Cannot read <post_body> tag from a XML file

I asked yersterday this question. Now I am having problem with the similar XML file. My problems that it reads all good, until "post_body". It does find it when tetsing in starElement, but cannot print the context of this tag.

Why is that ? I also been adviced to print s in endDocument() but seems that doesnt work. Here is my XML file again and code:

<?xml version="1.0" encoding="UTF-8"?>
<root>
   <data>
      <track clipid="1">
         <url>http://www.emp3world.com/to_download.php?id=33254</url>
         <http_method>GET or POST</http_method>
         <post_body>a=1&b=2&c=3</post_body>
      </track>
   </data>
</root>

Code:

class MyHandler extends DefaultHandler
{
    String str = "";
    StringBuil开发者_如何学编程der s = new StringBuilder();
    public void startElement(String namespaceURI, String sName, String qName, Attributes atts)
    {

        s.setLength(0);

        if(qName.equals("track"))
        {
            s.append("ID: ").append(atts.getValue("clipid")).append("\n");
        }
        if(qName.equals("url"))
        {
            s.append("URL: ");
        }
        if(qName.equals("http_method"))
        {
            s.append("Http method: ");
        }
        if(qName.equals("header"))
        {
            s.append("Header: ");
        }
        if(qName.equals("post_body"))
        {
            s.append("Post body: ");
        }
    }

    public void endElement(String uri, String localName, String qName)
    {
        System.out.println(s);
    }

    public void characters(char[] ch, int start, int length) throws SAXException {
        s.append(new String(ch, start, length));
    }
}

This is not valid XML:

<post_body>a=1&b=2&c=3</post_body>

The & symbols are not properly encoded, so this file is malformed and invalid, and XML parsers will not read it.

It should be

<post_body>a=1&amp;b=2&amp;c=3</post_body>