Skip to content

Most visited

Recently visited

navigation

StorageManager

public class StorageManager
extends Object

java.lang.Object
   ↳ android.os.storage.StorageManager


StorageManager is the interface to the systems storage service. The storage manager handles storage-related items such as Opaque Binary Blobs (OBBs).

OBBs contain a filesystem that maybe be encrypted on disk and mounted on-demand from an application. OBBs are a good way of providing large amounts of binary assets without packaging them into APKs as they may be multiple gigabytes in size. However, due to their size, they're most likely stored in a shared storage pool accessible from all programs. The system does not guarantee the security of the OBB file itself: if any program modifies the OBB, there is no guarantee that a read from that OBB will produce the expected output.

Instances of this class must be obtained using Context.getSystemService(Class) with the argument StorageManager.class or Context.getSystemService(String) with the argument Context.STORAGE_SERVICE.

Summary

Constants

String ACTION_MANAGE_STORAGE

Activity Action: Allows the user to manage their storage.

String EXTRA_REQUESTED_BYTES

Extra used to indicate the total size (in bytes) that an application is interested in allocating.

String EXTRA_UUID

Extra UUID used to indicate the storage volume where an application is interested in allocating or managing disk space.

Fields

public static final UUID UUID_DEFAULT

UUID representing the default internal storage of this device which provides getDataDirectory().

Public methods

void allocateBytes(FileDescriptor fd, long bytes)

Allocate the requested number of bytes for your application to use in the given open file.

void allocateBytes(UUID storageUuid, long bytes)

Allocate the requested number of bytes for your application to use on the given storage volume.

long getAllocatableBytes(UUID storageUuid)

Return the maximum number of new bytes that your app can allocate for itself on the given storage volume.

long getCacheQuotaBytes(UUID storageUuid)

Return quota size in bytes for all cached data belonging to the calling app on the given storage volume.

long getCacheSizeBytes(UUID storageUuid)

Return total size in bytes of all cached data belonging to the calling app on the given storage volume.

String getMountedObbPath(String rawPath)

Check the mounted path of an Opaque Binary Blob (OBB) file.

StorageVolume getPrimaryStorageVolume()

Return the primary shared/external storage volume available to the current user.

StorageVolume getStorageVolume(File file)

Return the StorageVolume that contains the given file, or null if none.

List<StorageVolume> getStorageVolumes()

Return the list of shared/external storage volumes available to the current user.

UUID getUuidForPath(File path)

Return a UUID identifying the storage volume that hosts the given filesystem path.

boolean isCacheBehaviorGroup(File path)

Read the current value set by setCacheBehaviorGroup(File, boolean).

boolean isCacheBehaviorTombstone(File path)

Read the current value set by setCacheBehaviorTombstone(File, boolean).

boolean isEncrypted(File file)

Return if data stored at or under the given path will be encrypted while at rest.

boolean isObbMounted(String rawPath)

Check whether an Opaque Binary Blob (OBB) is mounted or not.

boolean mountObb(String rawPath, String key, OnObbStateChangeListener listener)

Mount an Opaque Binary Blob (OBB) file.

ParcelFileDescriptor openProxyFileDescriptor(int mode, ProxyFileDescriptorCallback callback, Handler handler)

Opens a seekable ParcelFileDescriptor that proxies all low-level I/O requests back to the given ProxyFileDescriptorCallback.

void setCacheBehaviorGroup(File path, boolean group)

Enable or disable special cache behavior that treats this directory and its contents as an entire group.

void setCacheBehaviorTombstone(File path, boolean tombstone)

Enable or disable special cache behavior that leaves deleted cache files intact as tombstones.

boolean unmountObb(String rawPath, boolean force, OnObbStateChangeListener listener)

Unmount an Opaque Binary Blob (OBB) file asynchronously.

Inherited methods

From class java.lang.Object

Constants

ACTION_MANAGE_STORAGE

added in API level 25
String ACTION_MANAGE_STORAGE

Activity Action: Allows the user to manage their storage. This activity provides the ability to free up space on the device by deleting data such as apps.

If the sending application has a specific storage device or allocation size in mind, they can optionally define EXTRA_UUID or EXTRA_REQUESTED_BYTES, respectively.

This intent should be launched using startActivityForResult(Intent, int) so that the user knows which app is requesting the storage space. The returned result will be RESULT_OK if the requested space was made available, or RESULT_CANCELED otherwise.

Constant Value: "android.os.storage.action.MANAGE_STORAGE"

EXTRA_REQUESTED_BYTES

added in API level 26
String EXTRA_REQUESTED_BYTES

Extra used to indicate the total size (in bytes) that an application is interested in allocating.

