ONOS-2580 Add rich type for transport layer port

Change-Id: I5cebed1671dd71274e4443618eb4d540aa43e65f

+package org.onlab.packet;
+
+/*
+ * Copyright 2014-2015 Open Networking Laboratory
+ *
+ * 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.
+ */
+
+/**
+ * Representation of a transport layer port.
+ */
+public class TransportPort {
+
+    private final int port;
+
+    // Transport layer port is unsigned 16 bits integer.
+    public static final int MAX_PORT = 0xFFFF;
+    public static final int MIN_PORT = 0;
+
+    /**
+     * Constructs a new TransportPort.
+     *
+     * @param value the transport layer port
+     */
+    protected TransportPort(int value) {
+        this.port = value;
+    }
+
+    /**
+     * Converts an integer into a TransportPort.
+     *
+     * @param value an integer representing the transport layer port
+     * @return a TransportPort
+     * @throws IllegalArgumentException if the value is invalid
+     */
+    public static TransportPort transportPort(int value) {
+        if (value < MIN_PORT || value > MAX_PORT) {
+            throw new IllegalArgumentException(
+                    "Transport layer port value " + value + "is not in the interval [0, 0xFFFF]");
+        }
+        return new TransportPort(value);
+    }
+
+    /**
+     * Returns the integer value for this transport port.
+     *
+     * @return an integer value
+     */
+    public int toInt() {
+        return this.port;
+    }
+
+    /*
+     * (non-Javadoc)
+     *
+     * @see java.lang.Object#equals(java.lang.Object)
+     */
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+
+        if (obj instanceof TransportPort) {
+
+            TransportPort other = (TransportPort) obj;
+
+            if (this.port == other.port) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    /*
+     * (non-Javadoc)
+     *
+     * @see java.lang.Object#hashCode()
+     */
+    @Override
+    public int hashCode() {
+        return this.port;
+    }
+
+    /*
+     * (non-Javadoc)
+     *
+     * @see java.lang.Object#toString()
+     */
+    @Override
+    public String toString() {
+        return String.valueOf(this.port);
+    }
+}