Controlling namespace prefixes in JAXB

Question

How does jaxb determine the list of namespace prefix declarations whem marshalling an object? I used xjc to compile java classes for ebics (ebics schema). When I create an i

Answer 1

After crawling many posts, solutions using NamespacePrefixMapper has dependency on JDK version (which may break the code in the future) or the XML DOM tree manipulation looks complicated.

My brute-force approach is to manipulate the generated XML itself.

/**
 * Utility method to hide unused xmlns definition in XML root.
 * @param sXML Original XML string.
 * @return
 */
public static String hideUnUsedNamespace(String sXML) {
    int iLoc0 = sXML.indexOf("?><");
    int iLoc1 = sXML.indexOf("><",iLoc0+3)+1;
    String sBegin = sXML.substring(0,iLoc0+2);
    String sHeader = sXML.substring(iLoc0+2, iLoc1-1);
    String sRest = sXML.substring(iLoc1);
    //System.out.println("sBegin=" + sBegin);
    //System.out.println("sHeader=" + sHeader);
    //System.out.println("sRest=" + sRest);

    String[] saNS = sHeader.split(" ");
    //System.out.println("saNS=" + java.util.Arrays.toString(saNS));

    StringBuffer sbHeader = new StringBuffer();
    for (String s: saNS) {
        //System.out.println(s);
        if (s.startsWith("xmlns:")) {
            String token = "<" + s.substring(6,s.indexOf("="));
            //System.out.println("token=" + token + ",indexOf(token)=" + sRest.indexOf(token));
            if (sRest.indexOf(token) >= 0) {
                sbHeader = sbHeader.append(s).append(" ");
                //System.out.println("...included");
            }
        } else {
            sbHeader = sbHeader.append(s).append(" ");
        }
    }
    return (sBegin + sbHeader.toString().trim() + ">" + sRest);
}

/**
 * Main method for testing
 */
public static void main(String[] args) {
    String sXML ="SIZBN001A5488F43223063171CA0FA59ADC635F02009-08-04T08:41:56.967ZEBICSEBIXEBICS-Kernel V2.0.4, SIZ/PPIFTBA037OZHNN......00001InitialisationCSbjPbiNcFqSl6lCI1weK5x1nMeCH5bTQq5pedq5uI0=...dFAYe281vj9NB7w+VoWIdfHnjY9hNbZLbHsDOu76QAE=......";

    System.out.println("Before=" + sXML);
    System.out.println("After =" + hideUnUsedNamespace(sXML));
}

The output shows un-used xmlns namespace is filtered out: