StorageVolume
public
final
class
StorageVolume
extends Object
implements
Parcelable
java.lang.Object | |
↳ | android.os.storage.StorageVolume |
Information about a shared/external storage volume for a specific user.
A device always has one (and one only) primary storage volume, but it could have extra volumes, like SD cards and USB drives. This object represents the logical view of a storage volume for a specific user: different users might have different views for the same physical volume (for example, if the volume is a built-in emulated storage).
The storage volume is not necessarily mounted, applications should use getState()
to
verify its state.
Applications willing to read or write to this storage volume needs to get a permission from the user first, which can be achieved in the following ways:
- To get access to standard directories (like the
Environment.DIRECTORY_PICTURES
), they can use thecreateAccessIntent(java.lang.String)
. This is the recommend way, since it provides a simpler API and narrows the access to the given directory (and its descendants). - To get access to any directory (and its descendants), they can use the Storage Access
Framework APIs (such as
Intent.ACTION_OPEN_DOCUMENT
andIntent.ACTION_OPEN_DOCUMENT_TREE
, although these APIs do not guarantee the user will select this specific volume. - To get read and write access to the primary storage volume, applications can declare the
Manifest.permission.READ_EXTERNAL_STORAGE
andManifest.permission.WRITE_EXTERNAL_STORAGE
permissions respectively, with the latter including the former. This approach is discouraged, since users may be hesitant to grant broad access to all files contained on a storage device.
It can be obtained through StorageManager.getStorageVolumes()
and
StorageManager.getPrimaryStorageVolume()
and also as an extra in some broadcasts
(see EXTRA_STORAGE_VOLUME
).
See Environment.getExternalStorageDirectory()
for more info about shared/external
storage semantics.
Summary
Constants | |
---|---|
String |
EXTRA_STORAGE_VOLUME
Name of the |
Inherited constants |
---|
Fields | |
---|---|
public
static
final
Creator<StorageVolume> |
CREATOR
|
Public methods | |
---|---|
Intent
|
createAccessIntent(String directoryName)
This method was deprecated
in API level 29.
Callers should migrate to using |
Intent
|
createOpenDocumentTreeIntent()
Builds an |
int
|
describeContents()
Describe the kinds of special objects contained in this Parcelable instance's marshaled representation. |
boolean
|
equals(Object obj)
Indicates whether some other object is "equal to" this one. |
String
|
getDescription(Context context)
Returns a user-visible description of the volume. |
File
|
getDirectory()
Returns the directory where this volume is currently mounted. |
String
|
getMediaStoreVolumeName()
Return the volume name that can be used to interact with this storage
device through |
UserHandle
|
getOwner()
Returns the user that owns this volume |
String
|
getState()
Returns the current state of the volume. |
UUID
|
getStorageUuid()
Gets the converted volume UUID. |
String
|
getUuid()
Gets the volume UUID, if any. |
int
|
hashCode()
Returns a hash code value for the object. |
boolean
|
isEmulated()
Returns true if the volume is emulated. |
boolean
|
isPrimary()
Returns true if the volume is the primary shared/external storage, which is the volume
backed by |
boolean
|
isRemovable()
Returns true if the volume is removable. |
String
|
toString()
Returns a string representation of the object. |
void
|
writeToParcel(Parcel parcel, int flags)
Flatten this object in to a Parcel. |
Inherited methods | |
---|---|
Constants
EXTRA_STORAGE_VOLUME
public static final String EXTRA_STORAGE_VOLUME
Name of the Parcelable
extra in the Intent.ACTION_MEDIA_REMOVED
,
Intent.ACTION_MEDIA_UNMOUNTED
, Intent.ACTION_MEDIA_CHECKING
,
Intent.ACTION_MEDIA_NOFS
, Intent.ACTION_MEDIA_MOUNTED
,
Intent.ACTION_MEDIA_SHARED
, Intent.ACTION_MEDIA_BAD_REMOVAL
,
Intent.ACTION_MEDIA_UNMOUNTABLE
, and Intent.ACTION_MEDIA_EJECT
broadcast that
contains a StorageVolume
.
