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PowerManager源码  

2011-06-06 13:20:02|  分类: 深入研究 |  标签: |举报 |字号 订阅

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http://hi-android.info/src/android/os/PowerManager.java.html
PowerManager类为对Android电源进行管理提供了接口。它位于android/os/PowerManager.java,但是它本身实现的东西很少,主要是调用了些更底层(C/C++)的函数.
关于如何通过PowerManager类来对Android电源进行管理请参考《PowerManager》,《Android电源管理简介
源文件:PowerManager.java  
package android.os;
import android.util.Log;
import com.android.internal.os.RuntimeInit;
public class PowerManager
{
    private static final String TAG = "PowerManager";
    private static final int WAKE_BIT_CPU_STRONG = 1;
    private static final int WAKE_BIT_CPU_WEAK = 2;
    private static final int WAKE_BIT_SCREEN_DIM = 4;
    private static final int WAKE_BIT_SCREEN_BRIGHT = 8;
    private static final int WAKE_BIT_KEYBOARD_BRIGHT = 16;
    private static final int WAKE_BIT_PROXIMITY_SCREEN_OFF = 32;
    private static final int LOCK_MASK = WAKE_BIT_CPU_STRONG
                                        | WAKE_BIT_CPU_WEAK
                                        | WAKE_BIT_SCREEN_DIM
                                        | WAKE_BIT_SCREEN_BRIGHT
                                        | WAKE_BIT_KEYBOARD_BRIGHT
                                        | WAKE_BIT_PROXIMITY_SCREEN_OFF;
    public static final int PARTIAL_WAKE_LOCK = WAKE_BIT_CPU_STRONG;
    public static final int FULL_WAKE_LOCK = WAKE_BIT_CPU_WEAK | WAKE_BIT_SCREEN_BRIGHT 
                                            | WAKE_BIT_KEYBOARD_BRIGHT;
    public static final int SCREEN_BRIGHT_WAKE_LOCK = WAKE_BIT_CPU_WEAK | WAKE_BIT_SCREEN_BRIGHT;
    public static final int SCREEN_DIM_WAKE_LOCK = WAKE_BIT_CPU_WEAK | WAKE_BIT_SCREEN_DIM;

    /**
     * Wake lock that turns the screen off when the proximity sensor activates.
     * Since not all devices have proximity sensors, use
     * {@link #getSupportedWakeLockFlags() getSupportedWakeLockFlags()} to determine if
     * this wake lock mode is supported.
     *
     * {@hide}
     */
    public static final int PROXIMITY_SCREEN_OFF_WAKE_LOCK = WAKE_BIT_PROXIMITY_SCREEN_OFF;
    /**
     * Flag for {@link WakeLock#release release(int)} to defer releasing a
     * {@link #WAKE_BIT_PROXIMITY_SCREEN_OFF} wakelock until the proximity sensor returns
     * a negative value.
     *
     * {@hide}
     */
    public static final int WAIT_FOR_PROXIMITY_NEGATIVE = 1;
    public static final int ACQUIRE_CAUSES_WAKEUP = 0x10000000;
    public static final int ON_AFTER_RELEASE = 0x20000000;   
    /**
     * Class lets you say that you need to have the device on.
     *
     * <p>Call release when you are done and don't need the lock anymore.
     */
    public class WakeLock
    {
        static final int RELEASE_WAKE_LOCK = 1;
        Runnable mReleaser = new Runnable() {
            public void run() {
                release();
            }
        };
        int mFlags;
        String mTag;
        IBinder mToken;
        int mCount = 0;
        boolean mRefCounted = true;
        boolean mHeld = false;
        WorkSource mWorkSource;
        WakeLock(int flags, String tag)
        {
            switch (flags & LOCK_MASK) {
            case PARTIAL_WAKE_LOCK:
            case SCREEN_DIM_WAKE_LOCK:
            case SCREEN_BRIGHT_WAKE_LOCK:
            case FULL_WAKE_LOCK:
            case PROXIMITY_SCREEN_OFF_WAKE_LOCK:
                break;
            default:
                throw new IllegalArgumentException();
            }

