Interpolator

动作特效： Interpolator 定义了动画的变化速度，可以实现匀速、正加速、负加速、无规则变加速等； Interpolator 是基类，封装了所有 Interpolator 的共同方法，它只有一个方法，即 getInterpolation (float input)，该方法 maps a point on the timeline to a multiplier to be applied to the transformations of an animation. AccelerateDecelerateInterpolator, AccelerateInterpolator, CycleInterpolator, DecelerateInterpolator, LinearInterpolator  AccelerateDecelerateInterpolator，延迟减速，在动作执行到中间的时候才执行该特效。An interpolator where the rate of change starts and ends slowly but accelerates through the middle.  AccelerateInterpolator, 会使慢慢以(float)的参数降低速度。An interpolator where the rate of change starts out slowly and and then accelerates. LinearInterpolator，平稳不变的，An interpolator where the rate of change is constant。 DecelerateInterpolator，在中间加速,两头慢，An interpolator where the rate of change starts out quickly and and then decelerates.  CycleInterpolator，曲线运动特效，要传递float型的参数。Repeats the animation for a specified number of cycles. The rate of change follows a sinusoidal pattern.