查找专用应用程序文件夹的位置 [英] Find place for dedicated application folder

问题描述

如果这个标题的名字不好，我很抱歉，我想不出更好的表达方式，因此欢迎编辑.

I'm sorry if this title is badly named, I can't think of a better way to phrase it and so edits would be welcomed.

我见过的大多数需要硬盘驱动器文件存储的应用程序都会根据操作系统在合适的位置创建一个文件夹.在 Windows 上，这些文件夹位于 Users[current user]AppData[etc]，在 Mac 上，这些文件夹位于/Users/[current user]/Library/Application Support/[etc]，Ubuntu 有一个类似的东西，我暂时想不起来.

Most applications I've seen that require hard drive file storage create a folder in a suitable place depending on the operating system. On Windows these folders lie in Users[current user]AppData[etc], on Mac these folders lie in /Users/[current user]/Library/Application Support/[etc], Ubuntu has a similar thing that I can't think of right now.

我想知道，这些文件路径是如何在不同用户的不同操作系统中始终找到的，至少在 java 中，是否有一种简单的方法来实现这一点?

I would like to know, how are these file paths consistently found in differing operating systems with different users, and is there, at least in java, a simple way to achieve this?

谢谢.

推荐答案

应该有，但没有.我什至提交了一个关于它的错误/RFE，但据我所知，它从未被接受.这是我使用的:

There should be, but there isn't. I even submitted a bug/RFE about it, but as far as I know, it was never accepted. Here's what I use:

public class ApplicationDirectories {
    private static final Logger logger =
        Logger.getLogger(ApplicationDirectories.class.getName());

    private static final Path config;

    private static final Path data;

    private static final Path cache;

    static {
        String os = System.getProperty("os.name");
        String home = System.getProperty("user.home");

        if (os.contains("Mac")) {
            config = Paths.get(home, "Library", "Application Support");
            data = config;
            cache = config;
        } else if (os.contains("Windows")) {
            String version = System.getProperty("os.version");
            if (version.startsWith("5.")) {
                config = getFromEnv("APPDATA", false,
                    Paths.get(home, "Application Data"));
                data = config;
                cache = Paths.get(home, "Local Settings", "Application Data");
            } else {
                config = getFromEnv("APPDATA", false,
                    Paths.get(home, "AppData", "Roaming"));
                data = config;
                cache = getFromEnv("LOCALAPPDATA", false,
                    Paths.get(home, "AppData", "Local"));
            }
        } else {
            config = getFromEnv("XDG_CONFIG_HOME", true,
                Paths.get(home, ".config"));
            data = getFromEnv("XDG_DATA_HOME", true,
                Paths.get(home, ".local", "share"));
            cache = getFromEnv("XDG_CACHE_HOME", true,
                Paths.get(home, ".cache"));
        }
    }

    /** Prevents instantiation. */
    private ApplicationDirectories() {
    }

    /**
     * Retrieves a path from an environment variable, substituting a default
     * if the value is absent or invalid.
     *
     * @param envVar name of environment variable to read
     * @param mustBeAbsolute whether enviroment variable's value should be
     *                       considered invalid if it's not an absolute path
     * @param defaultPath default to use if environment variable is absent
     *                    or invalid
     *
     * @return environment variable's value as a {@code Path},
     *         or {@code defaultPath}
     */
    private static Path getFromEnv(String envVar,
                                   boolean mustBeAbsolute,
                                   Path defaultPath) {
        Path dir;
        String envDir = System.getenv(envVar);
        if (envDir == null || envDir.isEmpty()) {
            dir = defaultPath;
            logger.log(Level.CONFIG,
                envVar + " not defined in environment"
                + ", falling back on "{0}"", dir);
        } else {
            dir = Paths.get(envDir);
            if (mustBeAbsolute && !dir.isAbsolute()) {
                dir = defaultPath;
                logger.log(Level.CONFIG,
                    envVar + " is not an absolute path"
                    + ", falling back on "{0}"", dir);
            }
        }
        return dir;
    }

    /**
     * Returns directory where the native system expects an application
     * to store configuration files for the current user.  No attempt is made
     * to create the directory, and no checks are done to see if it exists.
     *
     * @param appName name of application
     */
    public static Path configDir(String appName)
    {
        return config.resolve(appName);
    }

    /**
     * Returns directory where the native system expects an application
     * to store implicit data files for the current user.  No attempt is made
     * to create the directory, and no checks are done to see if it exists.
     *
     * @param appName name of application
     */
    public static Path dataDir(String appName)
    {
        return data.resolve(appName);
    }

    /**
     * Returns directory where the native system expects an application
     * to store cached data for the current user.  No attempt is made
     * to create the directory, and no checks are done to see if it exists.
     *
     * @param appName name of application
     */
    public static Path cacheDir(String appName)
    {
        return cache.resolve(appName);
    }
}

一些注意事项:

我不确定旧 Windows 版本的代码是否必要，因为 Java 8 不能在 Windows XP 上运行.

I'm not sure the code for older Windows versions is even necessary, as Java 8 doesn't run on Windows XP.

XDG 目录规范 说所有路径都在这些环境变量必须是绝对的.如果实现在这些变量中的任何一个中遇到相对路径，它应该认为该路径无效并忽略它."

The XDG Directory Specification says "All paths set in these environment variables must be absolute. If an implementation encounters a relative path in any of these variables it should consider the path invalid and ignore it."

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