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1   /*
2    * $Id: DirectoryFileStateMonitor.java,v 1.1 2004/04/27 10:59:15
3    * johndavidtaylor Exp $ Created on Apr 26, 2004 by jdt@roe.ac.uk The alipes
4    * project Copyright
5    *  
6    */
7   package org.abraracourcix.alipes.monitors.file;
8   import java.io.File;
9   import java.io.FileFilter;
10  import java.io.IOException;
11  import java.util.Set;
12  
13  import org.abraracourcix.alipes.listeners.Listener;
14  /***
15   * Like a FileStateMonitor, but monitors a specifig directory, rather than a
16   * specific collection of files. Why? We want to allow for new files being
17   * created. @TODO we're going to need to allow filters though.
18   * 
19   * @author jdt
20   */
21  public class DirectoryFileStateMonitor extends AbstractFileStateMonitor {
22      /***
23       * Directory we're monitoring.
24       */
25      private File dir;
26      /***
27       * Constructor
28       * 
29       * @param listener listener
30       * @param pollingFrequency frequency of polling (see PollingMonitor)
31       * @param dir directory to monitor
32       */
33      public DirectoryFileStateMonitor(
34          final Listener listener,
35          final long pollingFrequency,
36          final File dir) {
37          super(listener, pollingFrequency);
38          this.dir = dir;
39          updateFileList(true);
40      }
41      /***
42       * Constructor
43       * 
44       * @param listener listener
45       * @param pollingFrequency frequency of polling (see PollingMonitor)
46       * @param dir directory to monitor
47       * @param fileFilter filter to apply to the files in the directory
48       * @throws IOException if the directory does not exist
49       */
50      public DirectoryFileStateMonitor(
51          final Listener listener,
52          final int pollingFrequency,
53          final File dir,
54          final FileFilter fileFilter) {
55          this(listener, pollingFrequency, dir);
56          this.filter = fileFilter;
57      }
58      /***
59       * Commons-logging logger
60       */
61      private static org.apache.commons.logging.Log log =
62          org.apache.commons.logging.LogFactory.getLog(FileStateMonitor.class);
63      private FileFilter filter = null;
64      /***
65       * Check the directory to see if any new files have appeared
66       * This checks the root folder, and includes any folders within that folder, but it
67       * is not recursive, so it does not drill down into subfolders.  The root folder itself
68       * is also included in the list.  Note that overtime this list could bloat and bloat
69       * as there is no mechanism for removing files once they're in.
70       * 
71       * @param treatAsUnknown sets the initial state you want for the file - if
72       *            the program has started up, you probably want it to be set to
73       *            UNKNOWN, so set this argument to true, otherwise will be as
74       *            newly created
75       */
76      private void updateFileList(final boolean treatAsUnknown) {
77          assert dir != null;
78          
79          final Set existingFiles = getMonitoredFiles();
80          assert existingFiles != null;
81          final File[] files = dir.listFiles(filter);
82          if (files!=null ) {
83              // null indicates that this is perhaps not a directory
84              // so it contains no files
85  
86              for (int i = 0; i < files.length; ++i) {
87                  final File candidate = files[i];
88                  if (!(existingFiles.contains(candidate))) {
89                      addFile(
90                          candidate,
91                          treatAsUnknown
92                              ? FileState.UNKNOWN
93                              : FileState.FILE_NO_EXIST);
94                  }
95              }
96          }
97          //Add the directory itself
98          final File candidate = dir;
99          if (!(existingFiles.contains(candidate))) {
100             addFile(
101                     candidate,
102                     treatAsUnknown
103                     ? FileState.UNKNOWN
104                     : FileState.FILE_NO_EXIST);
105         }       
106     }
107     /***
108      * Check the file list and respond acccordingly @TODO deal with exception
109      * properly
110      * 
111      * @see org.abraracourcix.alipes.monitors.PollingMonitor#pole()
112      */
113     public final void pole() {
114         updateFileList(false);
115         //@TODO this doesn't need to be done every pole, but just for now....
116         checkTheFiles();
117     }
118 }
119 /*
120  * $Log: DirectoryFileStateMonitor.java,v $
121  * Revision 1.2  2004/06/03 15:50:24  johndavidtaylor
122  * Refactored DirChangeFileStateMonitor's behaviour when 
123  * the directory it monitors disappears.  Wired up the DirChangeEmailAlerter.
124  * Revision 1.1 2004/04/27 10:59:15
125  * johndavidtaylor Refactored and added a directory monitor
126  *  
127  */