Android编程调节屏幕亮度(背景灯)及保持背景灯常亮的方法

WindowManager.LayoutParams lp = getWindow().getAttributes();lp.screenBrightness = 0.1f;

public class BLightActivity extends Activity {/** Called when the activity is first created. */int Max_Brightness = 100;SeekBar bSeekBar = null;float fBrightness = 0.0f;WindowManager.LayoutParams lp = null;  @Override  public void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.main);    bSeekBar = (SeekBar) findViewById(R.id.bLightBar);    bSeekBar.setOnSeekBarChangeListener(seekListener);    bSeekBar.setMax(Max_Brightness);    lp = getWindow().getAttributes();//    lp.screenBrightness = 0.1f;  }OnSeekBarChangeListener seekListener = new OnSeekBarChangeListener() {public void onStopTrackingTouch(SeekBar seekBar) {// TODO Auto-generated method stub}public void onStartTrackingTouch(SeekBar seekBar) {// TODO Auto-generated method stub}public void onProgressChanged(SeekBar seekBar, int progress,boolean fromUser) {// TODO Auto-generated method stubfBrightness = (float)progress / (float)Max_Brightness;lp.screenBrightness = fBrightness;// 这句得加上，否则屏幕亮度不启作用getWindow().setAttributes(lp);System.out.println("FY_" + fBrightness);}};}

public class test extends Activity{  PowerManager powerManager = null;  WakeLock wakeLock = null;  @Override  protected void onCreate(Bundle savedInstanceState) {     super.onCreate(savedInstanceState);     this.setContentView(R.layout.main);     this.powerManager = (PowerManager)this.getSystemService(Context.POWER_SERVICE);     this.wakeLock = this.powerManager.newWakeLock(PowerManager.FULL_WAKE_LOCK, "My Lock");     this.wakeLock.acquire();   }  @Override  protected void onResume() {     super.onResume();     // 重新获取     this.wakeLock.acquire();   }   @Override   protected void onPause() {     super.onPause();     // 在Activity销毁的时候释放wakeLock     this.wakeLock.release();   } }