Android Environment 获取的路径问题

1. 以获取 /System 路径为例

    /**
     * Return root of the "system" partition holding the core Android OS.
     * Always present and mounted read-only.
     */
    public static @NonNull File getRootDirectory() {
        return DIR_ANDROID_ROOT;
    }

    // ENV_ANDROID_ROOT 的值为 "ANDROID_ROOT"
    // private static final String ENV_ANDROID_ROOT = "ANDROID_ROOT";
   private static final File DIR_ANDROID_ROOT = getDirectory(ENV_ANDROID_ROOT, "/system");

    static File getDirectory(String variableName, String defaultPath) {
        // 获取环境变量 ANDROID_ROOT 对应的值
        String path = System.getenv(variableName);
        return path == null ? new File(defaultPath) : new File(path);
    }

1.1 获取环境变量 ANDROID_ROOT 对应的值

环境变量可以简单理解为可以在进程中获取的键值对。

2. 其他路径也是类似

    private static final File DIR_ANDROID_ROOT = getDirectory(ENV_ANDROID_ROOT, "/system");
    private static final String DIR_ANDROID_DATA_PATH = getDirectoryPath(ENV_ANDROID_DATA, "/data");
    private static final File DIR_ANDROID_DATA = new File(DIR_ANDROID_DATA_PATH);
    private static final File DIR_ANDROID_EXPAND = getDirectory(ENV_ANDROID_EXPAND, "/mnt/expand");
    private static final File DIR_ANDROID_STORAGE = getDirectory(ENV_ANDROID_STORAGE, "/storage");
    private static final File DIR_DOWNLOAD_CACHE = getDirectory(ENV_DOWNLOAD_CACHE, "/cache");
    private static final File DIR_METADATA = new File("/metadata");
    private static final File DIR_OEM_ROOT = getDirectory(ENV_OEM_ROOT, "/oem");
    private static final File DIR_ODM_ROOT = getDirectory(ENV_ODM_ROOT, "/odm");
    private static final File DIR_VENDOR_ROOT = getDirectory(ENV_VENDOR_ROOT, "/vendor");
    private static final File DIR_PRODUCT_ROOT = getDirectory(ENV_PRODUCT_ROOT, "/product");
    private static final File DIR_SYSTEM_EXT_ROOT = getDirectory(ENV_SYSTEM_EXT_ROOT,
            "/system_ext");
    private static final File DIR_APEX_ROOT = getDirectory(ENV_APEX_ROOT,
            "/apex");