WifiManager.WifiLock
public
class
WifiManager.WifiLock
extends Object
java.lang.Object | |
↳ | android.net.wifi.WifiManager.WifiLock |
Allows an application to keep the Wi-Fi radio awake. Normally the Wi-Fi radio may turn off when the user has not used the device in a while. Acquiring a WifiLock will keep the radio on until the lock is released. Multiple applications may hold WifiLocks, and the radio will only be allowed to turn off when no WifiLocks are held in any application.
Before using a WifiLock, consider carefully if your application requires Wi-Fi access, or could function over a mobile network, if available. A program that needs to download large files should hold a WifiLock to ensure that the download will complete, but a program whose network usage is occasional or low-bandwidth should not hold a WifiLock to avoid adversely affecting battery life.
Note that WifiLocks cannot override the user-level "Wi-Fi Enabled" setting, nor Airplane Mode. They simply keep the radio from turning off when Wi-Fi is already on but the device is idle.
Any application using a WifiLock must request the android.permission.WAKE_LOCK
permission in an <uses-permission>
element of the application's manifest.
Summary
Public methods | |
---|---|
void
|
acquire()
Locks the Wi-Fi radio on until |
boolean
|
isHeld()
Checks whether this WifiLock is currently held. |
void
|
release()
Unlocks the Wi-Fi radio, allowing it to turn off when the device is idle. |
void
|
setReferenceCounted(boolean refCounted)
Controls whether this is a reference-counted or non-reference-counted WifiLock. |
void
|
setWorkSource(WorkSource ws)
|
String
|
toString()
Returns a string representation of the object. |
Protected methods | |
---|---|
void
|
finalize()
Called by the garbage collector on an object when garbage collection determines that there are no more references to the object. |
Inherited methods | |
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Public methods
acquire
public void acquire ()
Locks the Wi-Fi radio on until release()
is called.
If this WifiLock is reference-counted, each call to acquire
will increment the
reference count, and the radio will remain locked as long as the reference count is
above zero.
If this WifiLock is not reference-counted, the first call to acquire
will lock
the radio, but subsequent calls will be ignored. Only one call to release()
will be required, regardless of the number of times that acquire
is called.
isHeld
public boolean isHeld ()
Checks whether this WifiLock is currently held.
Returns | |
---|---|
boolean |
true if this WifiLock is held, false otherwise |
release
public void release ()
Unlocks the Wi-Fi radio, allowing it to turn off when the device is idle.
If this WifiLock is reference-counted, each call to release
will decrement the
reference count, and the radio will be unlocked only when the reference count reaches
zero. If the reference count goes below zero (that is, if release
is called
a greater number of times than acquire()
), an exception is thrown.
If this WifiLock is not reference-counted, the first call to release
(after
the radio was locked using acquire()
) will unlock the radio, and subsequent
calls will be ignored.
setReferenceCounted
public void setReferenceCounted (boolean refCounted)
Controls whether this is a reference-counted or non-reference-counted WifiLock.
Reference-counted WifiLocks keep track of the number of calls to acquire()
and
release()
, and only allow the radio to sleep when every call to acquire()
has been balanced with a call to release()
. Non-reference-counted WifiLocks
lock the radio whenever acquire()
is called and it is unlocked, and unlock the
radio whenever release()
is called and it is locked.
Parameters | |
---|---|
refCounted |
boolean : true if this WifiLock should keep a reference count |
setWorkSource
public void setWorkSource (WorkSource ws)
Parameters | |
---|---|
ws |
WorkSource |
toString
public String toString ()
Returns a string representation of the object.
Returns | |
---|---|
String |
a string representation of the object. |
Protected methods
finalize
protected void finalize ()
Called by the garbage collector on an object when garbage collection
determines that there are no more references to the object.
A subclass overrides the finalize
method to dispose of
system resources or to perform other cleanup.
The general contract of finalize
is that it is invoked
if and when the Java virtual
machine has determined that there is no longer any
means by which this object can be accessed by any thread that has
not yet died, except as a result of an action taken by the
finalization of some other object or class which is ready to be
finalized. The finalize
method may take any action, including
making this object available again to other threads; the usual purpose
of finalize
, however, is to perform cleanup actions before
the object is irrevocably discarded. For example, the finalize method
for an object that represents an input/output connection might perform
explicit I/O transactions to break the connection before the object is
permanently discarded.
The finalize
method of class Object
performs no
special action; it simply returns normally. Subclasses of
Object
may override this definition.
The Java programming language does not guarantee which thread will
invoke the finalize
method for any given object. It is
guaranteed, however, that the thread that invokes finalize will not
be holding any user-visible synchronization locks when finalize is
invoked. If an uncaught exception is thrown by the finalize method,
the exception is ignored and finalization of that object terminates.
After the finalize
method has been invoked for an object, no
further action is taken until the Java virtual machine has again
determined that there is no longer any means by which this object can
be accessed by any thread that has not yet died, including possible
actions by other objects or classes which are ready to be finalized,
at which point the object may be discarded.
The finalize
method is never invoked more than once by a Java
virtual machine for any given object.
Any exception thrown by the finalize
method causes
the finalization of this object to be halted, but is otherwise
ignored.
Throws | |
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Throwable |