
108                 sb.append("&amp;");
109             } else {
110                 sb.append(c);
111             }
112         }
113         return sb.toString();
114     }
115 
116     /**
117      * Make sure all the following sequences
118      *    &lt; &gt; &apos; &quot; and &amp;
119      *
120      *    have their ampersands escaped
121      * 
122      * @param s an xml string
123      * @return an escaped xml string
124      */
125     public static String   escapeAmpersands(String   s) {
126         if (s == null) return null;
127         StringBuffer   sb = new StringBuffer  ();
128         for(int i=0; i<s.length(); i++) {
129             char c = s.charAt(i);
130             if (c == '&') {
131                 int j = i+1;
132                 if (s.regionMatches(j, "lt;", 0, 3)) {
133                     sb.append("&amp;lt;"); 
134                     i += 3;
135                 } else if (s.regionMatches(j, "gt;", 0, 3)) {
136                     sb.append("&amp;gt;");
137                     i += 3;
138                 } else if (s.regionMatches(j, "apos;", 0, 5)) {
139                     sb.append("&amp;apos;");
140                     i += 5;
141                 } else if (s.regionMatches(j, "quot;", 0, 5)) {
142                     sb.append("&amp;quot;");
143                     i += 5;
144                 } else if (s.regionMatches(j, "amp;", 0, 4)) {
145                     sb.append("&amp;amp;");
146                     i += 4;
147                 } else {
148                     sb.append(c);
149                 }
150             } else {
151                 sb.append(c);
152             }
153         }
154 
155         return sb.toString();
156     }
157 
158     public static boolean isURL(String   str) {
159         // when running in ant, some of these protocols (https and soap, at
160         // least) throw MalformedURLException
161         if (str.startsWith("http:") ||
162             str.startsWith("https:") ||
163             str.startsWith("file:") ||
164             str.startsWith("ftp:") ||
165             str.startsWith("soap:")) {
166             return true;
167         }
168         try {
169             new java.net.URL  (str); // for effect
170             return true;
171         } catch (java.net.MalformedURLException   e) {
172             return false;
173         }
174     }
175 
176     public static Element parse(String   source) {
177         try {
178             org.jdom.input.SAXHandler handler = new org.jdom.input.SAXHandler();
179             org.xml.sax.XMLReader   reader =
180                 org.xml.sax.helpers.XMLReaderFactory.createXMLReader(
181                     "org.apache.xerces.parsers.SAXParser");
182             reader.setContentHandler(handler);
183             reader.parse(new org.xml.sax.InputSource  (new StringReader(source)));
184             Document doc = handler.getDocument();
185             return doc.getRootElement();
186         } catch (IOException e) {
187             throw new ChainedException(e);
188         } catch (SAXException   e) {
189             throw new ChainedException(e);
190         }
191     }
192 
193     /** 
194      * Returns xml from first non-declaration element.
195      *
196      * @param xml xml string buffer.
197      * @return xml string with no declarations.
198      */
199     public static String   getNoDeclarationXML(StringBuffer   xml)
200     {
201         int len = xml.length();
202         for (int i=0; i < len; i++) 
203             if ( xml.charAt(i) == '<' && ( i+1 < len) ) 
204                 if (xml.charAt(i+1) != '?' && xml.charAt(i+1) != '!')
205                     return xml.substring(i);
206         return xml.toString();
207     }
208 
209 
210     public static String   toString(Element element) {
211         org.jdom.output.XMLOutputter outputter =
212             new org.jdom.output.XMLOutputter();
213         outputter.setTextNormalize(true);
214         return outputter.outputString(element);
215     }    
216 
217     /**
218      * Helper function for getXPathTo
219      */
220     private static StringBuffer   getXPathToInternal(Element elt) {
221         Element parent = elt.getParent();
222         if (parent == null) {
223             return new StringBuffer  ("/*[1]");
224         }
225         int i = parent.getChildren().indexOf(elt);
226         if (i == -1) {
227             throw new RuntimeException  ("Element " + elt + " not in parent " + parent + " .getChildren()?");
228         }
229         StringBuffer   sb = getXPathToInternal(parent);
230         sb.append("/*[");
231         // DOM is 1-based
232         sb.append(i + 1);
233         sb.append("]");
234         return sb;
235     }
236 
237     /**
238      * Returns an xpath for the element
239      *
240      * @param elt the element
241      * @return the xpath
242      */
243     public static String   getXPathTo(Element elt) {
244         return getXPathToInternal(elt).toString();
245     }
246 }
247
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