Android提供的系统服务之--PowerManager(电源服务)

——转载请注明出处:coder-pig

本节引言:

本节主要讲解的Android为我们提供的系统服务中的:PowerManager电源管理的一个API,

用于管理CPU运行,键盘或者屏幕亮起来;不过,除非是迫不得已吧,不然的话,否则应该尽量避免

使用这个类,并且使用完以后一定要及时释放!本节并不太深入的去讲解,因为这个设计到底层的

一些东西,以后需要用到再深入研究,到时再另外写一篇blog总结!所以本节介绍的主要是

一些基本的概念,PowerManager,wakelock锁的机制等等!

本节知识点图:

代码示例:

一个管理WakeLock以及Android设备电源管理的工具类:

import android.content.Context;
import android.content.SharedPreferences;
import android.os.PowerManager;
import android.preference.PreferenceManager;

public class ManageWakeLock {
    private static PowerManager.WakeLock mWakeLock = null;
    private static PowerManager.WakeLock mPartialWakeLock = null;
    private static final boolean PREFS_SCREENON_DEFAULT = true;
    private static final boolean PREFS_DIMSCREEN_DEFAULT = false;
    private static final String PREFS_TIMEOUT_DEFAULT = "30";

    public static synchronized void acquireFull(Context mContext) {
        if (mWakeLock != null) {
             return;
        }

        PowerManager mPm = (PowerManager) mContext.getSystemService(Context.POWER_SERVICE);
        SharedPreferences mPrefs = PreferenceManager.getDefaultSharedPreferences(mContext);

        int flags;

        flags = PowerManager.SCREEN_BRIGHT_WAKE_LOCK | PowerManager.ACQUIRE_CAUSES_WAKEUP;

        mWakeLock = mPm.newWakeLock(flags, “ManagerWakeLock”);
        mWakeLock.setReferenceCounted(false);
        mWakeLock.acquire();
    }

    public static synchronized void acquirePartical(Context mContext) {
        //Check if partial lock already exists
        if (mPartialWakeLock != null) {
            return;
        }

        PowerManager mPm = (PowerManager) mContext.getSystemService(Context.POWER_SERVICE);
        mPartialWakeLock = mPm.newWakeLock(PowerManager.SCREEN_BRIGHT_WAKE_LOCK
                                | PowerManager.ACQUIRE_CAUSES_WAKEUP, “ManagerWakeLock”);

        mPartialWakeLock.setReferenceCounted(false);
            mPartialWakeLock.acquire();
        }
    }
    public static synchronized void releaseFull() {
        if (mWakeLock != null) {
            mWakeLock.release();
            mWakeLock = null;
        }
    }

    public static synchronized void releasePartial() {
        if (mPartialWakeLock != null) {
             mPartialWakeLock.release();
             mPartialWakeLock = null;
        }
    }

    public static synchronized void releaseAll() {
        releaseFull();
        releasePartial();
    }
}

参考资料:

http://www.open-open.com/lib/view/open1343207436974.html

http://blog.csdn.net/xieqibao/article/details/6562256

http://blog.chinaunix.net/uid-27411029-id-4040727.html