哪些操作系统支持在 Java 中查看本机(类似 inotify)文件 [英] Which Operating Systems support native (inotify-like) file watching in Java

问题描述

java.nio.file.WatchService 的 JavaDoc 状态；

The JavaDoc for java.nio.file.WatchService states;

实现...是旨在直接映射到 本地文件事件通知设施(如果可用)，或使用原始机制，例如轮询，当本地设施不可用时.

The implementation ... is intended to map directly on to the native file event notification facility where available, or to use a primitive mechanism, such as polling, when a native facility is not available.

我认为这意味着它会在可以的情况下尝试轻量级的原生机制(类似于 Linux 上的 inotify)，如果不能，则进行轮询.

I assume this means it will try a lightweight, native mechanism when it can (something like inotify on Linux) and poll if it can not.

正确吗?

哪些操作系统可能或不可能提供这样的功能?Linux 的发行版级别真的很有用，或者我可以假设如果 JVM 在 *unix 上运行，它将得到支持吗?

What operating systems are likely or unlikely to provide such a facility? Distro level for Linux would be really useful or can I assume that if the JVM runs on *unix, it will be supported?

推荐答案

这应该是一个评论，但它太大了，不能这样发布...

This should have probably been a comment, but it's too big to post it as such...

我正在查看 jdk-9 源(也可以在 jdk-8 存储库中轻松搜索)，但这里有一些与您的问题评论相关的内容:

I am looking at jdk-9 sources (could easily be searched in the jdk-8 repo as well), but here is some relevant to your question comments:

   /**
     * Linux implementation of WatchService based on inotify.
     *
     * In summary a background thread polls inotify plus a socket used for the wakeup
     * mechanism. Requests to add or remove a watch, or close the watch service,
     * cause the thread to wakeup and process the request. Events are processed
     * by the thread which causes it to signal/queue the corresponding watch keys.
     */

 class LinuxWatchService  extends AbstractWatchService

对于窗户:

/*
 * Win32 implementation of WatchService based on ReadDirectoryChangesW.
 */

class WindowsWatchService extends AbstractWatchService

等等......你可以在下面找到所有可用的实现:

And so on.. you can find all the available implementations under:

 jdk/src/java.base/{windows|unix|solaris|linux...}/classes/sun/nio/fs/

由于操作系统实际支持此功能，因此您似乎需要查看实际发行版.

As what OS actually supports this, it seems like that would require for you to look at the actual distro.

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