View Javadoc

1   /*
2    * Copyright 2009 Red Hat, Inc.
3    *
4    * Red Hat licenses this file to you under the Apache License, version 2.0
5    * (the "License"); you may not use this file except in compliance with the
6    * License.  You may obtain a copy of the License at:
7    *
8    *    http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
13   * License for the specific language governing permissions and limitations
14   * under the License.
15   */
16  package org.jboss.netty.util.internal;
17  
18  import java.util.regex.Pattern;
19  
20  /**
21   * Accesses the system property swallowing a {@link SecurityException}.
22   *
23   * @author <a href="http://www.jboss.org/netty/">The Netty Project</a>
24   * @author <a href="http://gleamynode.net/">Trustin Lee</a>
25   *
26   * @version $Rev: 2161 $, $Date: 2010-02-18 11:12:15 +0900 (Thu, 18 Feb 2010) $
27   *
28   */
29  public class SystemPropertyUtil {
30  
31      /**
32       * Returns the value of the Java system property with the specified
33       * {@code key}.
34       *
35       * @return the property value.
36       *         {@code null} if there's no such property or if an access to the
37       *         specified property is not allowed.
38       */
39      public static String get(String key) {
40          try {
41              return System.getProperty(key);
42          } catch (Exception e) {
43              return null;
44          }
45      }
46  
47      /**
48       * Returns the value of the Java system property with the specified
49       * {@code key}, while falling back to the specified default value if
50       * the property access fails.
51       *
52       * @return the property value.
53       *         {@code def} if there's no such property or if an access to the
54       *         specified property is not allowed.
55       */
56      public static String get(String key, String def) {
57          String value = get(key);
58          if (value == null) {
59              value = def;
60          }
61          return value;
62      }
63  
64      /**
65       * Returns the value of the Java system property with the specified
66       * {@code key}, while falling back to the specified default value if
67       * the property access fails.
68       *
69       * @return the property value.
70       *         {@code def} if there's no such property or if an access to the
71       *         specified property is not allowed.
72       */
73      public static int get(String key, int def) {
74          String value = get(key);
75          if (value == null) {
76              return def;
77          }
78  
79          if (Pattern.matches("-?[0-9]+", value)) {
80              return Integer.parseInt(value);
81          } else {
82              return def;
83          }
84      }
85  
86      private SystemPropertyUtil() {
87          // Unused
88      }
89  }