Android 简单实现Activity界面变暗效果

效果图：

代码实现如下：

private void dimBackground(final float from, final float to) {
final Window window = getWindow();
ValueAnimator valueAnimator = ValueAnimator.ofFloat(from, to);
valueAnimator.setDuration(500);
valueAnimator.addUpdateListener(new AnimatorUpdateListener() {
@Override
public void onAnimationUpdate(ValueAnimator animation) {
WindowManager.LayoutParams params = window.getAttributes();
params.alpha = (Float) animation.getAnimatedValue();
window.setAttributes(params);
}
});

valueAnimator.start();
}

　变亮

dimBackground(0.5f,1.0f);

　变暗

dimBackground(1.0f,0.5f);