java - 如何扩展XMLStreamReader？

Question

http://docs.oracle.com/javaee/5/api/javax/xml/stream/XMLStreamReader.html

我想扩展 XMLStreamReader，但它是一个接口(interface)。

我想做这样的事情:

public class GraphDataStreamReader extends XMLStreamReader{

  public GraphDataStreamReader(){
    super();
  }

  public void nextStartElement() throws XMLStreamException {
    do {
      super.next();   
    } while (!super.isStartElement());
  }
}

其他类:

XMLInputFactory factory = XMLInputFactory.newInstance();
GraphDataStreamReader streamReader = (GraphDataStreamReader) factory.createXMLStreamReader(new FileReader(xmlFile)); //returns XMLStreamReader
streamReader.next(); //method from XMLStreamReader
streamReader.nextStartElement(); //method from GraphDataStreamReader

这可能吗？如果是，那么如何？

Answer 1

以下是如何扩展 StreamReaderDelegate :

class GraphDataStreamReader extends StreamReaderDelegate {
  public GraphDataStreamReader(XMLStreamReader reader) {
    super(reader);
  }

  public void nextStartElement() throws XMLStreamException {
    do {
      super.next();
    } while (!super.isStartElement());
  }
}

XMLInputFactory factory = XMLInputFactory.newInstance();
GraphDataStreamReader streamReader = new GraphDataStreamReader(
                                 factory.createXMLStreamReader(fileInputStream));
streamReader.next();
streamReader.nextStartElement();