android屏幕常亮保持
相关的变量:
PowerManager powerManager = null;
WakeLock wakeLock = null;
初始化:
powerManager = (PowerManager) this
.getSystemService(Service.POWER_SERVICE);
wakeLock = this.powerManager.newWakeLock(
PowerManager.SCREEN_DIM_WAKE_LOCK, "My Lock");
开启屏幕常亮:
wakeLock.setReferenceCounted(false);
wakeLock.acquire();
关闭你的程序设置的屏幕常亮:
wakeLock.release();
注意的地方:我在实际的调试过程中,没有设置wakeLock.setReferenceCounted(false);这个,报错为:java.lang.RuntimeException: WakeLock under-locked
阅读源码:
acquire()函数如下:
public void acquire()
{
synchronized (mToken) {
if (!mRefCounted || mCount++ == 0) {
try {
mService.acquireWakeLock(mFlags, mToken, mTag);
} catch (RemoteException e) {
}
mHeld = true;
}
}
}
release()函数如下:
public void release()
{
release(0);
}
public void release(int flags)
{
synchronized (mToken) {
if (!mRefCounted || --mCount == 0) {
try {
mService.releaseWakeLock(mToken, flags);
} catch (RemoteException e) {
}
mHeld = false;
}
if (mCount < 0) {
throw new RuntimeException("WakeLock under-locked " + mTag);
}
}
}
报错就抱在release(int flags)中,mCount为负数了,抛除了异常
我们再看下:setReferenceCounted(boolean flags);
public void setReferenceCounted(boolean value)
{
mRefCounted = value;
}
这个函数的作用是是不是需要计算锁的数量,设置为false时,在release()的时候,不管你acquire()了多少回,可以releaseWakeLock掉
网上看到很多 acquire()后直接就调用release(),误导大家
这个是我自己的一些看法,欢迎探讨