如何在Android中获取SD卡(辅助)存储路径？

Question

我正在开发一个文件管理器应用程序.我希望向用户显示内部存储和SD卡存储(如果存在).对于我使用的内部存储Environment.getExternalStorageDirectory().getPath().我怎样才能获得SD存储？

Answer 1

不确定这个解决方案适合文件管理器,但经过多年努力获得正确的代码,这是我最近的一个:

/**
 * Returns all available SD-Cards in the system (include emulated)
 *
 * Warning: Hack! Based on Android source code of version 4.3 (API 18)
 * Because there is no standard way to get it.
 *
 * @return paths to all available SD-Cards in the system (include emulated)
 */
public static String[] getStorageDirectories(Context pContext)
{
    // Final set of paths
    final Set<String> rv = new HashSet<>();

    //Get primary & secondary external device storage (internal storage & micro SDCARD slot...)
    File[]  listExternalDirs = ContextCompat.getExternalFilesDirs(pContext, null);
    for(int i=0;i<listExternalDirs.length;i++){
        if(listExternalDirs[i] != null) {
            String path = listExternalDirs[i].getAbsolutePath();
            int indexMountRoot = path.indexOf("/Android/data/");
            if(indexMountRoot >= 0 && indexMountRoot <= path.length()){
                //Get the root path for the external directory
                rv.add(path.substring(0, indexMountRoot));
            }
        }
    }
    return rv.toArray(new String[rv.size()]);
}

Answer 2

如果您仅使用 Android 4.0+。这里的这些答案将为您提供帮助：

如何-i-get-external-sd-card-path-for-android-4-0

答案中的一些代码示例：

public static HashSet<String> getExternalMounts() {
    final HashSet<String> out = new HashSet<String>();
    String reg = "(?i).*vold.*(vfat|ntfs|exfat|fat32|ext3|ext4).*rw.*";
    String s = "";
    try {
        final Process process = new ProcessBuilder().command("mount")
                .redirectErrorStream(true).start();
        process.waitFor();
        final InputStream is = process.getInputStream();
        final byte[] buffer = new byte[1024];
        while (is.read(buffer) != -1) {
            s = s + new String(buffer);
        }
        is.close();
    } catch (final Exception e) {
        e.printStackTrace();
    }

    // parse output
    final String[] lines = s.split("\n");
    for (String line : lines) {
        if (!line.toLowerCase(Locale.US).contains("asec")) {
            if (line.matches(reg)) {
                String[] parts = line.split(" ");
                for (String part : parts) {
                    if (part.startsWith("/"))
                        if (!part.toLowerCase(Locale.US).contains("vold"))
                            out.add(part);
                }
            }
        }
    }
    return out;
}

另一个答案在这里。

private static final Pattern DIR_SEPORATOR = Pattern.compile("/");

/**
 * Raturns all available SD-Cards in the system (include emulated)
 *
 * Warning: Hack! Based on Android source code of version 4.3 (API 18)
 * Because there is no standart way to get it.
 * TODO: Test on future Android versions 4.4+
 *
 * @return paths to all available SD-Cards in the system (include emulated)
 */
public static String[] getStorageDirectories()
{
    // Final set of paths
    final Set<String> rv = new HashSet<String>();
    // Primary physical SD-CARD (not emulated)
    final String rawExternalStorage = System.getenv("EXTERNAL_STORAGE");
    // All Secondary SD-CARDs (all exclude primary) separated by ":"
    final String rawSecondaryStoragesStr = System.getenv("SECONDARY_STORAGE");
    // Primary emulated SD-CARD
    final String rawEmulatedStorageTarget = System.getenv("EMULATED_STORAGE_TARGET");
    if(TextUtils.isEmpty(rawEmulatedStorageTarget))
    {
        // Device has physical external storage; use plain paths.
        if(TextUtils.isEmpty(rawExternalStorage))
        {
            // EXTERNAL_STORAGE undefined; falling back to default.
            rv.add("/storage/sdcard0");
        }
        else
        {
            rv.add(rawExternalStorage);
        }
    }
    else
    {
        // Device has emulated storage; external storage paths should have
        // userId burned into them.
        final String rawUserId;
        if(Build.VERSION.SDK_INT < Build.VERSION_CODES.JELLY_BEAN_MR1)
        {
            rawUserId = "";
        }
        else
        {
            final String path = Environment.getExternalStorageDirectory().getAbsolutePath();
            final String[] folders = DIR_SEPORATOR.split(path);
            final String lastFolder = folders[folders.length - 1];
            boolean isDigit = false;
            try
            {
                Integer.valueOf(lastFolder);
                isDigit = true;
            }
            catch(NumberFormatException ignored)
            {
            }
            rawUserId = isDigit ? lastFolder : "";
        }
        // /storage/emulated/0[1,2,...]
        if(TextUtils.isEmpty(rawUserId))
        {
            rv.add(rawEmulatedStorageTarget);
        }
        else
        {
            rv.add(rawEmulatedStorageTarget + File.separator + rawUserId);
        }
    }
    // Add all secondary storages
    if(!TextUtils.isEmpty(rawSecondaryStoragesStr))
    {
        // All Secondary SD-CARDs splited into array
        final String[] rawSecondaryStorages = rawSecondaryStoragesStr.split(File.pathSeparator);
        Collections.addAll(rv, rawSecondaryStorages);
    }
    return rv.toArray(new String[rv.size()]);
}

第三个答案是：

final String state = Environment.getExternalStorageState();

if ( Environment.MEDIA_MOUNTED.equals(state) || Environment.MEDIA_MOUNTED_READ_ONLY.equals(state) ) {  // we can read the External Storage...           
    //Retrieve the primary External Storage:
    final File primaryExternalStorage = Environment.getExternalStorageDirectory();

    //Retrieve the External Storages root directory:
    final String externalStorageRootDir;
    if ( (externalStorageRootDir = primaryExternalStorage.getParent()) == null ) {  // no parent...
        Log.d(TAG, "External Storage: " + primaryExternalStorage + "\n");
    }
    else {
        final File externalStorageRoot = new File( externalStorageRootDir );
        final File[] files = externalStorageRoot.listFiles();

        for ( final File file : files ) {
            if ( file.isDirectory() && file.canRead() && (file.listFiles().length > 0) ) {  // it is a real directory (not a USB drive)...
                Log.d(TAG, "External Storage: " + file.getAbsolutePath() + "\n");
            }
        }
    }
}