Java目录监视器源程序

package com.lightspeedleader.directorywatcher; import java.io.File; import java.util.HashMap; import java.util.Iterator; import java.util.Map; public class DirectoryWatcher extends AbstractResourceWatcher { /** * The current map of files and their timestamps (String fileName => Long * lastMod) */ private Map currentFiles = new HashMap(); /** * The directory to watch. */ private String directory; /** * The map of last recorded files and their timestamps (String fileName => * Long lastMod) */ private Map prevFiles = new HashMap(); /** * Constructor that takes the directory to watch. * * @param directoryPath the directory to watch * @param intervalSeconds The interval to use when monitoring this * directory. I.e., ever x seconds, check this directory to see * what has changed. * @throws IllegalArgumentException if the argument does not map to a * valid directory */ public DirectoryWatcher(String directoryPath, int intervalSeconds) throws IllegalArgumentException { //Get the common thread interval stuff set up. super(intervalSeconds, directoryPath + " interval watcher."); //Check that it is indeed a directory. File theDirectory = new File(directoryPath); if (theDirectory != null && !theDirectory.isDirectory()) { //This is bad, so let the caller know String message = "The path " + directory + " does not represent a valid directory."; throw new IllegalArgumentException(message); } //Else all is well so set this directory and the interval this.directory = directoryPath; } /** * For testing only. * * @param args */ public static void main(String[] args) { // Monitor e:/cyc every 5 seconds DirectoryWatcher dw = new DirectoryWatcher("E:/cyc/", 5); dw.addListener(new FileListener()); dw.start(); } /** * Start the monitoring of this directory. */ public void start() { //Since we're going to start monitoring, we want to take a snapshot of the //current directory to we have something to refer to when stuff changes. takeSnapshot(); //And start the thread on the given interval super.start(); //And notify the listeners that monitoring has started File theDirectory = new File(directory); monitoringStarted(theDirectory); } /** * Stop the monitoring of this directory. */ public void stop() { //And start the thread on the given interval super.stop(); //And notify the listeners that monitoring has started File theDirectory = new File(directory); monitoringStopped(theDirectory); } /** * Store the file names and the last modified timestamps of all the files * and directories that exist in the directory at this moment. */ private void takeSnapshot() { //Set the last recorded snap shot to be the current list prevFiles.clear(); prevFiles.putAll(currentFiles); //And get a new current state with all the files and directories currentFiles.clear(); File theDirectory = new File(directory); File[] children = theDirectory.listFiles(); //Store all the current files and their timestamps for (int i = 0; i < children.length; i++) { File file = children[i]; currentFiles.put(file.getAbsolutePath(), new Long(file.lastModified())); } } /** * Check this directory for any changes and fire the proper events. */ protected void doInterval() { //Take a snapshot of the current state of the dir for comparisons takeSnapshot(); //Iterate through the map of current files and compare //them for differences etc... Iterator currentIt = currentFiles.keySet().iterator(); while (currentIt.hasNext()) { String fileName = (String) currentIt.next(); Long lastModified = (Long) currentFiles.get(fileName); //If this file did not exist before, but it does now, then //it's been added if (!prevFiles.containsKey(fileName)) { //DirectorySnapshot.addFile(fileName); resourceAdded(new File(fileName)); } //If this file did exist before else if (prevFiles.containsKey(fileName)) { Long prevModified = (Long) prevFiles.get(fileName); //If this file existed before and has been modified if (prevModified.compareTo(lastModified) != 0) { // 27 June 2006 // Need to check if the file are removed and added // during the interval /* if (!DirectorySnapshot.containsFile(fileName)) { resourceAdded(new File(fileName)); } else {*/ resourceChanged(new File(fileName)); //} } } } //Now we need to iterate through the list of previous files and //see if any that existed before don't exist anymore Iterator prevIt = prevFiles.keySet().iterator(); while (prevIt.hasNext()) { String fileName = (String) prevIt.next(); //If this file did exist before, but it does not now, then //it's been deleted if (!currentFiles.containsKey(fileName)) { //DirectorySnapshot.removeFile(fileName); resourceDeleted(fileName); } } } }