file.lastModified（）是从来没有什么被设置file.setLastModified（） [英] file.lastModified() is never what was set with file.setLastModified()

问题描述

我有一个问题，米利斯设置和读取在Android 2.3.4上的Nexus One。这是code：

I do have a problem with millis set and read on Android 2.3.4 on a Nexus One. This is the code:

File fileFolder = new File(Environment.getExternalStorageDirectory(), appName + "/" + URLDecoder.decode(folder.getUrl()));
if (fileFolder != null && !fileFolder.exists()) {
  fileFolder.setLastModified(1310198774);
  fileFolder.mkdirs();
  fileFolder.setLastModified(1310198774);
}

if (fileFolder != null && fileFolder.exists()) {
  long l = fileFolder.lastModified();
}

在这个小测试我写1310198774但是从上次更改时间（）返回的结果是1310199771000。

In this small test I write 1310198774 but the result that is returned from lastModified() is 1310199771000.

即使我砍尾000有几分钟的差别。

Even if I cut the trailing "000" there's a difference of several minutes.

我需要一个互联网服务和Android设备之间同步文件。的lastmodification米利斯是由该服务所发送的数据的一部分。我设置米利斯到创建/复制的文件和文件夹，以检查文件/文件夹需要被改写。

I need to sync files between a webservice and the Android device. The lastmodification millis are part of the data sent by this service. I do set the millis to the created/copied files and folders to check if the file/folder needs to be overwritten.

一切工作，但被从文件系统返回的米利斯从已设置的值不同。

Everything is working BUT the millis that are returned from the filesystem are different from the values that were set.

我是pretty的肯定有什么毛病我的code - 但我不能找到它。

I'm pretty sure there's something wrong with my code - but I can't find it.

在预先感谢。 HJW

Many thanks in advance. HJW

推荐答案

所以，也许我失去了一些东西，但我看到了一些问题，您的code以上。您的具体问题可能是由于（如@JB提到的）到Android问题，但留给后人，我想我会提供一个答案。

So maybe I'm missing something but I see some problems with your code above. Your specific problem may be due (as @JB mentioned) to Android issues but for posterity, I thought I'd provide an answer.

首先， File.setLastModified（）需要以毫秒为单位的时间。这里是的javadoc 。你似乎试图将其设置为秒。所以，你的code应该是这样的：

First off, File.setLastModified() takes the time in milliseconds. Here are the javadocs. You seem to be trying to set it in seconds. So your code should be something like:

fileFolder.setLastModified(1310198774000L);

正如的javadoc，许多文件系统仅支持秒粒度的最后修改时间。所以，如果你需要看到相同的修改时间的文件，那么你应该做类似如下：

As mentioned in the javadocs, many filesystems only support seconds granularity for last-modification time. So if you need to see the same modification time in a file then you should do something like the following:

private void changeModificationFile(File file, long time) {
    // round the value down to the nearest second
    file.setLastModified((time / 1000) * 1000);
}

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