/**
 * net util
 * 网络工具类
 * @author jing
 */
public class NetUtil {

//    创建日志对象
    private static Logger logger = LoggerFactory.getLogger(NetUtil.class);



    /**
     * find avaliable port  发现 可用  端口
     * 如果传入的端口正在使用，那么发现的可用的端口就是在当前的基础上面加一或者减一
     * 之后再判断
     * @param defaultPort
     * @return
     */
    public static int findAvailablePort(int defaultPort) {
        int portTmp = defaultPort;
        while (portTmp < 65535) {
            if (!isPortUsed(portTmp)) {
                return portTmp;
            } else {
                portTmp++;
            }
        }
        portTmp = defaultPort--;
        while (portTmp > 0) {
            if (!isPortUsed(portTmp)) {
                return portTmp;
            } else {
                portTmp--;
            }
        }
        throw new RuntimeException("no available port.");
    }

    /**
     * check port used
     *  检查端口是否被使用
     * @param port
     * @return
     */
    public static boolean isPortUsed(int port) {
        boolean used = false;
        ServerSocket serverSocket = null;
        try {
            serverSocket = new ServerSocket(port);
            used = false;
        } catch (IOException e) {
            logger.info(">>>>>>>>>>> xxl-job, port[{}] is in use.", port);
            used = true;
        } finally {
            if (serverSocket != null) {
                try {
                    serverSocket.close();
                } catch (IOException e) {
                    logger.info("");
                }
            }
        }
        return used;
    }


//    public static void main(String[] args) {
//        System.out.println(findAvailablePort(8082));
//    }

}