跟踪文件导入数据库

我需要使用以下 Java 代码测试文件导入状态：

    @EventListener
    public void handleContextStart(ContextRefreshedEvent eventd) throws IOException, InterruptedException {
        System.out.println("Handling context started event.!!!");

        System.out.println("Running file verifier");
        System.out.println("monitoring folder " + folderPath);

        WatchService watchService = FileSystems.getDefault().newWatchService();
        Path path = Paths.get(folderPath);
        path.register(watchService, StandardWatchEventKinds.ENTRY_CREATE, StandardWatchEventKinds.ENTRY_DELETE, StandardWatchEventKinds.ENTRY_MODIFY);
        WatchKey key;
        while ((key = watchService.take()) != null) {
            for (WatchEvent<?> event : key.pollEvents()) {
                System.out.println("Event kind:" + event.kind() + ". File affected: " + event.context() + ".");
                if(event.kind().equals(StandardWatchEventKinds.ENTRY_DELETE)){
                    Instant start = Instant.now();

                    AtomicBoolean flag = new AtomicBoolean(true);

                    while(flag.get()) {
                        while ((key = watchService.take()) != null) {

                            List<EntityImportRequestsTable> list = entityImportRequestsService.findAll();
                            HashMap<String, String> map = new HashMap<>();
                            for(EntityImportRequestsTable item : list){
                                map.put(item.getRequestXmlSourceFile(), item.getStatusCode());
                            }

                            map.entrySet().forEach(entry -> {
                                System.out.println(entry.getKey() + " " + entry.getValue());

                                // compare file name from list and file name from the delete event by file name
                                if(entry.getKey().contains(event.context().toString())){
                                    // exit the monitoring while loop
                                    flag.set(false);
                                }
                            });
                        }
                        Thread.sleep(1000);
                    }

                    Instant end = Instant.now();
                    System.out.println(Duration.between(start,end));

                    long seconds = TimeUnit.MILLISECONDS.toSeconds(Duration.between(start,end).getSeconds());
                    long minutes = TimeUnit.MILLISECONDS.toMinutes(Duration.between(start,end).getSeconds());

                    System.out.format("Execution time %d minutes %d seconds", minutes, seconds);


                }

            }
            key.reset();
        }

        watchService.close();
    }

当从测试的应用程序处理文件时，该文件将被删除并导入到数据库中。如果文件导入成功，则状态已完成。

当我运行上面的程序时，没有任何反应。您知道如何正确跟踪文件导入吗？

您对事件的循环是有缺陷的，因为它会跳过事件，因为您有两次调用watchService.take()。第二个调用可能会阻塞，如果它有效，事件将被跳过，因此内部循环可能永远不会正确匹配删除或退出。删除第二个take():

while ((key = watchService.take()) != null) {
   ... 
   while ((key = watchService.take()) != null) {
   ... 

这是设置 WatchService 的逻辑示例，您应该尝试使用System.out.println()了解它是如何工作的：

Path watchDir = Path.of("whatever");
try (WatchService service = watchDir.getFileSystem().newWatchService()) {

    // Add whatever StandardWatchEventKinds events you need
    WatchKey wk = watchDir.register(service, StandardWatchEventKinds.ENTRY_DELETE /*, ENTRY_CREATE ENTRY_DELETE ... ETC */);
    // Insert your own loop termination condition here:
    while (running) {
        WatchKey key = service.poll(1, TimeUnit.SECONDS);
        if (key == null) {
            continue;
        }

        for (var event : key.pollEvents())  {
            Path evPath  = (Path) event.context();
            Path absPath = ((Path) key.watchable()).resolve(evPath);
            Kind<?> kind = event.kind();

            System.out.println("Kind=" + kind + " Path=" + evPath+" AbsPath=" + absPath);
            // Check each event to see if your termination condition is met
        }

        key.reset();
    }
}

运行上面的命令应该会让您了解什么WatchService提供，您可以将自己的逻辑填写到pollEvents()循环处理每个删除通知：

 // Check each event to see if your termination condition is met
 if (kind == StandardWatchEventKinds.ENTRY_DELETE) {
     if (absPath is one of the files you want) {
         Mark as received + print timings
         running = (number of remaining files you want > 0);
     }
 }

您可能会发现将监视服务部分重构为单独的组件更容易，以便它整理事件并将一组更改传递给侦听器 - 请参阅例子在这里 https://stackoverflow.com/questions/65223686/java-watchservice-perform-action-on-event-using-threads/65251819#65251819.

如果循环内的侦听器/处理程序可能需要一些时间，请在单独的线程中运行监视服务和处理程序，以便事件循环跟上监视事件发布，并且不要使用sleep因为这可能会导致溢出事件，因为您的侦听器/处理程序太慢。