X-Git-Url: http://wamblee.org/gitweb/?a=blobdiff_plain;f=support%2Fgeneral%2Fsrc%2Fmain%2Fjava%2Forg%2Fwamblee%2Fio%2FDirectoryMonitor.java;fp=support%2Fgeneral%2Fsrc%2Fmain%2Fjava%2Forg%2Fwamblee%2Fio%2FDirectoryMonitor.java;h=0f84183c1b4478cdb32aad51dcc49b4145eeebc8;hb=32a62ca2c752e33a7873ac868a7a1f289caedcd4;hp=0000000000000000000000000000000000000000;hpb=d2bdf4e813c6a3964958c87b2ce56eaadf8a1f0a;p=utils

diff --git a/support/general/src/main/java/org/wamblee/io/DirectoryMonitor.java b/support/general/src/main/java/org/wamblee/io/DirectoryMonitor.java
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+++ b/support/general/src/main/java/org/wamblee/io/DirectoryMonitor.java
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+/*
+ * Copyright 2006 the original author or authors.
+ * 
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * 
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.wamblee.io;
+
+import java.io.File;
+import java.io.FileFilter;
+import java.util.ArrayList;
+import java.util.Date;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+
+/**
+ * Monitors a directory for changes.
+ * 
+ * @author Erik Brakkee
+ */
+public class DirectoryMonitor {
+
+	private static final Log LOG = LogFactory.getLog(DirectoryMonitor.class);
+
+	public static interface Listener {
+		
+		void fileChanged(File aFile);
+
+		void fileCreated(File aFile);
+
+		void fileDeleted(File aFile);
+	};
+
+	private File _directory;
+	private FileFilter _filter;
+	private Listener _listener;
+	private Map<File, Date> _contents;
+
+	public DirectoryMonitor(File aDirectory, FileFilter aFilefilter,
+			Listener aListener) {
+		_directory = aDirectory;
+		if (!_directory.isDirectory()) {
+			throw new IllegalArgumentException("Directory '" + _directory
+					+ "' does not exist");
+		}
+		_filter = aFilefilter;
+		_listener = aListener;
+		_contents = new HashMap<File, Date>();
+	}
+
+	/**
+	 * Polls the directory for changes and notifies the listener of any changes. 
+	 * In case of any exceptions thrown by the listener while handling the changes, 
+	 * the next call to this method will invoked the listeners again for the same changes. 
+	 */
+	public void poll() {
+		LOG.debug("Polling " + _directory);
+		Map<File, Date> newContents = new HashMap<File, Date>();
+		File[] files = _directory.listFiles(_filter);
+
+		// Check deleted files. 
+		Set<File> deletedFiles = new HashSet<File>(_contents.keySet());
+		for (File file : files) {
+			if (file.isFile()) {
+				if (_contents.containsKey(file)) {
+					deletedFiles.remove(file);
+				}
+			}
+		}
+		for (File file : deletedFiles) {
+			_listener.fileDeleted(file);
+		}
+		
+		for (File file : files) {
+			if (file.isFile()) {
+				if (_contents.containsKey(file)) {
+					Date oldDate = _contents.get(file);
+					if (file.lastModified() != oldDate.getTime()) {
+						_listener.fileChanged(file);
+					} else {
+						// No change.
+					}
+					newContents.put(file, new Date(file.lastModified()));
+				} else {
+					_listener.fileCreated(file);
+					newContents.put(file, new Date(file.lastModified()));
+				}
+			}
+		}
+		
+		_contents = newContents;
+	}
+
+}