Exemplo n.º 1
0
  public void fun(URLConnection connection) {
    try {
      connection.connect();
      // print header fields

      Map<String, List<String>> headers = connection.getHeaderFields();
      for (Map.Entry<String, List<String>> entry : headers.entrySet()) {
        String key = entry.getKey();
        for (String value : entry.getValue()) System.out.println(key + ": " + value);
      }

      // print convenience functions

      System.out.println("----------");
      System.out.println("getContentType: " + connection.getContentType());
      System.out.println("getContentLength: " + connection.getContentLength());
      System.out.println("getContentEncoding: " + connection.getContentEncoding());
      System.out.println("getDate: " + connection.getDate());
      System.out.println("getExpiration: " + connection.getExpiration());
      System.out.println("getLastModifed: " + connection.getLastModified());
      System.out.println("----------");

      Scanner in = new Scanner(connection.getInputStream());

      // print first ten lines of contents

      for (int n = 1; in.hasNextLine() && n <= 10; n++) System.out.println(in.nextLine());
      if (in.hasNextLine()) System.out.println(". . .");
    } catch (IOException e) {
      e.printStackTrace();
    }
  }
  /**
   * Determine if a host is reachable by attempting to resolve the host name, and then attempting to
   * open a connection.
   *
   * @param hostName Name of the host to connect to.
   * @return {@code true} if a the host is reachable, {@code false} if the host name cannot be
   *     resolved, or if opening a connection to the host fails.
   */
  protected static boolean isHostReachable(String hostName) {
    try {
      // Assume host is unreachable if we can't get its dns entry without getting an exception
      //noinspection ResultOfMethodCallIgnored
      InetAddress.getByName(hostName);
    } catch (UnknownHostException e) {
      String message = Logging.getMessage("NetworkStatus.UnreachableTestHost", hostName);
      Logging.verbose(message);
      return false;
    } catch (Exception e) {
      String message = Logging.getMessage("NetworkStatus.ExceptionTestingHost", hostName);
      Logging.verbose(message);
      return false;
    }

    // Was able to get internet address, but host still might not be reachable because the address
    // might have been
    // cached earlier when it was available. So need to try something else.

    URLConnection connection = null;
    try {
      URL url = new URL("http://" + hostName);
      Proxy proxy = WWIO.configureProxy();
      if (proxy != null) connection = url.openConnection(proxy);
      else connection = url.openConnection();

      connection.setConnectTimeout(2000);
      connection.setReadTimeout(2000);
      String ct = connection.getContentType();
      if (ct != null) return true;
    } catch (IOException e) {
      String message = Logging.getMessage("NetworkStatus.ExceptionTestingHost", hostName);
      Logging.info(message);
    } finally {
      if (connection instanceof HttpURLConnection) ((HttpURLConnection) connection).disconnect();
    }

    return false;
  }