অপসারণযোগ্য এসডি কার্ড খুঁজতে আমি যে পদ্ধতিটি ব্যবহার করি তা এখানে । এটি জটিল, এবং সম্ভবত কিছু পরিস্থিতিতে ওভারকিল, তবে এটি গত কয়েক বছর ধরে আমি পরীক্ষিত বিভিন্ন অ্যান্ড্রয়েড সংস্করণ এবং ডিভাইস প্রস্তুতকারকের উপর কাজ করে। আমি এমন কোনও ডিভাইস সম্পর্কে জানি না যে এপিআই স্তর 15 এর পরে এটিতে এসডি কার্ডটি খুঁজে পাওয়া যায় না, যদি কোনও মাউন্ট থাকে তবে। এটি বেশিরভাগ ক্ষেত্রেই মিথ্যা ইতিবাচক প্রত্যাবর্তন করবে না, বিশেষত যদি আপনি এটির জন্য কোনও পরিচিত ফাইলের নাম দেন।
আপনি যদি এমন কোনও ক্ষেত্রে কাজ করেন না তবে দয়া করে আমাকে জানান।
import android.content.Context;
import android.os.Build;
import android.os.Environment;
import android.support.v4.content.ContextCompat;
import android.text.TextUtils;
import android.util.Log;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.LinkedHashSet;
import java.util.Locale;
import java.util.regex.Pattern;
public class SDCard {
private static final String TAG = "SDCard";
/** In some scenarios we can expect to find a specified file or folder on SD cards designed
* to work with this app. If so, set KNOWNFILE to that filename. It will make our job easier.
* Set it to null otherwise. */
private static final String KNOWNFILE = null;
/** Common paths for microSD card. **/
private static String[] commonPaths = {
// Some of these taken from
// /programming/13976982/removable-storage-external-sdcard-path-by-manufacturers
// These are roughly in order such that the earlier ones, if they exist, are more sure
// to be removable storage than the later ones.
"/mnt/Removable/MicroSD",
"/storage/removable/sdcard1", // !< Sony Xperia Z1
"/Removable/MicroSD", // Asus ZenPad C
"/removable/microsd",
"/external_sd", // Samsung
"/_ExternalSD", // some LGs
"/storage/extSdCard", // later Samsung
"/storage/extsdcard", // Main filesystem is case-sensitive; FAT isn't.
"/mnt/extsd", // some Chinese tablets, e.g. Zeki
"/storage/sdcard1", // If this exists it's more likely than sdcard0 to be removable.
"/mnt/extSdCard",
"/mnt/sdcard/external_sd",
"/mnt/external_sd",
"/storage/external_SD",
"/storage/ext_sd", // HTC One Max
"/mnt/sdcard/_ExternalSD",
"/mnt/sdcard-ext",
"/sdcard2", // HTC One M8s
"/sdcard1", // Sony Xperia Z
"/mnt/media_rw/sdcard1", // 4.4.2 on CyanogenMod S3
"/mnt/sdcard", // This can be built-in storage (non-removable).
"/sdcard",
"/storage/sdcard0",
"/emmc",
"/mnt/emmc",
"/sdcard/sd",
"/mnt/sdcard/bpemmctest",
"/mnt/external1",
"/data/sdext4",
"/data/sdext3",
"/data/sdext2",
"/data/sdext",
"/storage/microsd" //ASUS ZenFone 2
// If we ever decide to support USB OTG storage, the following paths could be helpful:
// An LG Nexus 5 apparently uses usb://1002/UsbStorage/ as a URI to access an SD
// card over OTG cable. Other models, like Galaxy S5, use /storage/UsbDriveA
// "/mnt/usb_storage",
// "/mnt/UsbDriveA",
// "/mnt/UsbDriveB",
};
/** Find path to removable SD card. */
public static File findSdCardPath(Context context) {
String[] mountFields;
BufferedReader bufferedReader = null;
String lineRead = null;
/** Possible SD card paths */
LinkedHashSet<File> candidatePaths = new LinkedHashSet<>();
/** Build a list of candidate paths, roughly in order of preference. That way if
* we can't definitively detect removable storage, we at least can pick a more likely
* candidate. */
// Could do: use getExternalStorageState(File path), with and without an argument, when
// available. With an argument is available since API level 21.
