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我想在文件停止修改時觸發一個事件。我輪詢一個目錄,如果文件名匹配到「input.csv」,那麼我想在該文件上觸發一個事件。檢查文件是否被修改的時間是10秒。當沒有事件發生時,我得到一個空指針異常。 這是我的示例代碼:如何在未使用Java WatchService修改文件時觸發事件?
public class MyPoller {
public static void main(String[] args) throws URISyntaxException,
IOException, InterruptedException {
Path tmpPath = Paths.get("E:/MyDirectory/DEC");
WatchService watchService = FileSystems.getDefault().newWatchService();
// Watching the E:/MyDirectory/DEC directory
// for MODIFY and DELETE operations
tmpPath.register(watcput.csvService, StandardWatchEventKinds.ENTRY_MODIFY,
StandardWatchEventKinds.ENTRY_DELETE);
for (;;) {
WatchKey key = watchService.poll(10000,TimeUnit.MILLISECONDS);
List<WatchEvent<?>> events = key.pollEvents();
// Poll all the events queued for the key
for (WatchEvent event : events) {
switch (event.context().toString()) {
case "input.csv":
System.out.println("Modified: " + event.context());
String filename = "" + event.context();
System.out.println(" "+filename);
break;
default:
break;
}
}
boolean valid = key.reset();
// If the key is invalid, just exit.
if (!valid) {
break;
}
}
}
}