旋转动画实现

ImageView loading = (ImageView) findViewById(R.id.iv_pre_loading);

 private void showRotate() {
        Animation mRotateAnimation = new RotateAnimation(0.0f, 720.0f, Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF, 0.5f);
        mRotateAnimation.setFillAfter(true);
        mRotateAnimation.setInterpolator(new LinearInterpolator());
        mRotateAnimation.setDuration(1200);
        mRotateAnimation.setRepeatCount(Animation.INFINITE);
        mRotateAnimation.setRepeatMode(Animation.RESTART);
        loading.setVisibility(View.VISIBLE);
        //设置为半透明
        loading.setAlpha(0.5f);
        loading.setAnimation(mRotateAnimation);
    }

    private void stopRotate() {
        loading.setAnimation(null);
        loading.setVisibility(View.GONE);
    }