Android多机型SD卡路径获取问题求助（参考assif_tiger相关讨论）

Hey there! I’ve fought this exact battle before—getting consistent SD card paths across the chaos of Android devices is such a pain, especially with manufacturers constantly deviating from "standard" paths post Android 6.0. Let’s walk through a solid, device-agnostic solution that should cover most scenarios:

First rule of thumb: never rely on paths like /sdcard/ or /storage/sdcard1/. Different brands (looking at you, Samsung, Xiaomi, Huawei) love to rename these, and newer Android versions use UUID-based paths like /storage/XXXX-XXXX/ for external storage. Always go through system-provided methods.

A. Prioritize Storage Access Framework (SAF) for Android 5.0+ #

SAF is Google’s official way to handle storage across devices, and it’s mandatory for Android 10+ (thanks to scoped storage). It lets users pick the storage location, and you interact with it via URIs instead of raw paths—no more guessing where the SD card is.

Here’s a quick snippet to kick off the SAF intent:

// In your activity/fragment
private static final int REQUEST_CODE_SAF = 100;

public void openSAF() {
    Intent intent = new Intent(Intent.ACTION_OPEN_DOCUMENT_TREE);
    intent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
    intent.addFlags(Intent.FLAG_GRANT_WRITE_URI_PERMISSION);
    intent.addFlags(Intent.FLAG_GRANT_PERSISTABLE_URI_PERMISSION);
    startActivityForResult(intent, REQUEST_CODE_SAF);
}

// Handle the result
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    if (requestCode == REQUEST_CODE_SAF && resultCode == RESULT_OK) {
        Uri treeUri = data.getData();
        // Persist the permission so it survives app restarts
        getContentResolver().takePersistableUriPermission(treeUri,
                Intent.FLAG_GRANT_READ_URI_PERMISSION | Intent.FLAG_GRANT_WRITE_URI_PERMISSION);
        // Now you can use this Uri to read/write files via ContentResolver
    }
}

B. Fallback for Older Devices (Pre-Android 5.0) #

For older versions, you can scan the /storage/ directory for valid removable storage, but you need to filter out internal storage and invalid paths:

public List<String> getLegacySDCardPaths() {
    List<String> validPaths = new ArrayList<>();
    File storageRoot = new File("/storage/");
    if (!storageRoot.exists() || !storageRoot.isDirectory()) {
        return validPaths;
    }

    File[] storageDirs = storageRoot.listFiles();
    if (storageDirs == null) {
        return validPaths;
    }

    String internalStoragePath = Environment.getExternalStorageDirectory().getAbsolutePath();
    for (File dir : storageDirs) {
        if (dir.isDirectory() && !dir.getAbsolutePath().equals(internalStoragePath)) {
            // Check if we can write to this path
            if (isPathWritable(dir.getAbsolutePath())) {
                validPaths.add(dir.getAbsolutePath());
            }
        }
    }

    // Add the default external storage if it's removable
    if (Environment.isExternalStorageRemovable()) {
        validPaths.add(internalStoragePath);
    }

    return validPaths;
}

private boolean isPathWritable(String path) {
    File testFile = new File(path, "temp_test_file.tmp");
    try {
        if (testFile.createNewFile()) {
            testFile.delete();
            return true;
        }
    } catch (IOException e) {
        // Log the error if needed
    }
    return false;
}

C. Validate Every Path #

No matter which method you use, always verify that the path is actually writable (or readable, depending on your needs). The isPathWritable method above does this by trying to create a temporary file—if it works, the path is valid.

• Runtime Permissions: For Android 6.0+, you need to request READ_EXTERNAL_STORAGE and WRITE_EXTERNAL_STORAGE dynamically before accessing storage. Don’t forget to handle the permission request result.
• Scoped Storage (Android 10+): Direct file path access is blocked here, so SAF is your only reliable option. Trying to use raw paths will throw exceptions.
• Multiple SD Cards: Some devices support multiple external storage slots—make sure your code iterates through all valid volumes instead of just picking the first one.

内容的提问来源于stack exchange，提问作者Boosuro