问org.apache.harmony.xml.ExpatParser$ParseException的问题

EN

org.apache.harmony.xml.ExpatParser$ParseException: At line 1, column 0: no element found

public abstract class BaseFeedParser{

    private final URL url;
    private InputStream is;

    protected BaseFeedParser(String url) {
        try {
            this.url = new URL(url);
        } catch (MalformedURLException e) {
            throw new RuntimeException(e);
        }
    }

    protected InputStream getInputStream() {
        try {
            this.is = url.openConnection().getInputStream();
            return is;
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    protected void closeInputStream() throws IOException{
        if(this.is!=null)
            this.is.close();
    }
}

public class Parser extends BaseFeedParser {

    public void parse() {
        RootElement root = new RootElement("xml");
        //additional 
        Element child = root.getChild("child");
        child.setStartElementListener(new StartElementListener() {          
            @Override
            public void start(Attributes attributes) {
                // do something....
            }
        });

        try {
            Xml.parse(this.getInputStream(), Xml.Encoding.UTF_8, root
                .getContentHandler());

            closeInputStream();

        } catch (Exception e) {
            throw new RuntimeException(e);
        }   
    }
}