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1
25
26 package net.sourceforge.cobertura.util;
27
28 import java.io.File  ;
29 import java.io.FileNotFoundException ;
30 import java.io.RandomAccessFile ;
31 import java.lang.reflect.InvocationTargetException ;
32 import java.lang.reflect.Method ;
33
34
49 public class FileLocker
50 {
51
52
55 private Object lock = null;
56
57
60 private Object lockChannel = null;
61
62
66 private File lockFile;
67
68 public FileLocker(File file)
69 {
70 String lockFileName = file.getName() + ".lock";
71 File parent = file.getParentFile();
72 if (parent == null)
73 {
74 lockFile = new File (lockFileName);
75 }
76 else
77 {
78 lockFile = new File (parent, lockFileName);
79 }
80 lockFile.deleteOnExit();
81 }
82
83
86 public boolean lock()
87 {
88 if (System.getProperty("java.version").startsWith("1.3"))
89 {
90 return true;
91 }
92
93 try
94 {
95 Class aClass = Class.forName("java.io.RandomAccessFile");
96 Method method = aClass.getDeclaredMethod("getChannel", (Class [])null);
97 lockChannel = method.invoke(new RandomAccessFile (lockFile, "rw"), (Object [])null);
98 }
99 catch (FileNotFoundException e)
100 {
101 System.err.println("Unable to get lock channel for " + lockFile.getAbsolutePath()
102 + ": " + e.getLocalizedMessage());
103 return false;
104 }
105 catch (InvocationTargetException e)
106 {
107 System.err.println("Unable to get lock channel for " + lockFile.getAbsolutePath()
108 + ": " + e.getLocalizedMessage());
109 return false;
110 }
111 catch (Throwable t)
112 {
113 System.err.println("Unable to execute RandomAccessFile.getChannel() using reflection: "
114 + t.getLocalizedMessage());
115 t.printStackTrace();
116 }
117
118 try
119 {
120 Class aClass = Class.forName("java.nio.channels.FileChannel");
121 Method method = aClass.getDeclaredMethod("lock", (Class [])null);
122 lock = method.invoke(lockChannel, (Object [])null);
123 }
124 catch (InvocationTargetException e)
125 {
126 System.err.println("Unable to get lock on " + lockFile.getAbsolutePath() + ": "
127 + e.getLocalizedMessage());
128 return false;
129 }
130 catch (Throwable t)
131 {
132 System.err.println("Unable to execute FileChannel.lock() using reflection: "
133 + t.getLocalizedMessage());
134 t.printStackTrace();
135 }
136
137 return true;
138 }
139
140
143 public void release()
144 {
145 if (lock != null)
146 lock = releaseFileLock(lock);
147 if (lockChannel != null)
148 lockChannel = closeChannel(lockChannel);
149 lockFile.delete();
150 }
151
152 private static Object releaseFileLock(Object lock)
153 {
154 try
155 {
156 Class aClass = Class.forName("java.nio.channels.FileLock");
157 Method method = aClass.getDeclaredMethod("isValid", (Class [])null);
158 if (((Boolean )method.invoke(lock, (Object [])null)).booleanValue())
159 {
160 method = aClass.getDeclaredMethod("release", (Class [])null);
161 method.invoke(lock, (Object [])null);
162 lock = null;
163 }
164 }
165 catch (Throwable t)
166 {
167 System.err.println("Unable to release locked file: " + t.getLocalizedMessage());
168 }
169 return lock;
170 }
171
172 private static Object closeChannel(Object channel)
173 {
174 try
175 {
176 Class aClass = Class.forName("java.nio.channels.spi.AbstractInterruptibleChannel");
177 Method method = aClass.getDeclaredMethod("isOpen", (Class [])null);
178 if (((Boolean )method.invoke(channel, (Object [])null)).booleanValue())
179 {
180 method = aClass.getDeclaredMethod("close", (Class [])null);
181 method.invoke(channel, (Object [])null);
182 channel = null;
183 }
184 }
185 catch (Throwable t)
186 {
187 System.err.println("Unable to close file channel: " + t.getLocalizedMessage());
188 }
189 return channel;
190 }
191
192 }
193 |
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