Android 屏幕常亮N秒後自動暗屏

 Android，在用戶不操作的情況下，定時使屏幕變暗，體驗會很好。直接看代碼吧。

    // 最大的屏幕亮度   
    private float maxLight;
	// 當前的亮度  
    private float currentLight;
	// 用來控制屏幕亮度  
    private Handler lightHandler;
    // 60秒時間不點擊屏幕，屏幕變暗 
    private long delayTime = 60 * 1000L; 
	
	
	protected void onCreate() {
		
		// 保持屏幕常亮
		getWindow().setFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON,
				WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
				
		// 屏幕亮度控制
		lightHandler = new Handler(Looper.getMainLooper());  
        maxLight = getLightness(); 
		
		
	}
	
	@Override
    public boolean dispatchTouchEvent(MotionEvent ev) {
		if (currentLight == 1) {
			startSleepTask();
			return false;
		}
       	startSleepTask();  
        return super.dispatchTouchEvent(ev);
    }
	
	/** 
     * 獲取亮度 
     */  
    private float getLightness() {
        WindowManager.LayoutParams localLayoutParams = this.getWindow().getAttributes();  
        return localLayoutParams.screenBrightness;  
    }
    
    /** 
     * 設置亮度  
     */  
    private void setLightness(int light) {  
        currentLight = light;  
        WindowManager.LayoutParams localLayoutParams = this.getWindow().getAttributes();
        localLayoutParams.screenBrightness = (light / 255.0F);
        this.getWindow().setAttributes(localLayoutParams);
    }
	
	/** 
     * 開啓休眠任務 
     */  
    private void startSleepTask() {  
	    setLightness((int) maxLight);  
	    stopSleepTask();
	    lightHandler.postDelayed(sleepWindowTask, delayTime);
    }  
  
    /** 
     * 結束休眠任務 
     */  
    private void stopSleepTask() {  
    	lightHandler.removeCallbacks(sleepWindowTask);  
    }  
  
    /** 
     * 休眠任務 
     */ 
	Runnable sleepWindowTask = new Runnable() {  
        @Override  
        public void run() {
        	setLightness(1);  
        }  
    };