// This may not be necessary, since we also check whether a directory exists and has contents,
// which would fail if the external storage state is neither MOUNTED nor MOUNTED_READ_ONLY.
// I moved hard-coded paths toward the end, but we need to make sure we put the ones in
// backwards order that are returned by the OS. And make sure the iterators respect
// the order!
// This is because when multiple "external" storage paths are returned, it's always (in
// experience, but not guaranteed by documentation) with internal/emulated storage
// first, removable storage second.
// Add value of environment variables as candidates, if set:
// EXTERNAL_STORAGE, SECONDARY_STORAGE, EXTERNAL_SDCARD_STORAGE
// But note they are *not* necessarily *removable* storage! Especially EXTERNAL_STORAGE.
// And they are not documented (API) features. Typically useful only for old versions of Android.
String val = System.getenv("SECONDARY_STORAGE");
if (!TextUtils.isEmpty(val)) addPath(val, null, candidatePaths);
val = System.getenv("EXTERNAL_SDCARD_STORAGE");
if (!TextUtils.isEmpty(val)) addPath(val, null, candidatePaths);
// Get listing of mounted devices with their properties.
ArrayList<File> mountedPaths = new ArrayList<>();
try {
// Note: Despite restricting some access to /proc (http://stackoverflow.com/a/38728738/423105),
// Android 7.0 does *not* block access to /proc/mounts, according to our test on George's Alcatel A30 GSM.
bufferedReader = new BufferedReader(new FileReader("/proc/mounts"));
// Iterate over each line of the mounts listing.
while ((lineRead = bufferedReader.readLine()) != null) {
Log.d(TAG, "\nMounts line: " + lineRead);
mountFields = lineRead.split(" ");
// columns: device, mountpoint, fs type, options... Example:
// /dev/block/vold/179:97 /storage/sdcard1 vfat rw,dirsync,nosuid,nodev,noexec,relatime,uid=1000,gid=1015,fmask=0002,dmask=0002,allow_utime=0020,codepage=cp437,iocharset=iso8859-1,shortname=mixed,utf8,errors=remount-ro 0 0
String device = mountFields[0], path = mountFields[1], fsType = mountFields[2];
// The device, path, and fs type must conform to expected patterns.
if (!(devicePattern.matcher(device).matches() &&
pathPattern.matcher(path).matches() &&
fsTypePattern.matcher(fsType).matches()) ||
// mtdblock is internal, I'm told.
device.contains("mtdblock") ||
// Check for disqualifying patterns in the path.
pathAntiPattern.matcher(path).matches()) {
// If this mounts line fails our tests, skip it.
continue;
}
// TODO maybe: check options to make sure it's mounted RW?
// The answer at http://stackoverflow.com/a/13648873/423105 does.
// But it hasn't seemed to be necessary so far in my testing.
// This line met the criteria so far, so add it to candidate list.
addPath(path, null, mountedPaths);
}
} catch (IOException ignored) {
} finally {
if (bufferedReader != null) {
try {
bufferedReader.close();
} catch (IOException ignored) {
}
}
}
// Append the paths from mount table to candidate list, in reverse order.
if (!mountedPaths.isEmpty()) {
// See https://stackoverflow.com/a/5374346/423105 on why the following is necessary.
// Basically, .toArray() needs its parameter to know what type of array to return.
File[] mountedPathsArray = mountedPaths.toArray(new File[mountedPaths.size()]);
addAncestors(candidatePaths, mountedPathsArray);
}
// Add hard-coded known common paths to candidate list:
addStrings(candidatePaths, commonPaths);
// If the above doesn't work we could try the following other options, but in my experience they
// haven't added anything helpful yet.
// getExternalFilesDir() and getExternalStorageDirectory() typically something app-specific like
// /storage/sdcard1/Android/data/com.mybackuparchives.android/files
// so we want the great-great-grandparent folder.
// This may be non-removable.
Log.d(TAG, "Environment.getExternalStorageDirectory():");
addPath(null, ancestor(Environment.getExternalStorageDirectory()), candidatePaths);
// Context.getExternalFilesDirs() is only available from API level 19. You can use
// ContextCompat.getExternalFilesDirs() on earlier APIs, but it only returns one dir anyway.
Log.d(TAG, "context.getExternalFilesDir(null):");
addPath(null, ancestor(context.getExternalFilesDir(null)), candidatePaths);
// "Returns absolute paths to application-specific directories on all external storage
// devices where the application can place persistent files it owns."
