DELETE_ON_CLOSE在Linux上关闭之前删除文件 [英] DELETE_ON_CLOSE deletes files before close on Linux

问题描述

我使用Java 7 nio API获得以下代码：

I have this following code using Java 7 nio API:

import java.io.IOException;
import java.io.ObjectOutputStream;
import java.io.OutputStream;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.StandardOpenOption;

public class TestDeleteOnClose {

    public static void main(String[] args) throws IOException {
        Path tmp = Files.createTempFile("a", "b");
        OutputStream out = Files.newOutputStream(tmp, StandardOpenOption.DELETE_ON_CLOSE);

        ObjectOutputStream os = new ObjectOutputStream(out);

        os.write(0);

        os.flush();
        System.out.println(Files.exists(tmp));
        os.close();
        System.out.println(Files.exists(tmp));
    }
}

在Windows上，我看到了我的期望，即 true false 。在Linux上，我看到 false false 。这是预期的吗？难道我做错了什么？
文件被过早删除的事实是有问题的，因为我需要测试它的大小，例如在写入之后。

On Windows, I see what I expect, i.e true false. On Linux I see false false. Is it expected? Am I doing something wrong? The fact that the file is deleted too early is problematic since I need to test it for its size for instance after having written to it.

我使用jdk7u25在Linux和Windows上都可以在具有RedHat或ArchLinux的机器上重现。

I use jdk7u25 on both Linux and Windows and could reproduce on machines with RedHat or ArchLinux on it.

编辑：即使我在另一次调用os.write（）之前测试文件是否存在我被告知该文件不再存在。如果我使用 CREATE 选项打开文件，那么我将看到 true true 。

even if I test for file existence before another call to os.write() I am told the file does not exist anymore. If I open the file with the CREATE options, then I will see true true.

推荐答案

看起来Linux JVM会在您打开文件后立即删除该文件，这在Linux上可以实现。这也是我实现它的方式。您必须自己跟踪已经写入文件的数量，例如：插入一个计算字节数的 FilterOutputStream 。

It looks like the Linux JVM deletes the file as soon as you open it, which makes sense as you can do that on Linux. That's how I would implement it too. You'll have to keep track of how much has been written to the file yourself, e.g. by interposing a FilterOutputStream that counts bytes.

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