Added FreePortScanner to support module.

Author: poutsma

support/src/test/java/org/springframework/ws/transport/support/FreePortScanner.java

@@ -0,0 +1,99 @@
+/*
+ * Copyright 2005-2011 the original author or authors.
+ *
+ * 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.
+ */
+
+package org.springframework.ws.transport.support;
+
+import java.io.IOException;
+import java.net.InetSocketAddress;
+import java.net.ServerSocket;
+import java.util.Random;
+
+import org.springframework.util.Assert;
+
+/**
+ * Utility class that finds free BSD ports for use in testing scenario's.
+ *
+ * @author Ben Hale
+ * @author Arjen Poutsma
+ */
+public abstract class FreePortScanner {
+
+    private static final int MIN_SAFE_PORT = 1024;
+
+    private static final int MAX_PORT = 65535;
+
+    private static final Random random = new Random();
+
+    /**
+     * Returns the number of a free port in the default range.
+     */
+    public static int getFreePort() {
+        return getFreePort(MIN_SAFE_PORT, MAX_PORT);
+    }
+
+    /**
+     * Returns the number of a free port in the given range.
+     */
+    public static int getFreePort(int minPort, int maxPort) {
+        Assert.isTrue(minPort > 0, "'minPort' must be larger than 0");
+        Assert.isTrue(maxPort > minPort, "'maxPort' must be larger than minPort");
+        int portRange = maxPort - minPort;
+        int candidatePort;
+        int searchCounter = 0;
+        do {
+            if (++searchCounter > portRange) {
+                throw new IllegalStateException(
+                        String.format("There were no ports available in the range %d to %d", minPort, maxPort));
+            }
+            candidatePort = getRandomPort(minPort, portRange);
+        }
+        while (!isPortAvailable(candidatePort));
+
+        return candidatePort;
+    }
+
+    private static int getRandomPort(int minPort, int portRange) {
+        return minPort + random.nextInt(portRange);
+    }
+
+    private static boolean isPortAvailable(int port) {
+        ServerSocket serverSocket;
+        try {
+            serverSocket = new ServerSocket();
+        }
+        catch (IOException ex) {
+            throw new IllegalStateException("Unable to create ServerSocket.", ex);
+        }
+
+        try {
+            InetSocketAddress sa = new InetSocketAddress(port);
+            serverSocket.bind(sa);
+            return true;
+        }
+        catch (IOException ex) {
+            return false;
+        }
+        finally {
+            try {
+                serverSocket.close();
+            }
+            catch (IOException ex) {
+                // ignore
+            }
+        }
+    }
+
+}