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Java > Open Source Codes > org > apache > mina > util > AvailablePortFinder


1 /*
2  * Licensed to the Apache Software Foundation (ASF) under one
3  * or more contributor license agreements. See the NOTICE file
4  * distributed with this work for additional information
5  * regarding copyright ownership. The ASF licenses this file
6  * to you under the Apache License, Version 2.0 (the
7  * "License"); you may not use this file except in compliance
8  * with the License. You may obtain a copy of the License at
9  *
10  * http://www.apache.org/licenses/LICENSE-2.0
11  *
12  * Unless required by applicable law or agreed to in writing,
13  * software distributed under the License is distributed on an
14  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15  * KIND, either express or implied. See the License for the
16  * specific language governing permissions and limitations
17  * under the License.
18  *
19  */
20 package org.apache.mina.util;
21
22 import java.io.IOException JavaDoc;
23 import java.net.DatagramSocket JavaDoc;
24 import java.net.ServerSocket JavaDoc;
25 import java.util.NoSuchElementException JavaDoc;
26 import java.util.Set JavaDoc;
27 import java.util.TreeSet JavaDoc;
28
29 /**
30  * Finds currently available server ports.
31  *
32  * @author The Apache Directory Project (mina-dev@directory.apache.org)
33  * @version $Rev: 555855 $
34  * @see <a HREF="http://www.iana.org/assignments/port-numbers">IANA.org</a>
35  */
36 public class AvailablePortFinder {
37     /**
38      * The minimum number of server port number.
39      */
40     public static final int MIN_PORT_NUMBER = 1;
41
42     /**
43      * The maximum number of server port number.
44      */
45     public static final int MAX_PORT_NUMBER = 49151;
46
47     /**
48      * Creates a new instance.
49      */
50     private AvailablePortFinder() {
51     }
52
53     /**
54      * Returns the {@link Set} of currently available port numbers
55      * ({@link Integer}). This method is identical to
56      * <code>getAvailablePorts(MIN_PORT_NUMBER, MAX_PORT_NUMBER)</code>.
57      *
58      * WARNING: this can take a very long time.
59      */
60     public static Set JavaDoc<Integer JavaDoc> getAvailablePorts() {
61         return getAvailablePorts(MIN_PORT_NUMBER, MAX_PORT_NUMBER);
62     }
63
64     /**
65      * Gets the next available port starting at the lowest port number.
66      *
67      * @throws NoSuchElementException if there are no ports available
68      */
69     public static int getNextAvailable() {
70         return getNextAvailable(MIN_PORT_NUMBER);
71     }
72
73     /**
74      * Gets the next available port starting at a port.
75      *
76      * @param fromPort the port to scan for availability
77      * @throws NoSuchElementException if there are no ports available
78      */
79     public static int getNextAvailable(int fromPort) {
80         if ((fromPort < MIN_PORT_NUMBER) || (fromPort > MAX_PORT_NUMBER)) {
81             throw new IllegalArgumentException JavaDoc("Invalid start port: "
82                     + fromPort);
83         }
84
85         for (int i = fromPort; i <= MAX_PORT_NUMBER; i++) {
86             if (available(i)) {
87                 return i;
88             }
89         }
90
91         throw new NoSuchElementException JavaDoc("Could not find an available port "
92                 + "above " + fromPort);
93     }
94
95     /**
96      * Checks to see if a specific port is available.
97      *
98      * @param port the port to check for availability
99      */
100     public static boolean available(int port) {
101         if ((port < MIN_PORT_NUMBER) || (port > MAX_PORT_NUMBER)) {
102             throw new IllegalArgumentException JavaDoc("Invalid start port: " + port);
103         }
104
105         ServerSocket JavaDoc ss = null;
106         DatagramSocket JavaDoc ds = null;
107         try {
108             ss = new ServerSocket JavaDoc(port);
109             ss.setReuseAddress(true);
110             ds = new DatagramSocket JavaDoc(port);
111             ds.setReuseAddress(true);
112             return true;
113         } catch (IOException JavaDoc e) {
114         } finally {
115             if (ds != null) {
116                 ds.close();
117             }
118
119             if (ss != null) {
120                 try {
121                     ss.close();
122                 } catch (IOException JavaDoc e) {
123                     /* should not be thrown */
124                 }
125             }
126         }
127
128         return false;
129     }
130
131     /**
132      * Returns the {@link Set} of currently avaliable port numbers ({@link Integer})
133      * between the specified port range.
134      *
135      * @throws IllegalArgumentException if port range is not between
136      * {@link #MIN_PORT_NUMBER} and {@link #MAX_PORT_NUMBER} or
137      * <code>fromPort</code> if greater than <code>toPort</code>.
138      */
139     public static Set JavaDoc<Integer JavaDoc> getAvailablePorts(int fromPort, int toPort) {
140         if ((fromPort < MIN_PORT_NUMBER) || (toPort > MAX_PORT_NUMBER)
141                 || (fromPort > toPort)) {
142             throw new IllegalArgumentException JavaDoc("Invalid port range: "
143                     + fromPort + " ~ " + toPort);
144         }
145
146         Set JavaDoc<Integer JavaDoc> result = new TreeSet JavaDoc<Integer JavaDoc>();
147
148         for (int i = fromPort; i <= toPort; i++) {
149             ServerSocket JavaDoc s = null;
150
151             try {
152                 s = new ServerSocket JavaDoc(i);
153                 result.add(new Integer JavaDoc(i));
154             } catch (IOException JavaDoc e) {
155             } finally {
156                 if (s != null) {
157                     try {
158                         s.close();
159                     } catch (IOException JavaDoc e) {
160                         /* should not be thrown */
161                     }
162                 }
163             }
164         }
165
166         return result;
167     }
168 }
169
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