android animator 动画
animator 动画动画的作用是让UI有动感， 看上去时尚。
Android中动画分两种方式：
一种方式是补间动画Tween Animation，就是说你定义一个开始和结束，中间的部分由程序运算得到。另一种叫逐帧动画Frame Animation，就是说一帧一帧的连起来播放就变成了动画。
动画可以实现的效果： 1. 移动(Translation) 2. 透明度(alpha) 3. 旋转（rotate） 4. 缩放 (scale)
现在分别用例子来讲解：以下的实现都是用代码实现的(ObjectAnimator)
1. 移动(Translation) 主要代码
AnimatorSet set = new AnimatorSet() ; ObjectAnimator anim = ObjectAnimator .ofFloat(phone, "scaleX", 1f);anim.setDuration(1000);ObjectAnimator anim2 = ObjectAnimator .ofFloat(phone, "scaleX", 0.5f);anim2.setDuration(1000);ObjectAnimator anim3 = ObjectAnimator .ofFloat(phone, "scaleY", 1f);anim3.setDuration(1000);ObjectAnimator anim4 = ObjectAnimator .ofFloat(phone, "scaleY", 0.5f);anim4.setDuration(1000);ObjectAnimator anim5 = ObjectAnimator .ofFloat(phone, "scaleX", 0.5f);anim5.setDuration(1000);ObjectAnimator anim6 = ObjectAnimator .ofFloat(phone, "scaleX", 1f);anim6.setDuration(1000);ObjectAnimator anim7 = ObjectAnimator .ofFloat(phone, "scaleY",0.5f);anim7.setDuration(1000);ObjectAnimator anim8 = ObjectAnimator .ofFloat(phone, "scaleY", 1f);anim8.setDuration(1000);AnimatorSet set3 = new AnimatorSet() ; set3.play(anim5).before(anim6);AnimatorSet set2 = new AnimatorSet() ; set2.play(anim2).before(set3) ; AnimatorSet set4 = new AnimatorSet() ; set4.play(anim7).before(anim8) ;AnimatorSet set5 = new AnimatorSet() ; set5.play(anim4).before(set4);set.play(anim).before(set2);set.play(anim3).before(set5) ;set.start();