Constant Value: "android.os.storage.extra.STORAGE_VOLUME"
Fields
Public methods
createAccessIntent
public Intent createAccessIntent (String directoryName)
This method was deprecated
in API level 29.
Callers should migrate to using Intent.ACTION_OPEN_DOCUMENT_TREE
instead.
Launching this Intent
on devices running
Build.VERSION_CODES.Q
or higher, will immediately finish
with a result code of Activity.RESULT_CANCELED
.
Builds an intent to give access to a standard storage directory or entire volume after obtaining the user's approval.
When invoked, the system will ask the user to grant access to the requested directory (and
its descendants). The result of the request will be returned to the activity through the
onActivityResult
method.
To gain access to descendants (child, grandchild, etc) documents, use
DocumentsContract.buildDocumentUriUsingTree(Uri, String)
, or
DocumentsContract.buildChildDocumentsUriUsingTree(Uri, String)
with the returned URI.
If your application only needs to store internal data, consider using
Context.getExternalFilesDirs
,
Context.getExternalCacheDirs()
, or Context.getExternalMediaDirs()
, which
require no permissions to read or write.
Access to the entire volume is only available for non-primary volumes (for the primary
volume, apps can use the Manifest.permission.READ_EXTERNAL_STORAGE
and
Manifest.permission.WRITE_EXTERNAL_STORAGE
permissions) and should be used
with caution, since users are more likely to deny access when asked for entire volume access
rather than specific directories.
Parameters | |
---|---|
directoryName |
String : must be one of Environment.DIRECTORY_MUSIC ,
Environment.DIRECTORY_PODCASTS , Environment.DIRECTORY_RINGTONES ,
Environment.DIRECTORY_ALARMS , Environment.DIRECTORY_NOTIFICATIONS ,
Environment.DIRECTORY_PICTURES , Environment.DIRECTORY_MOVIES ,
Environment.DIRECTORY_DOWNLOADS , Environment.DIRECTORY_DCIM , or
Environment.DIRECTORY_DOCUMENTS , or null to request access to the
entire volume. |
Returns | |
---|---|
Intent |
intent to request access, or null if the requested directory is invalid for
that volume. |
See also:
createOpenDocumentTreeIntent
public Intent createOpenDocumentTreeIntent ()
Builds an Intent.ACTION_OPEN_DOCUMENT_TREE
to allow the user to grant access to any
directory subtree (or entire volume) from the DocumentsProvider
s
available on the device. The initial location of the document navigation will be the root of
this StorageVolume
.
Note that the returned Intent
simply suggests that the user picks this StorageVolume
by default, but the user may select a different location. Callers must respect
the user's chosen location, even if it is different from the originally requested location.
Returns | |
---|---|
Intent |
intent to Intent.ACTION_OPEN_DOCUMENT_TREE initially showing the contents
of this StorageVolume
This value cannot be null . |
See also:
describeContents
public int describeContents ()
Describe the kinds of special objects contained in this Parcelable
instance's marshaled representation. For example, if the object will
include a file descriptor in the output of writeToParcel(android.os.Parcel, int)
,
the return value of this method must include the
CONTENTS_FILE_DESCRIPTOR
bit.
Returns | |
---|---|
int |
a bitmask indicating the set of special object types marshaled
by this Parcelable object instance.
Value is either 0 or CONTENTS_FILE_DESCRIPTOR |
equals
public boolean equals (Object obj)
Indicates whether some other object is "equal to" this one.
The equals
method implements an equivalence relation
on non-null object references:
- It is reflexive: for any non-null reference value
x
,x.equals(x)
should returntrue
. - It is symmetric: for any non-null reference values
x
andy
,x.equals(y)
should returntrue
if and only ify.equals(x)
returnstrue
. - It is transitive: for any non-null reference values
x
,y
, andz
, ifx.equals(y)
returnstrue
andy.equals(z)
returnstrue
, thenx.equals(z)
should returntrue
. - It is consistent: for any non-null reference values
x
andy
, multiple invocations ofx.equals(y)
consistently returntrue
or consistently returnfalse
, provided no information used inequals
comparisons on the objects is modified. - For any non-null reference value
x
,x.equals(null)
should returnfalse
.
