How to unescape tags without unescaping content

Question

How can I unescape only the tags but not the content? Let me explain on an example...

This is the original raw response:

<GetWhoISResponse xmlns="http://www.webservicex.net">
         <GetWhoISResult>Whois Server Version 2.0

To single out one record, look it up with "xxx", where xxx is one of the
of the records displayed above. If the records are the same, look them up
with "=xxx" to receive a full display for each record.

>>> Last update of whois database: Mon, 30 Dec 2013 08:20:00 UTC <<<

NOTICE: The expiration date displayed in this record is the date the 
registrar's sponsorship of the domain name registration in the registry is 
currently set to expire. This date does not necessarily reflect the expiration 
date of the domain name registrant's agreement with the sponsoring 
registrar.  Users may consult the sponsoring registrar's Whois database to 
view the registrar's reported date of expiration for this registration.

</GetWhoISResult>
      </GetWhoISResponse>

If I use StringEscapeUtils and unescape text (unescapeXml):

<GetWhoISResponse xmlns="http://www.webservicex.net">
    <GetWhoISResult>Whois Server Version 2.0

To single out one record, look it up with "xxx", where xxx is one of the
of the records displayed above. If the records are the same, look them up
with "=xxx" to receive a full display for each record.

>>> Last update of whois database: Mon, 30 Dec 2013 08:20:00 UTC <<<

NOTICE: The expiration date displayed in this record is the date the 
registrar's sponsorship of the domain name registration in the registry is 
currently set to expire. This date does not necessarily reflect the expiration 
date of the domain name registrant's agreement with the sponsoring 
registrar.  Users may consult the sponsoring registrar's Whois database to 
view the registrar's reported date of expiration for this registration.

    </GetWhoISResult>
</GetWhoISResponse>

The problem is in the middle, in the line where < and > are escaped. I need this, because I would like to convert this to JSON, but now I get parsing error.

Answer 1

It is an interesting problem and I tried using forgiving xml parsers but they don't seem to parse a broken xml. The next best bet was regex and I managed to parse the given xml through it with a big caveat that the lesser and greater signs should not form a pattern of a tag, like:

< some random text here and >

After some research I finalized the 2 regex patterns for the given xml (can be used in a generalized format too):

public static final String LESSER_STRING = "<(.[^>]*)(<)+";
public static final String GREATER_STRING = ">[^<](.[^<]*)(>)+";

These strings are used to establish the regex pattern for the matcher to scan through the sequences.

Here is the working code with the output:

public static final String LESSER_STRING = "<(.[^>]*)(<)+";
    public static final String GREATER_STRING = ">[^<](.[^<]*)(>)+";
    public static final String ESCAPED_XML = "&lt;GetWhoISResponse xmlns=&quot;http://www.webservicex.net&quot;&gt;&lt;GetWhoISResult&gt;Whois Server Version 2.0 To single out one record, look it up with &quot;xxx&quot;, where xxx is one of the of the records displayed above. If the records are the same, look them up with &quot;=xxx&quot; to receive a full display for each record. &gt;&gt;&gt; Last update of whois database: Mon, 30 Dec 2013 08:20:00 UTC &lt;&lt;&lt; NOTICE: The expiration date displayed in this record is the date the registrar&apos;s sponsorship of the domain name registration in the registry is currently set to expire. This date does not necessarily reflect the expiration date of the domain name registrant&apos;s agreement with the sponsoring registrar.  Users may consult the sponsoring registrar&apos;s Whois database to view the registrar&apos;s reported date of expiration for this registration.&lt;/GetWhoISResult&gt;&lt;/GetWhoISResponse&gt;";
    private static Matcher matcher;
    private static Pattern pattern;
    private static String alter;
    private static StringBuffer str = new StringBuffer();
    private static StringBuffer jsonString = new StringBuffer();

    public static void main(String[] args) {
        String xml = StringEscapeUtils.unescapeXml(ESCAPED_XML);

        pattern = Pattern.compile(GREATER_STRING);
        matcher = pattern.matcher(xml);

        while (matcher.find()) {
            System.out.println(matcher.group(0));
            System.out.println(matcher.group(0).substring(1));

            // Find the first encountered greater than sing assuming greater
            // than and less than do not form a 'tag' pattern

            // Picks the first value after the 'last opened tag' including the
            // greater sign - take substring 1
            alter = ">" + matcher.group(0).substring(1).replaceAll(">", "&gt;");
            matcher.appendReplacement(str, alter);
        }

        matcher.appendTail(str);

        pattern = Pattern.compile(LESSER_STRING);
        matcher = pattern.matcher(str);

        while (matcher.find()) {
            System.out.println(matcher.group(0));
            System.out.println(matcher.group(0).substring(0,
                    matcher.group(0).length() - 1));

            // Find the encountered lesser than sign assuming greater
            // than and less than do not form a 'tag' pattern

            // Picks the content between the lesser tags and the last opened
            // tag; including the lesser sign of the tag
            // Reduce it by 1 to prevent the last tag getting replaced
            alter = matcher.group(0)
                    .substring(0, matcher.group(0).length() - 1);

            // Add the last tag as is without replacing
            alter = alter.replaceAll("<", "&lt;") + "<";
            matcher.appendReplacement(jsonString, alter);

        }

        matcher.appendTail(jsonString);

        System.out.println(jsonString);
    }

Output:

<GetWhoISResponse xmlns="http://www.webservicex.net"><GetWhoISResult>Whois Server Version 2.0 To single out one record, look it up with "xxx", where xxx is one of the of the records displayed above. If the records are the same, look them up with "=xxx" to receive a full display for each record. &gt;&gt;&gt; Last update of whois database: Mon, 30 Dec 2013 08:20:00 UTC &lt;&lt;&lt; NOTICE: The expiration date displayed in this record is the date the registrar's sponsorship of the domain name registration in the registry is currently set to expire. This date does not necessarily reflect the expiration date of the domain name registrant's agreement with the sponsoring registrar.  Users may consult the sponsoring registrar's Whois database to view the registrar's reported date of expiration for this registration.</GetWhoISResult></GetWhoISResponse>

Answer 2

you can read the content and replace the "<" and ">" again