Remove few html tag from the html dom

I have below html table. I want to convert it to xml. I have done my coding as below whereby this will convert to html dom first and later i will convert it to xml. My problem is i just want to remain the <th>, <tr> <tbody>,<table> and <p> tag the rest of the tag should not be captured in the document How can i do that? As i would like to change the html table to xml table. So after that i will able to proceed to use list to insert the data to a class which will then be converted ot xml.

builder = factory.newDocumentBuilder();		
is = new InputSource(new StringReader(tableInString));
document = builder.parse(is);
document.getDocumentElement().normalize();

<table style="width: 100%;">
    <colgroup>
        <col style="width: 20%;"/>
        <col style="width: 20%;"/>
        <col style="width: 50%;"/>
        <col style="width: 10%;"/>
    </colgroup>
    <tbody>
        <tr>
            <th colspan="1">
                <p>Header1</p>
            </th>
            <th colspan="2">
                <span><div>Header2</div></span>
            </th>
            <th colspan="1">
                p><a><strong>Header3</strong></a></p>
            </th>
        </tr>
        <tr>
            <td colspan="1">
                <div>Value1</div>
            </td>
            <td colspan="2">
                <span><div>Value2</div></span>
            </td>
            <td colspan="1">
                <p><a><strong>Value3</strong></a></p>
            </td>
        </tr>
    </tbody>
</table>