详解Tomcat如何实现Comet

public interface CometProcessor extends Servlet{
  public void event(CometEvent event)
    throws IOException, ServletException;
}

public class CometServlet extends HttpServlet implements CometProcessor {

  protected ArrayList connections = new ArrayList();

  public void event(CometEvent event) throws IOException, ServletException {
    HttpServletRequest request = event.getHttpServletRequest();
    HttpServletResponse response = event.getHttpServletResponse();
    if (event.getEventType() == CometEvent.EventType.BEGIN) {
      synchronized (connections) {
        connections.add(response);
      }
    } else if (event.getEventType() == CometEvent.EventType.ERROR) {
      synchronized (connections) {
        connections.remove(response);
      }
    }else if (event.getEventType() == CometEvent.EventType.END) {
      synchronized (connections) {
        connections.remove(response);
      }
    } else if (event.getEventType() == CometEvent.EventType.READ) {
      InputStream is = request.getInputStream();
      byte[] buf = new byte[512];
      do {
        int n = is.read(buf);
        if (n > 0) {
          System.out.println(new String(buf, 0, n));
        } else if (n < 0) {
          return;
        }
      } while (is.available() > 0);
    }
  }
}