Here you can find the source of serverListening(String host, int port)
public static boolean serverListening(String host, int port)
//package com.java2s; /*//from w w w . j a va2s . co m * Copyright (c) 2017 by Emanuel Seibold (BayDev). * * GNU AFFERO GENERAL PUBLIC LICENSE * Version 3, 19 November 2007 * * Copyright (C) 2007 Free Software Foundation, Inc. <http://fsf.org/> * Everyone is permitted to copy and distribute verbatim copies * of this license document, but changing it is not allowed. * * Preamble * * The GNU Affero General Public License is a free, copyleft license for * software and other kinds of works, specifically designed to ensure * cooperation with the community in the case of network server software. * * The licenses for most software and other practical works are designed * to take away your freedom to share and change the works. By contrast, * our General Public Licenses are intended to guarantee your freedom to * share and change all versions of a program--to make sure it remains free * software for all its users. * * When we speak of free software, we are referring to freedom, not * price. 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If not, see <http://www.gnu.org/licenses/>. * * Also add information on how to contact you by electronic and paper mail. * * If your software can interact with users remotely through a computer * network, you should also make sure that it provides a way for users to * get its source. For example, if your program is a web application, its * interface could display a "Source" link that leads users to an archive * of the code. There are many ways you could offer source, and different * solutions will be better for different programs; see section 13 for the * specific requirements. * * You should also get your employer (if you work as a programmer) or school, * if any, to sign a "copyright disclaimer" for the program, if necessary. * For more information on this, and how to apply and follow the GNU AGPL, see * <http://www.gnu.org/licenses/>. */ import java.net.Socket; public class Main { public static boolean serverListening(String host, int port) { Socket s = null; try { s = new Socket(host, port); return true; } catch (Exception e) { return false; } finally { if (s != null) { try { s.close(); } catch (Exception e) { } } } } }