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Ian Darwin's assorted Java stuff,
assembled as an API.
package com.darwinsys.util;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.util.Vector;
/**
* A Reloading List - checks every n seconds if
* the file's timestamp has changed, and rereads if so.
* Based on Vector since all its methods are synchronized.
* X is a Y.
*/
public class ReloadingList extends Vector{
private static final long serialVersionUID = -2116296360428588971L;
/** the file we read from */
private File file;
/** numer of seconds to sleep before checking mtime */
private int seconds;
/** Default number of seconds for "seconds" */
private static final int DEFAULT_INTERVAL_SECONDS = 120;
/** time file last modified */
private long mtime;
public ReloadingList(String fileName) {
this(fileName, DEFAULT_INTERVAL_SECONDS);
}
public ReloadingList(String fileName, int seconds) {
this.file = new File(fileName);
if (!(file.exists() && file.isFile() && file.canRead()) ) {
throw new IllegalArgumentException("Not a readable file: " + fileName);
}
this.seconds = seconds;
final Thread watcher = new Thread(new Watcher());
// Don't keep main() running just for me!
watcher.setDaemon(true);
watcher.start();
}
protected synchronized void read() {
try {
BufferedReader is = new BufferedReader(new FileReader(file));
clear();
String line;
while ((line = is.readLine()) != null) {
add(line);
}
is.close();
mtime = file.lastModified();
} catch (IOException e) {
throw new RuntimeException(e.toString());
}
}
class Watcher implements Runnable {
public void run() {
while (true) {
if (mtime != file.lastModified()) {
read();
}
try {
Thread.sleep(1000 * seconds);
} catch (InterruptedException e) {
return;
}
}
}
}
}