Android检测url地址是否可达的两种方法

try{
  URL url = new URL(address);
  HttpURLConnection conn = (HttpURLConnection)url.openConnection();
  conn.setUseCaches(false);
  conn.setInstanceFollowRedirects(true);
  conn.setConnectTimeout(waitMilliSecond);
  conn.setReadTimeout(waitMilliSecond);

  //HTTP connect
  try {
    conn.connect();
  } catch(Exception e) {
    e.printStackTrace();
    return false;
  }

  int code = conn.getResponseCode();
  if ((code  = 100) && (code < 400)){
    return true;
  }

  return false;
}catch (Exception e){
  e.printStackTrace();
  return false;
}

try {
  URL url = new URL(address);
  String host = url.getHost();
  int port = url.getPort();
  if (port == -1) {
    port = 80;
  }
  Socket socket = new Socket();
  InetSocketAddress isa = new InetSocketAddress(InetAddress.getByName(host), port);

  socket.connect(isa, timeout);
  if (socket.isConnected()) {
    return true;
  } else {
    return false;
  }
} catch (Exception e) {
  e.printStackTrace();
} finally {
  if (socket != null) {
    try {
      socket.close();
    } catch (IOException e) {
      e.printStackTrace();
    }
  }
}