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<!doctype html>
<html class="no-js" lang="en">
<head>
<meta charset="utf-8" />
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<title>
使用 Java 7 的 WatchService 监控目录 - TangJiujun's Techblog
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<h1>使用 Java 7 的 WatchService 监控目录</h1>
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<span class="date">2015/10/15</span>
<span>posted in </span>
<span class="posted-in"><a href='Java.html'>Java</a></span>
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<a href="http://blog.tangjiujun.com/java-file-watcher.html#disqus_thread">comments</a>
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<blockquote>
<p>在 Java 7 新增了 WatchService，它可以用来监控指定目录下的文件改动</p>
</blockquote>
<span id="more"></span><!-- more -->
<h3 id="toc_0">监控示例代码</h3>
<pre><code class="language-java">import java.io.IOException;
import java.nio.file.*;
public class DirectoryWatcher implements Runnable {
private final Path path; // 监控目录
private final WatchService watchService;
public DirectoryWatcher(Path path) {
this.path = path;
try {
this.watchService = FileSystems.getDefault().newWatchService();
} catch (IOException e) {
throw new RuntimeException("初始化 watchService 出错", e);
}
}
@Override
public void run() {
try {
path.register(watchService, StandardWatchEventKinds.ENTRY_CREATE);
} catch (IOException e) {
throw new RuntimeException("注册监控事件出错", e);
}
while (!Thread.interrupted()) {
if (!watch()) {
break;
}
}
try {
watchService.close();
} catch (IOException e) {
throw new RuntimeException("关闭 watchService 出错", e);
}
}
private boolean watch() {
WatchKey signal;
try {
// 等待监控信号
signal = watchService.take();
} catch (InterruptedException e) {
return false;
}
// 处理监控事件
for (WatchEvent<?> event : signal.pollEvents()) {
WatchEvent.Kind<?> kind = event.kind();
// 处理 OVERFLOW 事件
if (StandardWatchEventKinds.OVERFLOW.equals(kind)) {
continue;
}
System.out.println("事件：" + event.kind() + "，" + "文件名：" + event.context());
}
// 重置并继续监控
return signal.reset();
}
public static void main(String[] args) {
new Thread(new DirectoryWatcher(Paths.get("/for/bar"))).run();
}
}
</code></pre>
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