001package ca.uhn.fhir.util;
002
003/*
004 * #%L
005 * HAPI FHIR - Core Library
006 * %%
007 * Copyright (C) 2014 - 2016 University Health Network
008 * %%
009 * Licensed under the Apache License, Version 2.0 (the "License");
010 * you may not use this file except in compliance with the License.
011 * You may obtain a copy of the License at
012 * 
013 *      http://www.apache.org/licenses/LICENSE-2.0
014 * 
015 * Unless required by applicable law or agreed to in writing, software
016 * distributed under the License is distributed on an "AS IS" BASIS,
017 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
018 * See the License for the specific language governing permissions and
019 * limitations under the License.
020 * #L%
021 */
022
023
024import java.io.IOException;
025import java.net.ServerSocket;
026import java.util.ArrayList;
027import java.util.List;
028
029/**
030 * Provides server ports
031 */
032public class PortUtil {
033
034        private static List<Integer> ourPorts = new ArrayList<Integer>(); 
035        
036        /**
037         * This is really only used for unit tests but is included in the library so it can be reused across modules. Use with caution.
038         */
039        public static int findFreePort() {
040                ServerSocket server;
041                try {
042                        server = new ServerSocket(0);
043                        int port = server.getLocalPort();
044                        ourPorts.add(port);
045                        server.close();
046                        Thread.sleep(500);
047                        return port;
048                } catch (IOException e) {
049                        throw new Error(e);
050                } catch (InterruptedException e) {
051                        throw new Error(e);
052                }
053        }
054
055        public static List<Integer> list() {
056                return ourPorts;
057        }
058
059}
060