ServiceResolver.java :  » Client » daap-client » javax » jmdns » impl » tasks » Android Open Source

// Copyright 2003-2005 Arthur van Hoff, Rick Blair
// Licensed under Apache License version 2.0
// Original license LGPL
package javax.jmdns.impl.tasks;

import java.io.IOException;
import java.util.Iterator;
import java.util.Timer;
import java.util.TimerTask;

import javax.jmdns.impl.DNSConstants;
import javax.jmdns.impl.DNSOutgoing;
import javax.jmdns.impl.DNSQuestion;
import javax.jmdns.impl.DNSRecord;
import javax.jmdns.impl.DNSState;
import javax.jmdns.impl.JmDNSImpl;
import javax.jmdns.impl.ServiceInfoImpl;

/** The ServiceResolver queries three times consecutively for services of a given
 * type, and then removes itself from the timer.
 * <p/>
 * The ServiceResolver will run only if JmDNS is in state ANNOUNCED. REMIND:
 * Prevent having multiple service resolvers for the same type in the timer
 * queue. */
public class ServiceResolver extends TimerTask {
  /**
     * 
     */
  private final JmDNSImpl jmDNSImpl;
  /** Counts the number of queries being sent. */
  int count = 0;
  private String type;

  public ServiceResolver(JmDNSImpl jmDNSImpl, String type) {
    this.jmDNSImpl = jmDNSImpl;
    this.type = type;
  }

  public void start(Timer timer) {
    timer.schedule(this, DNSConstants.QUERY_WAIT_INTERVAL,
        DNSConstants.QUERY_WAIT_INTERVAL);
  }

  @SuppressWarnings("rawtypes")
  public void run() {
    try {
      if (this.jmDNSImpl.getState() == DNSState.ANNOUNCED) {
        if (count++ < 3) {
          long now = System.currentTimeMillis();
          DNSOutgoing out = new DNSOutgoing(
              DNSConstants.FLAGS_QR_QUERY);
          out.addQuestion(new DNSQuestion(type,
              DNSConstants.TYPE_PTR, DNSConstants.CLASS_IN));
          for (Iterator s = this.jmDNSImpl.getServices().values()
              .iterator(); s.hasNext();) {
            final ServiceInfoImpl info = (ServiceInfoImpl) s.next();
            try {
              out.addAnswer(
                  new DNSRecord.Pointer(info.getType(),
                      DNSConstants.TYPE_PTR,
                      DNSConstants.CLASS_IN,
                      DNSConstants.DNS_TTL, info
                          .getQualifiedName()), now);
            } catch (IOException ee) {
              break;
            }
          }
          this.jmDNSImpl.send(out);
        } else {
          // After three queries, we can quit.
          this.cancel();
        }
      } else {
        if (this.jmDNSImpl.getState() == DNSState.CANCELED) {
          this.cancel();
        }
      }
    } catch (Throwable e) {
      this.jmDNSImpl.recover();
    }
  }
}