import android.support.animation.SpringAnimation; //导入依赖的package包/类
/**
 * 初始化开始动画
 */
private void initIconAnimation() {
    int screenH = DensityUtil.getScreenH(this);

    SpringForce springForce = new SpringForce()
            .setDampingRatio(SpringForce.DAMPING_RATIO_LOW_BOUNCY)
            .setStiffness(SpringForce.STIFFNESS_VERY_LOW)
            .setFinalPosition(0);
    SpringAnimation springAnimation = new SpringAnimation(mCivIcon, DynamicAnimation.TRANSLATION_Y)
            .setSpring(springForce)
            .setStartValue(screenH);

    springAnimation.addEndListener(new DynamicAnimation.OnAnimationEndListener() {
        @Override
        public void onAnimationEnd(DynamicAnimation animation, boolean canceled, float value, float velocity) {
            initTextAnimation();
        }
    });

    springAnimation.start();
}
 

import android.support.animation.SpringAnimation; //导入依赖的package包/类
void animateSettle(int targetOffset, float initialVelocity) {
    if (settling) return;
    if (sheetOffsetHelper.getTopAndBottomOffset() == targetOffset) {
      if (targetOffset >= dismissOffset) {
          dispatchDismissCallback();
      }
      return;
    }

    settling = true;
    final boolean dismissing = targetOffset == dismissOffset;
    // if we're dismissing, we don't want the view to decelerate as it reaches the bottom
    // so set a target position that actually overshoots a little
    final float finalPosition = dismissing ? dismissOffset * 1.1f : targetOffset;

    SpringAnimation anim = new SpringAnimation(
            sheetOffsetHelper, ViewOffsetHelper.OFFSET_Y, finalPosition)
            .setStartValue(sheetOffsetHelper.getTopAndBottomOffset())
            .setStartVelocity(initialVelocity)
            .setMinimumVisibleChange(DynamicAnimation.MIN_VISIBLE_CHANGE_PIXELS);
    anim.getSpring()
            .setStiffness(SETTLE_STIFFNESS)
            .setDampingRatio(SpringForce.DAMPING_RATIO_NO_BOUNCY);
    anim.addEndListener((animation, canceled, value, velocity) -> {
        dispatchPositionChangedCallback();
        if (dismissing) {
            dispatchDismissCallback();
        }
        settling = false;
    });
    if (callbacks != null && !callbacks.isEmpty()) {
        anim.addUpdateListener((animation, value, velocity) -> dispatchPositionChangedCallback());
    }
    anim.start();
}
 

import android.support.animation.SpringAnimation; //导入依赖的package包/类
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    mVelocityTracker = VelocityTracker.obtain();

    final ImageView droid = (ImageView) findViewById(R.id.droid);
    findViewById(android.R.id.content).setOnTouchListener(new View.OnTouchListener() {
        private final Rect mRect = new Rect();

        @Override
        public boolean onTouch(View v, MotionEvent event) {
            switch (event.getAction()) {
                case MotionEvent.ACTION_DOWN:
                    mDownX = event.getX();
                    mDownY = event.getY();
                    mVelocityTracker.addMovement(event);
                    return true;
                case MotionEvent.ACTION_MOVE:
                    float x = event.getX();
                    float y = event.getY();
                    droid.getHitRect(mRect);
                    if (mRect.contains((int) x, (int) y)) {
                        droid.setTranslationX(x - mDownX);
                        droid.setTranslationY(y - mDownY);
                        mVelocityTracker.addMovement(event);
                    }
                    return true;
                case MotionEvent.ACTION_UP:
                    // fall-thru
                case MotionEvent.ACTION_CANCEL:
                    mVelocityTracker.computeCurrentVelocity(1000);
                    if (droid.getTranslationX() != 0) {
                        SpringAnimation animX = new SpringAnimation(droid, SpringAnimation.TRANSLATION_X, 0);
                        animX.getSpring().setStiffness(getStiffness());
                        animX.getSpring().setDampingRatio(getDamping());
                        animX.setStartVelocity(mVelocityTracker.getXVelocity());
                        animX.start();
                    }
                    if (droid.getTranslationY() != 0) {
                        SpringAnimation animY = new SpringAnimation(droid, SpringAnimation.TRANSLATION_Y, 0);
                        animY.getSpring().setStiffness(getStiffness());
                        animY.getSpring().setDampingRatio(getDamping());
                        animY.setStartVelocity(mVelocityTracker.getYVelocity());
                        animY.start();
                    }
                    mVelocityTracker.clear();
                    return true;
            }
            return false;
        }
    });
}