When defined, the management UI will help guide the user to free up enough disk space to reach this requested value.

See also:

Constant Value: "android.os.storage.extra.REQUESTED_BYTES"

EXTRA_UUID

added in API level 26
String EXTRA_UUID

Extra UUID used to indicate the storage volume where an application is interested in allocating or managing disk space.

See also:

Constant Value: "android.os.storage.extra.UUID"

Fields

UUID_DEFAULT

added in API level 26
UUID UUID_DEFAULT

UUID representing the default internal storage of this device which provides getDataDirectory().

This value is constant across all devices and it will never change, and thus it cannot be used to uniquely identify a particular physical device.

See also:

Public methods

allocateBytes

added in API level 26
void allocateBytes (FileDescriptor fd, 
                long bytes)

Allocate the requested number of bytes for your application to use in the given open file. This will cause the system to delete any cached files necessary to satisfy your request.

Attempts to allocate disk space beyond the value returned by ERROR(/#getAllocatableBytes(UUID, int)) will fail.

This method guarantees that bytes have been allocated to the opened file, otherwise it will throw if fast allocation is not possible. Fast allocation is typically only supported in private app data directories, and on shared/external storage devices which are emulated.

If you're progressively allocating an unbounded amount of storage space (such as when recording a video) you should avoid calling this method more than once every 60 seconds.

This method may take several seconds to complete, so it should only be called from a worker thread.

Parameters
fd FileDescriptor: the open file that you'd like to allocate disk space for.

bytes long: the number of bytes to allocate. This is the desired final size of the open file. If the open file is smaller than this requested size, it will be extended without modifying any existing contents. If the open file is larger than this requested size, it will be truncated.

Value is a non-negative number of bytes.

Throws
IOException when the storage device isn't present, or when it doesn't support allocating space, or if the device had trouble allocating the requested space.

See also:

allocateBytes

added in API level 26
void allocateBytes (UUID storageUuid, 
                long bytes)

Allocate the requested number of bytes for your application to use on the given storage volume. This will cause the system to delete any cached files necessary to satisfy your request.

Attempts to allocate disk space beyond the value returned by ERROR(/#getAllocatableBytes(UUID, int)) will fail.

Since multiple apps can be running simultaneously, this method may be subject to race conditions. If possible, consider using ERROR(/#allocateBytes(FileDescriptor, long, int)) which will guarantee that bytes are allocated to an opened file.

If you're progressively allocating an unbounded amount of storage space (such as when recording a video) you should avoid calling this method more than once every 60 seconds.

This method may take several seconds to complete, so it should only be called from a worker thread.

Parameters
storageUuid UUID: the UUID of the storage volume where you'd like to allocate disk space. The UUID for a specific path can be obtained using getUuidForPath(File).

This value must never be null.

bytes long: the number of bytes to allocate.

Value is a non-negative number of bytes.

Throws
IOException when the storage device isn't present, or when it doesn't support allocating space, or if the device had trouble allocating the requested space.

See also:

getAllocatableBytes

added in API level 26
long getAllocatableBytes (UUID storageUuid)

Return the maximum number of new bytes that your app can allocate for itself on the given storage volume. This value is typically larger than getUsableSpace(), since the system may be willing to delete cached files to satisfy an allocation request. You can then allocate space for yourself using ERROR(/#allocateBytes(UUID, long, int)) or ERROR(/#allocateBytes(FileDescriptor, long, int)).

This method is best used as a pre-flight check, such as deciding if there is enough space to store an entire music album before you allocate space for each audio file in the album. Attempts to allocate disk space beyond the returned value will fail.

If the returned value is not large enough for the data you'd like to persist, you can launch ACTION_MANAGE_STORAGE with the EXTRA_UUID and EXTRA_REQUESTED_BYTES options to help involve the user in freeing up disk space.

If you're progressively allocating an unbounded amount of storage space (such as when recording a video) you should avoid calling this method more than once every 30 seconds.

Note: if your app uses the android:sharedUserId manifest feature, then allocatable space for all packages in your shared UID is tracked together as a single unit.

This method may take several seconds to complete, so it should only be called from a worker thread.

Value is a non-negative number of bytes.

Parameters
storageUuid UUID: the UUID of the storage volume where you're considering allocating disk space, since allocatable space can vary widely depending on the underlying storage device. The UUID for a specific path can be obtained using getUuidForPath(File).

This value must never be null.

Returns
long the maximum number of new bytes that the calling app can allocate using ERROR(/#allocateBytes(UUID, long, int)) or ERROR(/#allocateBytes(FileDescriptor, long, int)).

