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/*******************************************************************************
* ============LICENSE_START========================================================================
* ONAP : ccsdk feature sdnr wt
* =================================================================================================
* Copyright (C) 2019 highstreet technologies GmbH Intellectual Property. All rights reserved.
* =================================================================================================
* 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.
* ============LICENSE_END==========================================================================
******************************************************************************/
import java.io.File;
import java.io.IOException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class TestFileChangeNotification {
/**
* Check every now and then that a certain file has not changed. If it has, then
* call the {@link #doOnChange} method.
*
* @author JunHo Yoon
* @since 3.1.1
*/
public static abstract class FileWatchdog extends Thread {
private static final Logger LOGGER = LoggerFactory.getLogger(FileWatchdog.class);
/**
* The default delay between every file modification check, set to 60
* seconds.
*/
public static final long DEFAULT_DELAY = 60000;
/**
* The name of the file to observe for changes.
*/
private String filename;
/**
* The delay to observe between every check. By default set
* {@link #DEFAULT_DELAY}.
*/
private long delay = DEFAULT_DELAY;
private File file;
private long lastModified = 0;
private boolean warnedAlready = false;
private boolean interrupted = false;
protected FileWatchdog(String filename) {
this.filename = filename;
file = new File(filename);
setDaemon(true);
checkAndConfigure();
}
/**
* Set the delay to observe between each check of the file changes.
*
* @param delay
* the frequency of file watch.
*/
public void setDelay(long delay) {
this.delay = delay;
}
/**
* abstract method to be run when the file is changed.
*/
protected abstract void doOnChange();
protected void checkAndConfigure() {
boolean fileExists;
try {
fileExists = file.exists();
} catch (SecurityException e) {
LOGGER.warn("Was not allowed to read check file existence, file:[" + filename + "].");
interrupted = true; // there is no point in continuing
return;
}
if (fileExists) {
long l = file.lastModified(); // this can also throw a
if (lastModified ==0) {
lastModified = l; // is very unlikely.
}
if (l > lastModified) { // however, if we reached this point this
lastModified = l; // is very unlikely.
doOnChange();
warnedAlready = false;
}
} else {
if (!warnedAlready) {
LOGGER.debug("[" + filename + "] does not exist.");
warnedAlready = true;
}
}
}
@Override
public void run() {
while (!interrupted && !isInterrupted()) {
try {
Thread.sleep(delay);
} catch (InterruptedException e) {
}
checkAndConfigure();
}
}
}
public static class SomeWatchFile extends FileWatchdog{
protected SomeWatchFile(String filename) {
super(filename);
this.setDelay(1000);
}
@Override
protected void doOnChange() {
System.out.println("File has changed");
}
}
public static void main(String args[]) throws IOException {
SomeWatchFile someWatchFile = new SomeWatchFile ("watchedFile.txt");
someWatchFile.start();
String fileName = "watchedFile.txt";
File tempFile = new File(fileName);
tempFile.createNewFile();
System.out.println("1. Press F5 in eclipse to see and modify 2. Press enter to exit");
System.in.read();
System.out.println("Remove file "+fileName);
tempFile.delete();
}
}
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