java - 如何在Java中连续检查文件是否存在？ [复制]

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Watching a Directory for Changes in Java

(6个答案)


5年前关闭。




我打算制作一个程序来继续检查目录中是否存在文件。如果不是，请等待一段时间(例如5分钟的 sleep 时间)，然后再次检查目录。该程序必须继续运行，并且不应结束。

我想到过制作一个多线程程序。但是，我不知道该如何实现。如果还有其他选择，请告诉我。

最佳答案

To implement this functionality, called file change notification, a program must be able to detect what is happening to the relevant directory on the file system. One way to do so is to poll the file system looking for changes, but this approach is inefficient. It does not scale to applications that have hundreds of open files or directories to monitor.

The java.nio.file package provides a file change notification API, called the Watch Service API. This API enables you to register a directory (or directories) with the watch service. When registering, you tell the service which types of events you are interested in: file creation, file deletion, or file modification. When the service detects an event of interest, it is forwarded to the registered process. The registered process has a thread (or a pool of threads) dedicated to watching for any events it has registered for. When an event comes in, it is handled as needed.

您可以通过创建监视服务并注册各种事件来做到这一点。可以在 Oracle tutorial doc上找到更多详细信息。
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Answer 1

To implement this functionality, called file change notification, a program must be able to detect what is happening to the relevant directory on the file system. One way to do so is to poll the file system looking for changes, but this approach is inefficient. It does not scale to applications that have hundreds of open files or directories to monitor.

The java.nio.file package provides a file change notification API, called the Watch Service API. This API enables you to register a directory (or directories) with the watch service. When registering, you tell the service which types of events you are interested in: file creation, file deletion, or file modification. When the service detects an event of interest, it is forwarded to the registered process. The registered process has a thread (or a pool of threads) dedicated to watching for any events it has registered for. When an event comes in, it is handled as needed.

您可以通过创建监视服务并注册各种事件来做到这一点。可以在 Oracle tutorial doc上找到更多详细信息。
关于SO here的类似问题