Value is a non-negative number of bytes.

Throws
IOException when the storage device isn't present, or when it doesn't support allocating space.

getCacheQuotaBytes

added in API level 26
long getCacheQuotaBytes (UUID storageUuid)

Return quota size in bytes for all cached data belonging to the calling app on the given storage volume.

If your app goes above this quota, your cached files will be some of the first to be deleted when additional disk space is needed. Conversely, if your app stays under this quota, your cached files will be some of the last to be deleted when additional disk space is needed.

This quota will change over time depending on how frequently the user interacts with your app, and depending on how much system-wide disk space is used.

Note: if your app uses the android:sharedUserId manifest feature, then cached data for all packages in your shared UID is tracked together as a single unit.

This method may take several seconds to complete, so it should only be called from a worker thread.

Value is a non-negative number of bytes.

Parameters
storageUuid UUID: the UUID of the storage volume that you're interested in. The UUID for a specific path can be obtained using getUuidForPath(File).

This value must never be null.

Returns
long

Value is a non-negative number of bytes.

Throws
IOException when the storage device isn't present, or when it doesn't support cache quotas.

See also:

getCacheSizeBytes

added in API level 26
long getCacheSizeBytes (UUID storageUuid)

Return total size in bytes of all cached data belonging to the calling app on the given storage volume.

Cached data tracked by this method always includes getCacheDir() and getCodeCacheDir(), and it also includes getExternalCacheDir() if the primary shared/external storage is hosted on the same storage device as your private data.

Note: if your app uses the android:sharedUserId manifest feature, then cached data for all packages in your shared UID is tracked together as a single unit.

This method may take several seconds to complete, so it should only be called from a worker thread.

Value is a non-negative number of bytes.

Parameters
storageUuid UUID: the UUID of the storage volume that you're interested in. The UUID for a specific path can be obtained using getUuidForPath(File).

This value must never be null.

Returns
long

Value is a non-negative number of bytes.

Throws
IOException when the storage device isn't present, or when it doesn't support cache quotas.

See also:

getMountedObbPath

added in API level 9
String getMountedObbPath (String rawPath)

Check the mounted path of an Opaque Binary Blob (OBB) file. This will give you the path to where you can obtain access to the internals of the OBB.

Parameters
rawPath String: path to OBB image

Returns
String absolute path to mounted OBB image data or null if not mounted or exception encountered trying to read status

getPrimaryStorageVolume

added in API level 24
StorageVolume getPrimaryStorageVolume ()

Return the primary shared/external storage volume available to the current user. This volume is the same storage device returned by getExternalStorageDirectory() and getExternalFilesDir(String).

Returns
StorageVolume

This value will never be null.

getStorageVolume

added in API level 24
StorageVolume getStorageVolume (File file)

Return the StorageVolume that contains the given file, or null if none.

Parameters
file File

Returns
StorageVolume

This value may be null.

getStorageVolumes

added in API level 24
List<StorageVolume> getStorageVolumes ()

Return the list of shared/external storage volumes available to the current user. This includes both the primary shared storage device and any attached external volumes including SD cards and USB drives.

Returns
List<StorageVolume>

This value will never be null.

See also:

getUuidForPath

added in API level 26
UUID getUuidForPath (File path)

Return a UUID identifying the storage volume that hosts the given filesystem path.

If this path is hosted by the default internal storage of the device at getDataDirectory(), the returned value will be UUID_DEFAULT.

Parameters
path File

This value must never be null.

Returns
UUID

This value will never be null.

Throws
IOException when the storage device at the given path isn't present, or when it doesn't have a valid UUID.

isCacheBehaviorGroup

added in API level 26
boolean isCacheBehaviorGroup (File path)

Read the current value set by setCacheBehaviorGroup(File, boolean).

Parameters
path File

Returns
boolean

Throws
IOException

isCacheBehaviorTombstone

added in API level 26
boolean isCacheBehaviorTombstone (File path)

Read the current value set by setCacheBehaviorTombstone(File, boolean).

Parameters
path File

Returns
boolean

Throws
IOException

isEncrypted

added in API level 24
boolean isEncrypted (File file)

Return if data stored at or under the given path will be encrypted while at rest. This can help apps avoid the overhead of double-encrypting data.

Parameters
file File

Returns
boolean

isObbMounted

added in API level 9
boolean isObbMounted (String rawPath)

Check whether an Opaque Binary Blob (OBB) is mounted or not.

