Java HTTP Port Find getPorts(int count)

Description

Returns an array containing the specified number of available local ports.

License

Apache License

Parameter

Parameter	Description
count	Number of local ports to identify and return.

Exception

Parameter	Description
RuntimeException	if an I/O error occurs opening or closing a socket.

Return

an array of available local port numbers.

Declaration

public static int[] getPorts(int count) 

Method Source Code

//package com.java2s;
/**//from w  ww  . j  a v  a 2  s  .  co  m
 * Copyright 2015 Cerner Corporation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import java.io.IOException;
import java.net.ServerSocket;
import java.util.HashSet;

import java.util.Set;

public class Main {
    private static final Set<Integer> USED_PORTS = new HashSet<Integer>();

    /**
     * Returns an array containing the specified number of available local ports.
     *
     * @param count Number of local ports to identify and return.
     *
     * @return an array of available local port numbers.
     *
     * @throws RuntimeException if an I/O error occurs opening or closing a socket.
     */
    public static int[] getPorts(int count) {
        int[] ports = new int[count];
        Set<ServerSocket> openSockets = new HashSet<ServerSocket>(count + USED_PORTS.size());

        for (int i = 0; i < count;) {
            try {
                ServerSocket socket = new ServerSocket(0);
                int port = socket.getLocalPort();
                openSockets.add(socket);

                // Disallow port reuse.
                if (!USED_PORTS.contains(port)) {
                    ports[i++] = port;
                    USED_PORTS.add(port);
                }
            } catch (IOException e) {
                throw new RuntimeException("could not open socket", e);
            }
        }

        // Close the sockets so that their port numbers can be used by the caller.
        for (ServerSocket socket : openSockets) {
            try {
                socket.close();
            } catch (IOException e) {
                throw new RuntimeException("could not close socket", e);
            }
        }

        return ports;
    }
}

Related

1. getPort(int port)
2. getPort(Proxy proxy)
3. getPort(String endpoint)
4. getPort(String hostAndPort)
5. getPortInRange(int minPort, int maxPort)
6. getPorts(int number, int MIN_PORT_NUMBER, int MAX_PORT_NUMBER)
7. getPrometheusMetrics(int metricsPort)
8. getRandomAvailablePort()
9. getRandomFreePort()