An encoder for converting text to be used within XML attribute values : DOM Attribute « XML « Java Tutorial

1. Java Tutorial
2. XML
3. DOM Attribute

import java.text.CharacterIterator;
import java.text.StringCharacterIterator;
import java.util.HashMap;
import java.util.Map;

/**
 * An encoder useful for converting text to be used within XML attribute values.
 * The following translations will be performed:
 * <table cellspacing="0" cellpadding="1" border="1">
 * <tr>
 * <th>Raw (Unencoded)<br/>Character</th>
 * <th>Translated (Encoded)<br/>Entity</th>
 * </tr>
 * <tr>
 * <td> &amp; </td>
 * <td> &amp;amp; </td>
 * </tr>
 * <tr>
 * <td> &lt; </td>
 * <td> &amp;lt; </td>
 * </tr>
 * <tr>
 * <td> &gt; </td>
 * <td> &amp;gt; </td>
 * </tr>
 * <tr>
 * <td> &quot; </td>
 * <td> &amp;quot; </td>
 * </tr>
 * <tr>
 * <td> &#039; </td>
 * <td> &amp;#039; </td>
 * </tr>
 * <tr>
 * <td>All Others</td>
 * <td>No Translation</td>
 * </tr>
 * </table>
 * </p>
 */
public class XmlValueEncoder  {
    
    private static final Map<String, Character> SPECIAL_ENTITIES;
    
    static {
        SPECIAL_ENTITIES = new HashMap<String, Character>();
        
        SPECIAL_ENTITIES.put("quot", '"');
        SPECIAL_ENTITIES.put("gt", '>');
        SPECIAL_ENTITIES.put("lt", '<');
        SPECIAL_ENTITIES.put("amp", '&');
        
    }
    
    /**
     * {@inheritDoc}
     *
     * @see org.jboss.dna.common.text.TextEncoder#encode(java.lang.String)
     */
    public String encode( String text ) {
        if (text == null) return null;
        StringBuilder sb = new StringBuilder();
        CharacterIterator iter = new StringCharacterIterator(text);
        for (char c = iter.first(); c != CharacterIterator.DONE; c = iter.next()) {
            switch (c) {
                case '&':
                    sb.append("&amp;");
                    break;
                case '"':
                    sb.append("&quot;");
                    break;
                case '<':
                    sb.append("&lt;");
                    break;
                case '>':
                    sb.append("&gt;");
                    break;
                case '\'':
                    sb.append("&#039;");
                    break;
                default:
                    sb.append(c);
            }
        }
        return sb.toString();
    }

    /**
     * {@inheritDoc}
     *
     * @see org.jboss.dna.common.text.TextDecoder#decode(java.lang.String)
     */
    public String decode( String encodedText ) {
        if (encodedText == null) return null;
        StringBuilder sb = new StringBuilder();
        CharacterIterator iter = new StringCharacterIterator(encodedText);
        for (char c = iter.first(); c != CharacterIterator.DONE; c = iter.next()) {
            if (c == '&') {
                int index = iter.getIndex();
                
                do {
                    c = iter.next();
                }
                while (c != CharacterIterator.DONE && c != ';');

                // We found a closing semicolon
                if (c == ';') {
                    String s = encodedText.substring(index + 1, iter.getIndex());
                    
                    if (SPECIAL_ENTITIES.containsKey(s)) {
                        sb.append(SPECIAL_ENTITIES.get(s));
                        continue;
                        
                    }
                    
                    if (s.length() > 0 && s.charAt(0) == '#') {
                        try {
                            sb.append((char) Short.parseShort(s.substring(1, s.length())));
                            continue;
                        }
                        catch (NumberFormatException nfe) {
                            // This is possible in malformed encodings, but let it fall through
                        }
                    }
                }
                
                // Malformed encoding, restore state and pass poorly encoded data back
                c = '&';
                iter.setIndex(index);                            
            }

            sb.append(c);

        }
        return sb.toString();
    }
}