Parameters
rawPath String: path to OBB image

Returns
boolean true if OBB is mounted; false if not mounted or on error

mountObb

added in API level 9
boolean mountObb (String rawPath, 
                String key, 
                OnObbStateChangeListener listener)

Mount an Opaque Binary Blob (OBB) file. If a key is specified, it is supplied to the mounting process to be used in any encryption used in the OBB.

The OBB will remain mounted for as long as the StorageManager reference is held by the application. As soon as this reference is lost, the OBBs in use will be unmounted. The OnObbStateChangeListener registered with this call will receive the success or failure of this operation.

Note: you can only mount OBB files for which the OBB tag on the file matches a package ID that is owned by the calling program's UID. That is, shared UID applications can attempt to mount any other application's OBB that shares its UID.

Parameters
rawPath String: the path to the OBB file

key String: secret used to encrypt the OBB; may be null if no encryption was used on the OBB.

listener OnObbStateChangeListener: will receive the success or failure of the operation

Returns
boolean whether the mount call was successfully queued or not

openProxyFileDescriptor

added in API level 26
ParcelFileDescriptor openProxyFileDescriptor (int mode, 
                ProxyFileDescriptorCallback callback, 
                Handler handler)

Opens a seekable ParcelFileDescriptor that proxies all low-level I/O requests back to the given ProxyFileDescriptorCallback.

This can be useful when you want to provide quick access to a large file that isn't backed by a real file on disk, such as a file on a network share, cloud storage service, etc. As an example, you could respond to a openFileDescriptor(android.net.Uri, String) request by returning a ParcelFileDescriptor created with this method, and then stream the content on-demand as requested.

Another useful example might be where you have an encrypted file that you're willing to decrypt on-demand, but where you want to avoid persisting the cleartext version.

Parameters
mode int: The desired access mode, must be one of MODE_READ_ONLY, MODE_WRITE_ONLY, or MODE_READ_WRITE

callback ProxyFileDescriptorCallback: Callback to process file operation requests issued on returned file descriptor.

handler Handler: Handler that invokes callback methods.

Returns
ParcelFileDescriptor Seekable ParcelFileDescriptor.

This value will never be null.

Throws
IOException

setCacheBehaviorGroup

added in API level 26
void setCacheBehaviorGroup (File path, 
                boolean group)

Enable or disable special cache behavior that treats this directory and its contents as an entire group.

When enabled and this directory is considered for automatic deletion by the OS, all contained files will either be deleted together, or not at all. This is useful when you have a directory that contains several related metadata files that depend on each other, such as movie file and a subtitle file.

When enabled, the newest lastModified() value of any contained files is considered the modified time of the entire directory.

This behavior can only be set on a directory, and it applies recursively to all contained files and directories.

Parameters
path File

group boolean

Throws
IOException

setCacheBehaviorTombstone

added in API level 26
void setCacheBehaviorTombstone (File path, 
                boolean tombstone)

Enable or disable special cache behavior that leaves deleted cache files intact as tombstones.

When enabled and a file contained in this directory is automatically deleted by the OS, the file will be truncated to have a length of 0 bytes instead of being fully deleted. This is useful if you need to distinguish between a file that was deleted versus one that never existed.

This behavior can only be set on a directory, and it applies recursively to all contained files and directories.

Note: this behavior is ignored completely if the user explicitly requests that all cached data be cleared.

Parameters
path File

tombstone boolean

Throws
IOException

unmountObb

added in API level 9
boolean unmountObb (String rawPath, 
                boolean force, 
                OnObbStateChangeListener listener)

Unmount an Opaque Binary Blob (OBB) file asynchronously. If the force flag is true, it will kill any application needed to unmount the given OBB (even the calling application).

The OnObbStateChangeListener registered with this call will receive the success or failure of this operation.

Note: you can only mount OBB files for which the OBB tag on the file matches a package ID that is owned by the calling program's UID. That is, shared UID applications can obtain access to any other application's OBB that shares its UID.

Parameters
rawPath String: path to the OBB file

force boolean: whether to kill any programs using this in order to unmount it

listener OnObbStateChangeListener: will receive the success or failure of the operation

Returns
boolean whether the unmount call was successfully queued or not

This site uses cookies to store your preferences for site-specific language and display options.

Get the latest Android developer news and tips that will help you find success on Google Play.

* Required Fields

Hooray!

Browse this site in ?

You requested a page in , but your language preference for this site is .

Would you like to change your language preference and browse this site in ? If you want to change your language preference later, use the language menu at the bottom of each page.

This class requires API level or higher

This doc is hidden because your selected API level for the documentation is . You can change the documentation API level with the selector above the left navigation.

For more information about specifying the API level your app requires, read Supporting Different Platform Versions.

Take a one-minute survey?
Help us improve Android tools and documentation.