// We might be able to use these to deduce a higher-level folder that isn't app-specific.
// Also, we apparently have to call getExternalFilesDir[s](), at least in KITKAT+, in order to ensure that the
// "external files" directory exists and is available.
Log.d(TAG, "ContextCompat.getExternalFilesDirs(context, null):");
addAncestors(candidatePaths, ContextCompat.getExternalFilesDirs(context, null));
// Very similar results:
Log.d(TAG, "ContextCompat.getExternalCacheDirs(context):");
addAncestors(candidatePaths, ContextCompat.getExternalCacheDirs(context));
// TODO maybe: use getExternalStorageState(File path), with and without an argument, when
// available. With an argument is available since API level 21.
// This may not be necessary, since we also check whether a directory exists,
// which would fail if the external storage state is neither MOUNTED nor MOUNTED_READ_ONLY.
// A "public" external storage directory. But in my experience it doesn't add anything helpful.
// Note that you can't pass null, or you'll get an NPE.
final File publicDirectory = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_MUSIC);
// Take the parent, because we tend to get a path like /pathTo/sdCard/Music.
addPath(null, publicDirectory.getParentFile(), candidatePaths);
// EXTERNAL_STORAGE: may not be removable.
val = System.getenv("EXTERNAL_STORAGE");
if (!TextUtils.isEmpty(val)) addPath(val, null, candidatePaths);
if (candidatePaths.isEmpty()) {
Log.w(TAG, "No removable microSD card found.");
return null;
} else {
Log.i(TAG, "\nFound potential removable storage locations: " + candidatePaths);
}
// Accept or eliminate candidate paths if we can determine whether they're removable storage.
// In Lollipop and later, we can check isExternalStorageRemovable() status on each candidate.
if (Build.VERSION.SDK_INT >= 21) {
Iterator<File> itf = candidatePaths.iterator();
while (itf.hasNext()) {
File dir = itf.next();
// handle illegalArgumentException if the path is not a valid storage device.
try {
if (Environment.isExternalStorageRemovable(dir)
// && containsKnownFile(dir)
) {
Log.i(TAG, dir.getPath() + " is removable external storage");
return dir;
} else if (Environment.isExternalStorageEmulated(dir)) {
Log.d(TAG, "Removing emulated external storage dir " + dir);
itf.remove();
}
} catch (IllegalArgumentException e) {
Log.d(TAG, "isRemovable(" + dir.getPath() + "): not a valid storage device.", e);
}
}
}
// Continue trying to accept or eliminate candidate paths based on whether they're removable storage.
// On pre-Lollipop, we only have singular externalStorage. Check whether it's removable.
if (Build.VERSION.SDK_INT >= 9) {
File externalStorage = Environment.getExternalStorageDirectory();
Log.d(TAG, String.format(Locale.ROOT, "findSDCardPath: getExternalStorageDirectory = %s", externalStorage.getPath()));
if (Environment.isExternalStorageRemovable()) {
// Make sure this is a candidate.
// TODO: Does this contains() work? Should we be canonicalizing paths before comparing?
if (candidatePaths.contains(externalStorage)
// && containsKnownFile(externalStorage)
) {
Log.d(TAG, "Using externalStorage dir " + externalStorage);
return externalStorage;
}
} else if (Build.VERSION.SDK_INT >= 11 && Environment.isExternalStorageEmulated()) {
Log.d(TAG, "Removing emulated external storage dir " + externalStorage);
candidatePaths.remove(externalStorage);
}
}
// If any directory contains our special test file, consider that the microSD card.
if (KNOWNFILE != null) {
for (File dir : candidatePaths) {
Log.d(TAG, String.format(Locale.ROOT, "findSdCardPath: Looking for known file in candidate path, %s", dir));
if (containsKnownFile(dir)) return dir;
}
}
// If we don't find the known file, still try taking the first candidate.
if (!candidatePaths.isEmpty()) {
Log.d(TAG, "No definitive path to SD card; taking the first realistic candidate.");
return candidatePaths.iterator().next();
}
// If no reasonable path was found, give up.
return null;
}
/** Add each path to the collection. */
private static void addStrings(LinkedHashSet<File> candidatePaths, String[] newPaths) {
for (String path : newPaths) {
addPath(path, null, candidatePaths);
}
}
/** Add ancestor of each File to the collection. */
private static void addAncestors(LinkedHashSet<File> candidatePaths, File[] files) {
for (int i = files.length - 1; i >= 0; i--) {
addPath(null, ancestor(files[i]), candidatePaths);
}
}
/**
* Add a new candidate directory path to our list, if it's not obviously wrong.
