SeekBar调节手机屏幕亮度

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">

<SeekBar
android:id="@+id/seek_bar"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/showSeek"
android:textSize="20.0sp"
android:gravity="center"/>

</LinearLayout>

public class MainActivity extends AppCompatActivity {

private SeekBar seekBar;
private TextView showseek;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
init();

seekBar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
@Override
public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {

}

@Override
public void onStartTrackingTouch(SeekBar seekBar) {

}

@Override
public void onStopTrackingTouch(SeekBar seekBar) {
update((float)seekBar.getProgress()/10);
}
});
}

//实例化控件
private void init(){
seekBar= (SeekBar) findViewById(R.id.seek_bar);
showseek= (TextView) findViewById(R.id.showSeek);

//亮度是从0~1中的一个浮点数，由于getProess得到的是Int型，所以扩大10倍，赋值时除以10
seekBar.setMax(10);
}
private void update(float b){
//取得window属性保存在layoutParams中
WindowManager.LayoutParams layoutParams = getWindow().getAttributes();
layoutParams.screenBrightness = b;
getWindow().setAttributes(layoutParams);
//显示修改后的亮度
layoutParams = getWindow().getAttributes();
showseek.setText("当前亮度:"+String.valueOf(layoutParams.screenBrightness));
}
}