Java7 文件变动监听
Java About 1,794 words使用场景
应用配置热更新。
代码
可用于监听单个文件变更。
public static void main(String[] args) {
try {
String filePath = System.getProperty("user.home");
WatchService watchService = FileSystems.getDefault().newWatchService();
Path path = Paths.get(filePath);
path.register(watchService, StandardWatchEventKinds.ENTRY_CREATE, StandardWatchEventKinds.ENTRY_DELETE, StandardWatchEventKinds.ENTRY_MODIFY, StandardWatchEventKinds.OVERFLOW);
System.out.println("开始监听文件夹#" + filePath);
WatchKey key;
while ((key = watchService.take()) != null) {
List<WatchEvent<?>> watchEvents = key.pollEvents();
for (WatchEvent<?> watchEvent : watchEvents) {
WatchEvent.Kind<?> kind = watchEvent.kind();
if (kind == StandardWatchEventKinds.ENTRY_CREATE) {
System.out.println("新建#" + watchEvent.context() + ", 次数#" + watchEvent.count());
} else if (kind == StandardWatchEventKinds.ENTRY_DELETE) {
System.out.println("删除#" + watchEvent.context() + ", 次数#" + watchEvent.count());
} else if (kind == StandardWatchEventKinds.ENTRY_MODIFY) {
System.out.println("修改#" + watchEvent.context() + ", 次数#" + watchEvent.count());
} else if (kind == StandardWatchEventKinds.OVERFLOW) {
System.out.println("overflow#" + watchEvent.context() + ", 次数#" + watchEvent.count());
}
}
key.reset();
}
} catch (Exception e) {
e.printStackTrace();
System.out.println("获取监听器失败");
}
}
注意
WatchService
监听的是文件夹,而不是文件。- 修改事件会连续触发两次,需去重。
- 只监听一级目录,二级目录事件不监听。
参考
https://docs.oracle.com/javase/tutorial/essential/io/notification.html
Views: 2,161 · Posted: 2020-09-27
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