Created
March 18, 2014 15:24
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New Java 7 NIO.2 Watch API example.
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package com.edorasware.java7.nio2; | |
import com.sun.nio.file.SensitivityWatchEventModifier; | |
import java.io.IOException; | |
import java.nio.file.*; | |
import java.util.HashMap; | |
import java.util.Map; | |
public class WatchApp { | |
public static final Map<WatchEvent.Kind<Path>, String> EVENT_KINDS_AND_MESSAGES = new HashMap<>(); | |
public static final WatchEvent.Kind[] EVENT_KINDS; | |
static { | |
EVENT_KINDS_AND_MESSAGES.put(StandardWatchEventKinds.ENTRY_CREATE, "Created: '%s'.\n"); | |
EVENT_KINDS_AND_MESSAGES.put(StandardWatchEventKinds.ENTRY_DELETE, "Deleted: '%s'.\n"); | |
EVENT_KINDS_AND_MESSAGES.put(StandardWatchEventKinds.ENTRY_MODIFY, "Modified: '%s'.\n"); | |
EVENT_KINDS = getKeysAsArray(EVENT_KINDS_AND_MESSAGES); | |
} | |
private static WatchEvent.Kind[] getKeysAsArray(Map<WatchEvent.Kind<Path>, String> map) { | |
// WTF?? | |
return map.keySet().toArray(new WatchEvent.Kind[EVENT_KINDS_AND_MESSAGES.keySet().size()]); | |
} | |
public static void main(String[] args) throws IOException { | |
if (args.length < 1) { | |
throw new IllegalArgumentException("Error: directory to watch expected as CLI argument."); | |
} | |
Path watchedDirectory = Paths.get(args[0]); | |
new WatchApp().watch(watchedDirectory); | |
} | |
private void watch(Watchable watchable) throws IOException { | |
try (WatchService watchService = FileSystems.getDefault().newWatchService()) { | |
//watchable.register(watchService, EVENT_KINDS); // Standard behavior | |
watchable.register(watchService, EVENT_KINDS, SensitivityWatchEventModifier.HIGH); // Extended behavior with non-portable Event Modifier to reduce the delay | |
System.out.format("Watching: '%s' for changes.\n", watchable); | |
//while (processWatchKey(watchService.poll(500, TimeUnit.MILLISECONDS), EVENT_KINDS_AND_MESSAGES)) { // Polling call | |
while (processWatchKey(watchService.take(), EVENT_KINDS_AND_MESSAGES)) { // Blocking call | |
System.out.print("."); | |
} | |
} catch (InterruptedException e) { | |
System.out.println("Watcher service interrupted."); | |
} | |
} | |
private boolean processWatchKey(WatchKey watchKey, Map<WatchEvent.Kind<Path>, String> messages) { | |
if (watchKey == null) { | |
return true; | |
} | |
for (WatchEvent event : watchKey.pollEvents()) { | |
Object context = event.context(); | |
String message = messages.get(event.kind()); | |
if (message != null) { | |
System.out.format(message, context.toString()); | |
String jsFileStringPath = getJSFileStringPath(context); | |
if (jsFileStringPath != null) { | |
System.out.format("JS file: '%s'.\n", jsFileStringPath); | |
} | |
} else { | |
System.out.format("No message for event of kind: '%s'.\n", event.kind()); | |
} | |
} | |
return watchKey.reset(); | |
} | |
private static String getJSFileStringPath(Object context) { | |
if (Path.class.isInstance(context)) { | |
Path path = Path.class.cast(context); | |
String fileName = path.getFileName().toString(); | |
//if (path.toFile().isFile() && fileName.endsWith(".js")) { // This should return true in the case of a regular file with .js extension?? | |
if (fileName.endsWith(".js")) { | |
return fileName; | |
} | |
} | |
return null; | |
} | |
} |
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