Java HTTP Port Find findFreePort(int start, int limit)

Description

find Free Port

License

Apache License

Declaration

public static int findFreePort(int start, int limit) 

Method Source Code

//package com.java2s;
//License from project: Apache License 

import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;

public class Main {
    public static int findFreePort(int start, int limit) {
        if (start == 0) {
            //bail out if the default is "dont care"
            return 0;
        }//from ww  w .  j a v a  2  s . co m
        int found = 0;
        int port = start;
        int finish = start + limit;
        while (found == 0 && port < finish) {
            if (isPortAvailable(port)) {
                found = port;
            } else {
                port++;
            }
        }
        return found;
    }

    /**
     * See if a port is available for listening on by trying to listen
     * on it and seeing if that works or fails.
     *
     * @param port port to listen to
     * @return true if the port was available for listening on
     */
    public static boolean isPortAvailable(int port) {
        try {
            ServerSocket socket = new ServerSocket(port);
            socket.close();
            return true;
        } catch (IOException e) {
            return false;
        }
    }

    /**
     * See if a port is available for listening on by trying connect to it
     * and seeing if that works or fails
     *
     * @param host
     * @param port
     * @return
     */
    public static boolean isPortAvailable(String host, int port) {
        try {
            Socket socket = new Socket(host, port);
            socket.close();
            return false;
        } catch (IOException e) {
            return true;
        }
    }
}

Related

1. findFreePort()
2. findFreePort()
3. findFreePort()
4. findFreePort()
5. findFreePort(int start, int len)
6. findFreePort(int startPort)
7. findFreePort(int startPort)
8. findFreePortExcepting(int portToExclude)
9. findFreePortForApi()