* Supply path as either String or File object.
* @param strNew path of directory to add (or null)
* @param fileNew directory to add (or null)
*/
private static void addPath(String strNew, File fileNew, Collection<File> paths) {
// If one of the arguments is null, fill it in from the other.
if (strNew == null) {
if (fileNew == null) return;
strNew = fileNew.getPath();
} else if (fileNew == null) {
fileNew = new File(strNew);
}
if (!paths.contains(fileNew) &&
// Check for paths known not to be removable SD card.
// The antipattern check can be redundant, depending on where this is called from.
!pathAntiPattern.matcher(strNew).matches()) {
// Eliminate candidate if not a directory or not fully accessible.
if (fileNew.exists() && fileNew.isDirectory() && fileNew.canExecute()) {
Log.d(TAG, " Adding candidate path " + strNew);
paths.add(fileNew);
} else {
Log.d(TAG, String.format(Locale.ROOT, " Invalid path %s: exists: %b isDir: %b canExec: %b canRead: %b",
strNew, fileNew.exists(), fileNew.isDirectory(), fileNew.canExecute(), fileNew.canRead()));
}
}
}
private static final String ANDROID_DIR = File.separator + "Android";
private static File ancestor(File dir) {
// getExternalFilesDir() and getExternalStorageDirectory() typically something app-specific like
// /storage/sdcard1/Android/data/com.mybackuparchives.android/files
// so we want the great-great-grandparent folder.
if (dir == null) {
return null;
} else {
String path = dir.getAbsolutePath();
int i = path.indexOf(ANDROID_DIR);
if (i == -1) {
return dir;
} else {
return new File(path.substring(0, i));
}
}
}
/** Returns true iff dir contains the special test file.
* Assumes that dir exists and is a directory. (Is this a necessary assumption?) */
private static boolean containsKnownFile(File dir) {
if (KNOWNFILE == null) return false;
File knownFile = new File(dir, KNOWNFILE);
return knownFile.exists();
}
private static Pattern
/** Pattern that SD card device should match */
devicePattern = Pattern.compile("/dev/(block/.*vold.*|fuse)|/mnt/.*"),
/** Pattern that SD card mount path should match */
pathPattern = Pattern.compile("/(mnt|storage|external_sd|extsd|_ExternalSD|Removable|.*MicroSD).*",
Pattern.CASE_INSENSITIVE),
/** Pattern that the mount path should not match.
* 'emulated' indicates an internal storage location, so skip it.
* 'asec' is an encrypted package file, decrypted and mounted as a directory. */
pathAntiPattern = Pattern.compile(".*(/secure|/asec|/emulated).*"),
/** These are expected fs types, including vfat. tmpfs is not OK.
* fuse can be removable SD card (as on Moto E or Asus ZenPad), or can be internal (Huawei G610). */
fsTypePattern = Pattern.compile(".*(fat|msdos|ntfs|ext[34]|fuse|sdcard|esdfs).*");
}
পুনশ্চ
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />ম্যানিফেস্টে ভুলে যাবেন না । এবং এপিআই স্তরের 23 এবং উচ্চতর সময়ে, checkSelfPermission/requestPermissions ।- আপনি এসডি কার্ডে খুঁজে পাওয়ার আশা করছেন এমন কোনও ফাইল বা ফোল্ডার যদি থাকে তবে KNOWNFILE = "মায়াপফল" সেট করুন। এটি সনাক্তকরণকে আরও সঠিক করে তোলে।
- অবশ্যই আপনি এর মান ক্যাশে করতে চান
findSdCardPath(), প্রতিটি বার যখন এটি প্রয়োজন তখন এটির পুনর্নির্মাণের চেয়ে ।
- উপরের কোডটিতে লগিংয়ের একটি গুচ্ছ রয়েছে
Log.d()। এটি সঠিক ক্ষেত্রে খুঁজে পাওয়া যায় না এমন কোনও ক্ষেত্রে নির্ণয় করতে সহায়তা করে। আপনি লগিং করতে না চাইলে এটি মন্তব্য করুন।