Classes in this File | Line Coverage | Branch Coverage | Complexity | ||||
FileChangedReloadingStrategy |
|
| 2.0;2 |
1 | /* | |
2 | * Licensed to the Apache Software Foundation (ASF) under one or more | |
3 | * contributor license agreements. See the NOTICE file distributed with | |
4 | * this work for additional information regarding copyright ownership. | |
5 | * The ASF licenses this file to You under the Apache License, Version 2.0 | |
6 | * (the "License"); you may not use this file except in compliance with | |
7 | * the License. You may obtain a copy of the License at | |
8 | * | |
9 | * http://www.apache.org/licenses/LICENSE-2.0 | |
10 | * | |
11 | * Unless required by applicable law or agreed to in writing, software | |
12 | * distributed under the License is distributed on an "AS IS" BASIS, | |
13 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
14 | * See the License for the specific language governing permissions and | |
15 | * limitations under the License. | |
16 | */ | |
17 | ||
18 | package org.apache.commons.configuration.reloading; | |
19 | ||
20 | import java.io.File; | |
21 | import java.net.MalformedURLException; | |
22 | import java.net.URL; | |
23 | ||
24 | import org.apache.commons.configuration.ConfigurationUtils; | |
25 | import org.apache.commons.configuration.FileConfiguration; | |
26 | ||
27 | /** | |
28 | * <p>A reloading strategy that will reload the configuration every time its | |
29 | * underlying file is changed.</p> | |
30 | * <p>This reloading strategy does not actively monitor a configuration file, | |
31 | * but is triggered by its associated configuration whenever properties are | |
32 | * accessed. It then checks the configuration file's last modification date | |
33 | * and causes a reload if this has changed.</p> | |
34 | * <p>To avoid permanent disc access on successive property lookups a refresh | |
35 | * delay can be specified. This has the effect that the configuration file's | |
36 | * last modification date is only checked once in this delay period. The default | |
37 | * value for this refresh delay is 5 seconds.</p> | |
38 | * <p>This strategy only works with FileConfiguration instances.</p> | |
39 | * | |
40 | * @author Emmanuel Bourg | |
41 | * @version $Revision: 606798 $, $Date: 2007-12-25 20:05:58 +0100 (Di, 25 Dez 2007) $ | |
42 | * @since 1.1 | |
43 | */ | |
44 | 37 | public class FileChangedReloadingStrategy implements ReloadingStrategy |
45 | { | |
46 | /** Constant for the jar URL protocol.*/ | |
47 | private static final String JAR_PROTOCOL = "jar"; | |
48 | ||
49 | /** Constant for the default refresh delay.*/ | |
50 | private static final int DEFAULT_REFRESH_DELAY = 5000; | |
51 | ||
52 | /** Stores a reference to the configuration to be monitored.*/ | |
53 | protected FileConfiguration configuration; | |
54 | ||
55 | /** The last time the configuration file was modified. */ | |
56 | protected long lastModified; | |
57 | ||
58 | /** The last time the file was checked for changes. */ | |
59 | protected long lastChecked; | |
60 | ||
61 | /** The minimum delay in milliseconds between checks. */ | |
62 | 37 | protected long refreshDelay = DEFAULT_REFRESH_DELAY; |
63 | ||
64 | /** A flag whether a reload is required.*/ | |
65 | private boolean reloading; | |
66 | ||
67 | public void setConfiguration(FileConfiguration configuration) | |
68 | { | |
69 | 39 | this.configuration = configuration; |
70 | 39 | } |
71 | ||
72 | public void init() | |
73 | { | |
74 | 42 | updateLastModified(); |
75 | 42 | } |
76 | ||
77 | public boolean reloadingRequired() | |
78 | { | |
79 | 988 | if (!reloading) |
80 | { | |
81 | 987 | long now = System.currentTimeMillis(); |
82 | ||
83 | 987 | if (now > lastChecked + refreshDelay) |
84 | { | |
85 | 15 | lastChecked = now; |
86 | 15 | if (hasChanged()) |
87 | { | |
88 | 3 | reloading = true; |
89 | } | |
90 | } | |
91 | } | |
92 | ||
93 | 988 | return reloading; |
94 | } | |
95 | ||
96 | public void reloadingPerformed() | |
97 | { | |
98 | 1936 | updateLastModified(); |
99 | 1936 | } |
100 | ||
101 | /** | |
102 | * Return the minimal time in milliseconds between two reloadings. | |
103 | * | |
104 | * @return the refresh delay (in milliseconds) | |
105 | */ | |
106 | public long getRefreshDelay() | |
107 | { | |
108 | 2 | return refreshDelay; |
109 | } | |
110 | ||
111 | /** | |
112 | * Set the minimal time between two reloadings. | |
113 | * | |
114 | * @param refreshDelay refresh delay in milliseconds | |
115 | */ | |
116 | public void setRefreshDelay(long refreshDelay) | |
117 | { | |
118 | 15 | this.refreshDelay = refreshDelay; |
119 | 15 | } |
120 | ||
121 | /** | |
122 | * Update the last modified time. | |
123 | */ | |
124 | protected void updateLastModified() | |
125 | { | |
126 | 1978 | File file = getFile(); |
127 | 1978 | if (file != null) |
128 | { | |
129 | 1976 | lastModified = file.lastModified(); |
130 | } | |
131 | 1978 | reloading = false; |
132 | 1978 | } |
133 | ||
134 | /** | |
135 | * Check if the configuration has changed since the last time it was loaded. | |
136 | * | |
137 | * @return a flag whether the configuration has changed | |
138 | */ | |
139 | protected boolean hasChanged() | |
140 | { | |
141 | 14 | File file = getFile(); |
142 | 14 | if (file == null || !file.exists()) |
143 | { | |
144 | 1 | return false; |
145 | } | |
146 | ||
147 | 13 | return file.lastModified() > lastModified; |
148 | } | |
149 | ||
150 | /** | |
151 | * Returns the file that is monitored by this strategy. Note that the return | |
152 | * value can be <b>null </b> under some circumstances. | |
153 | * | |
154 | * @return the monitored file | |
155 | */ | |
156 | protected File getFile() | |
157 | { | |
158 | 1995 | return (configuration.getURL() != null) ? fileFromURL(configuration |
159 | .getURL()) : configuration.getFile(); | |
160 | } | |
161 | ||
162 | /** | |
163 | * Helper method for transforming a URL into a file object. This method | |
164 | * handles file: and jar: URLs. | |
165 | * | |
166 | * @param url the URL to be converted | |
167 | * @return the resulting file or <b>null </b> | |
168 | */ | |
169 | private File fileFromURL(URL url) | |
170 | { | |
171 | 1991 | if (JAR_PROTOCOL.equals(url.getProtocol())) |
172 | { | |
173 | 2 | String path = url.getPath(); |
174 | try | |
175 | { | |
176 | 2 | return ConfigurationUtils.fileFromURL(new URL(path.substring(0, |
177 | path.indexOf('!')))); | |
178 | } | |
179 | 0 | catch (MalformedURLException mex) |
180 | { | |
181 | 0 | return null; |
182 | } | |
183 | } | |
184 | else | |
185 | { | |
186 | 1989 | return ConfigurationUtils.fileFromURL(url); |
187 | } | |
188 | } | |
189 | } |