how to unescape XML in java

Question

I need to unescape a xml string containing escaped XML tags:

&lt;
&gt;
&amp;
etc...

I did find some libs that can perform this task, but i'd rather use a single method that can perform this task.

Can someone help?

cheers, Bas Hendriks

score 52 · Accepted Answer · edited May 26 '15 at 08:31

52

StringEscapeUtils.unescapeXml(xml)

(commons-lang, download)

edited May 26 '15 at 08:31

turbanoff

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answered May 14 '10 at 12:11

Bozho

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2

"but i'd rather use a single method that can perform this task." – Bas Hendriks May 14 '10 at 12:19
1

Bas, read commons-lang's source code and see if it's worth to reinvent the wheel in your case instead of justing using it. – Felipe Cypriano May 14 '10 at 12:39
1

@Bas - there's nothing in the standard Java library to do this, so either you use a third-party library that can do this for you, or you have to write it yourself (not recommended). – Jesper May 14 '10 at 14:12
7

commons-lang seems deprecated, and commons-text should be used. http://commons.apache.org/proper/commons-text https://mvnrepository.com/artifact/org.apache.commons/commons-text/1.6 – Kuro Mar 18 '19 at 18:10

texclayton · Answer 2 · 2012-03-08T17:44:45.823

Here's a simple method to unescape XML. It handles the predefined XML entities and decimal numerical entities (&#nnnn;). Modifying it to handle hex entities (&#xhhhh;) should be simple.

public static String unescapeXML( final String xml )
{
    Pattern xmlEntityRegex = Pattern.compile( "&(#?)([^;]+);" );
    //Unfortunately, Matcher requires a StringBuffer instead of a StringBuilder
    StringBuffer unescapedOutput = new StringBuffer( xml.length() );

    Matcher m = xmlEntityRegex.matcher( xml );
    Map<String,String> builtinEntities = null;
    String entity;
    String hashmark;
    String ent;
    int code;
    while ( m.find() ) {
        ent = m.group(2);
        hashmark = m.group(1);
        if ( (hashmark != null) && (hashmark.length() > 0) ) {
            code = Integer.parseInt( ent );
            entity = Character.toString( (char) code );
        } else {
            //must be a non-numerical entity
            if ( builtinEntities == null ) {
                builtinEntities = buildBuiltinXMLEntityMap();
            }
            entity = builtinEntities.get( ent );
            if ( entity == null ) {
                //not a known entity - ignore it
                entity = "&" + ent + ';';
            }
        }
        m.appendReplacement( unescapedOutput, entity );
    }
    m.appendTail( unescapedOutput );

    return unescapedOutput.toString();
}

private static Map<String,String> buildBuiltinXMLEntityMap()
{
    Map<String,String> entities = new HashMap<String,String>(10);
    entities.put( "lt", "<" );
    entities.put( "gt", ">" );
    entities.put( "amp", "&" );
    entities.put( "apos", "'" );
    entities.put( "quot", "\"" );
    return entities;
}

score 5 · Answer 3 · edited Sep 23 '15 at 06:19

Here is one that I wrote in ten minutes. It does not use regular expressions, only simple iterations. I do not think that this can be enhanced to be much faster.

public static String unescape(final String text) {
    StringBuilder result = new StringBuilder(text.length());
    int i = 0;
    int n = text.length();
    while (i < n) {
        char charAt = text.charAt(i);
        if (charAt != '&') {
            result.append(charAt);
            i++;
        } else {
            if (text.startsWith("&amp;", i)) {
                result.append('&');
                i += 5;
            } else if (text.startsWith("&apos;", i)) {
                result.append('\'');
                i += 6;
            } else if (text.startsWith("&quot;", i)) {
                result.append('"');
                i += 6;
            } else if (text.startsWith("&lt;", i)) {
                result.append('<');
                i += 4;
            } else if (text.startsWith("&gt;", i)) {
                result.append('>');
                i += 4;
            } else i++;
        }
    }
    return result.toString();
}

I like this simple approach. However it strips single ampersands from the input. The last `else` should IMHO be: `else { result.append(charAt); i++; }` — mvreijn, Dec 08 '21 at 11:18

score 0 · Answer 4 · answered Feb 03 '12 at 14:45

0

If you work with JSP, use su:unescapeXml from openutils-elfunctions

answered Feb 03 '12 at 14:45

msangel

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how to unescape XML in java

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