创建临时文件中的Andr​​oid NDK用 [英] Creating temporary files in Android with NDK

问题描述

我目前工作的一个基于C语言的基于NDK-，Android应用程序。此应用程序需要创建临时文件。定期Linux系统上，我会使用 TMPFILE ，以确保这些文件在临时目录中正确地创建和清理后的在过程结束。

I am currently working on a C-based, NDK-based, Android application. This application needs to create temporary files. On a regular Linux system, I would use tmpfile to ensure that these files are properly created in a temporary directory and cleaned-up at process end.

不过，我在各种Android设备的研究似乎表明，

However, my investigations on various Android devices seem to indicate that

• TMPFILE 总是失败;


• 没有 / tmp目录目录;


• 目录 /数据/本地/ tmp目录不是在Android上的所有变体present;


• 没有 TEMP 环境变量设置;


• mkstemp 不工作比任何 TMPFILE 更好。

• tmpfile always fails;
• there is no /tmp directory;
• directory /data/local/tmp isn't present on all variants of Android;
• there is no TEMP environment variable set;
• mkstemp doesn't work any better than tmpfile.

现在，我敢肯定，我可以砍的东西在一起，但看到该SDK提供了 context.getCacheDir 和 File.createTempFile Java应用程序，我希望有一个在C级等同。

Now, I'm sure that I could hack something together, but seeing that the SDK offers context.getCacheDir and File.createTempFile for Java applications, I hope that there is an equivalent at C-level.

有谁知道一个良好的可靠的和交叉的Andr​​oid方法创建一个临时文件？

Does anyone know of a good reliable and cross-Android method for creating a temporary file?

推荐答案

我们已经找到了最好的方法是调用 Context.getCacheDir 启动时，用得到它的路径 getAbsolutePath ，然后调用一个JNI函数该路径存储在一个全球性的。想要创建一个临时文件中的任何功能，只是附加了一个合适的临时文件名的路径。

The best way we've found is to call Context.getCacheDir on startup, get its path with getAbsolutePath, then call a JNI function to store that path in a global. Any function that wants to create a temporary file simply appends a suitable temporary file name to that path.

如果你真的想从JNI去取另一种方法是在上下文来传递给JNI的功能和使用一堆的GetMethodID的 / CallObjectMethod 东西回调到Java来 getCacheDir ，但前者的做法是简单得多。

If you really want to fetch it from JNI another alternative would be to pass in a Context to a JNI function and use a bunch of GetMethodID / CallObjectMethod stuff to call back into Java to getCacheDir, but the former approach is a lot simpler.

不幸的是，似乎没有要在此刻更优雅的解决方案。

Unfortunately, there does not appear to be a more elegant solution at the moment.

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