An equivalence relation partitions the elements it operates on into equivalence classes; all the members of an equivalence class are equal to each other. Members of an equivalence class are substitutable for each other, at least for some purposes.
Parameters | |
---|---|
obj |
Object : This value may be null . |
Returns | |
---|---|
boolean |
true if this object is the same as the obj
argument; false otherwise. |
getDescription
public String getDescription (Context context)
Returns a user-visible description of the volume.
Parameters | |
---|---|
context |
Context |
Returns | |
---|---|
String |
the volume description |
getDirectory
public File getDirectory ()
Returns the directory where this volume is currently mounted.
Direct filesystem access via this path has significant emulation
overhead, and apps are instead strongly encouraged to interact with media
on storage volumes via the MediaStore
APIs.
This directory does not give apps any additional access beyond what they
already have via MediaStore
.
Returns | |
---|---|
File |
directory where this volume is mounted, or null if the
volume is not currently mounted. |
getMediaStoreVolumeName
public String getMediaStoreVolumeName ()
Return the volume name that can be used to interact with this storage
device through MediaStore
.
Returns | |
---|---|
String |
opaque volume name, or null if this volume is not indexed
by MediaStore . |
getOwner
public UserHandle getOwner ()
Returns the user that owns this volume
Returns | |
---|---|
UserHandle |
This value cannot be null . |
getState
public String getState ()
Returns the current state of the volume.
getStorageUuid
public UUID getStorageUuid ()
Gets the converted volume UUID. If a valid UUID is returned, it is compatible with other
APIs that make use of UUID
like StorageManager.allocateBytes
and
ApplicationInfo.storageUuid
Returns | |
---|---|
UUID |
the UUID for the volume or null for "portable" storage devices which haven't
been adopted. |
See also:
getUuid
public String getUuid ()
Gets the volume UUID, if any.
Returns | |
---|---|
String |
This value may be null . |
hashCode
public int hashCode ()
Returns a hash code value for the object. This method is
supported for the benefit of hash tables such as those provided by
HashMap
.
The general contract of hashCode
is:
- Whenever it is invoked on the same object more than once during
an execution of a Java application, the
hashCode
method must consistently return the same integer, provided no information used inequals
comparisons on the object is modified. This integer need not remain consistent from one execution of an application to another execution of the same application. - If two objects are equal according to the
equals
method, then calling thehashCode
method on each of the two objects must produce the same integer result. - It is not required that if two objects are unequal
according to the
equals
method, then calling thehashCode
method on each of the two objects must produce distinct integer results. However, the programmer should be aware that producing distinct integer results for unequal objects may improve the performance of hash tables.
Returns | |
---|---|
int |
a hash code value for this object. |
isEmulated
public boolean isEmulated ()
Returns true if the volume is emulated.
Returns | |
---|---|
boolean |
is emulated |
isPrimary
public boolean isPrimary ()
Returns true if the volume is the primary shared/external storage, which is the volume
backed by Environment.getExternalStorageDirectory()
.
Returns | |
---|---|
boolean |
isRemovable
public boolean isRemovable ()
Returns true if the volume is removable.
Returns | |
---|---|
boolean |
is removable |
toString
public String toString ()
Returns a string representation of the object.
Returns | |
---|---|
String |
a string representation of the object. |
writeToParcel
public void writeToParcel (Parcel parcel, int flags)
Flatten this object in to a Parcel.
Parameters | |
---|---|
parcel |
Parcel : The Parcel in which the object should be written.
This value cannot be null . |
flags |
int : Additional flags about how the object should be written.
May be 0 or Parcelable.PARCELABLE_WRITE_RETURN_VALUE .
Value is either 0 or a combination of Parcelable.PARCELABLE_WRITE_RETURN_VALUE , and android.os.Parcelable.PARCELABLE_ELIDE_DUPLICATES |