在O(1)中打开Scala / java中的文件打开文件描述符

当我没有关闭流时,我遇到了同样的问题(在Windows Server 2012 R2上).我重复遍历的所有文件都以读取模式打开,直到JVM关闭.但是,它并没有发生在Mac OS X上,并且由于流依赖于与FileSystemProvider和DirectoryStream的操作系统相关的实现,我认为该问题也可以依赖于操作系统.

相对于@Ian McLaird的评论,在Files.list()文档中提到

If timely disposal of file system resources is required,the try-with-resources construct should be used to ensure that the stream’s close method is invoked after the stream operations are completed.

返回的流是DirectoryStream,Javadoc说：

A DirectoryStream is opened upon creation and is closed by invoking the close method. Closing a directory stream releases any resources associated with the stream. Failure to close the stream may result in a resource leak.

我的解决方案是遵循建议并使用try-with-resources构造

try (Stream<Path> fileListing = Files.list(directoryPath)) {
    // use the fileListing stream
}

当我正确关闭流(使用上面的try-with-resources构造)时,文件句柄立即被释放.

如果您不关心将文件作为流传输,或者您可以将整个文件列表加载到内存中并将其自身转换为流,则可以使用IO API：

File directory = new File("/path/to/dir");
File[] files = directory.listFiles();
if (files != null) { // 'files' can be null if 'directory' "does not denote a directory,or if an I/O error occurs."
    // use the 'files' array or convert to a stream:
    Stream<File> fileStream = Arrays.stream(files);
}

我没有遇到任何文件锁定问题.但是请注意,这两种解决方案都依赖于本机的,依赖于操作系统的代码,因此我建议您在所有要使用的环境中进行测试.