            mFlags = flags;
            mTag = tag;
            mToken = new Binder();
        }
        /**
         * Sets whether this WakeLock is ref counted.
         *
         * <p>Wake locks are reference counted by default.
         *
         * @param value true for ref counted, false for not ref counted.
         */
        public void setReferenceCounted(boolean value)
        {
            mRefCounted = value;
        }
        /**
         * Makes sure the device is on at the level you asked when you created
         * the wake lock.
         */
        public void acquire()
        {
            synchronized (mToken) {
                if (!mRefCounted || mCount++ == 0) {
                    try {
                        mService.acquireWakeLock(mFlags, mToken, mTag, mWorkSource);
                    } catch (RemoteException e) {
                    }
                    mHeld = true;
                }
            }
        }   
        /**
         * Makes sure the device is on at the level you asked when you created
         * the wake lock. The lock will be released after the given timeout.
         * 
         * @param timeout Release the lock after the give timeout in milliseconds.
         */
        public void acquire(long timeout) {
            acquire();
            mHandler.postDelayed(mReleaser, timeout);
        }
        /**
         * Release your claim to the CPU or screen being on.
         *
         * <p>
         * It may turn off shortly after you release it, or it may not if there
         * are other wake locks held.
         */
        public void release()
        {
            release(0);
        }
        /**
         * Release your claim to the CPU or screen being on.
         * @param flags Combination of flag values to modify the release behavior.
         *              Currently only {@link #WAIT_FOR_PROXIMITY_NEGATIVE} is supported.
         *
         * <p>
         * It may turn off shortly after you release it, or it may not if there
         * are other wake locks held.
         *
         * {@hide}
         */
        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);
                }
            }
        }
        public boolean isHeld()
        {
            synchronized (mToken) {
                return mHeld;
            }
        }
        public void setWorkSource(WorkSource ws) {
            synchronized (mToken) {
                if (ws != null && ws.size() == 0) {
                    ws = null;
                }
                boolean changed = true;
                if (ws == null) {
                    mWorkSource = null;
                } else if (mWorkSource == null) {
                    changed = mWorkSource != null;
                    mWorkSource = new WorkSource(ws);
                } else {
                    changed = mWorkSource.diff(ws);
                    if (changed) {
                        mWorkSource.set(ws);
                    }
                }
                if (changed && mHeld) {
                    try {
                        mService.updateWakeLockWorkSource(mToken, mWorkSource);
                    } catch (RemoteException e) {
                    }
                }
            }
        }
        public String toString() {
            synchronized (mToken) {
                return "WakeLock{"
                    + Integer.toHexString(System.identityHashCode(this))
                    + " held=" + mHeld + ", refCount=" + mCount + "}";
            }
        }
        @Override
        protected void finalize() throws Throwable
        {
            synchronized (mToken) {
                if (mHeld) {
                    Log.wtf(TAG, "WakeLock finalized while still held: " + mTag);
                    try {
                        mService.releaseWakeLock(mToken, 0);
                    } catch (RemoteException e) {
                    }
                }
            }
        }
    }
    public WakeLock newWakeLock(int flags, String tag)
    {
        if (tag == null) {
            throw new NullPointerException("tag is null in PowerManager.newWakeLock");
        }
        return new WakeLock(flags, tag);
    }
    public void userActivity(long when, boolean noChangeLights)
    {
        try {
            mService.userActivity(when, noChangeLights);
        } catch (RemoteException e) {
        }
    }
    public void goToSleep(long time) 
    {
        try {
            mService.goToSleep(time);
        } catch (RemoteException e) {
        }
    }
    /**
     * sets the brightness of the backlights (screen, keyboard, button).
     *
     * @param brightness value from 0 to 255
     *
     * {@hide}
     */
    public void setBacklightBrightness(int brightness)
    {
        try {
            mService.setBacklightBrightness(brightness);
        } catch (RemoteException e) {
        }
    }
   /**
     * Returns the set of flags for {@link #newWakeLock(int, String) newWakeLock()}
     * that are supported on the device.
     * For example, to test to see if the {@link #PROXIMITY_SCREEN_OFF_WAKE_LOCK}
     * is supported:
     *
     * {@samplecode
     * PowerManager pm = (PowerManager) getSystemService(Context.POWER_SERVICE);
     * int supportedFlags = pm.getSupportedWakeLockFlags();
     *  boolean proximitySupported = ((supportedFlags & PowerManager.PROXIMITY_SCREEN_OFF_WAKE_LOCK)
     *                                  == PowerManager.PROXIMITY_SCREEN_OFF_WAKE_LOCK);
     * }
     *
     * @return the set of supported WakeLock flags.
     *
     * {@hide}
     */
    public int getSupportedWakeLockFlags()
    {
        try {
            return mService.getSupportedWakeLockFlags();
        } catch (RemoteException e) {
            return 0;
        }
    }
   public boolean isScreenOn()
    {
        try {
            return mService.isScreenOn();
        } catch (RemoteException e) {
            return false;
        }
    }
    public void reboot(String reason)
    {
        try {
            mService.reboot(reason);
        } catch (RemoteException e) {
        }
    }
    private PowerManager()
    {
    }
    public PowerManager(IPowerManager service, Handler handler)
    {
        mService = service;
        mHandler = handler;
    } 
    IPowerManager mService;
    Handler mHandler;
}
注意* {@hide}表示该方法对外部开发用户是隐藏了,Android的对外API中并不提供该方法。
只有在Android系统的framework或应用程序中才能用。
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