import android.content.Context;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.view.animation.TranslateAnimation;
import android.widget.ScrollView;

public class ReboundScrollView extends ScrollView {

  private static final float MOVE_DELAY = 0.3f;//当拉出屏幕时的拖拽系数
  private static final int ANIM_TIME = 300;//回弹耗时
  private static final int FLING = 2;//fling 系数

  private View childView;
  private boolean havaMoved;

  private Rect originalRect = new Rect();

  private float startY;

  @Override
  protected void onFinishInflate() {
    super.onFinishInflate();
    if (getChildCount() > 0) {
      childView = getChildAt(0);
    }
  }

  @Override
  public void fling(int velocityY) {
    super.fling(velocityY / 2);
  }

  @Override
  protected void onLayout(boolean changed, int l, int t, int r, int b) {
    super.onLayout(changed, l, t, r, b);

    if (childView == null)
      return;

    originalRect.set(childView.getLeft(), childView.getTop(),
        childView.getRight(), childView.getBottom());
  }


  public ReboundScrollView(Context context, AttributeSet attrs,
               int defStyle) {
    super(context, attrs, defStyle);
  }

  public ReboundScrollView(Context context, AttributeSet attrs) {
    super(context, attrs);
  }

  public ReboundScrollView(Context context) {
    super(context);
  }


  /**
   * 在触摸事件中, 处理上拉和下拉的逻辑
   */
  @Override
  public boolean dispatchTouchEvent(MotionEvent ev) {

    if (childView == null) {
      return super.dispatchTouchEvent(ev);
    }

    int action = ev.getAction();

    switch (action) {
      case MotionEvent.ACTION_DOWN:
        startY = ev.getY();
        break;

      case MotionEvent.ACTION_UP:
      case MotionEvent.ACTION_CANCEL:
        if (!havaMoved)
          break;

        TranslateAnimation anim = new TranslateAnimation(0, 0,
            childView.getTop(), originalRect.top);
        anim.setDuration(ANIM_TIME);

        childView.startAnimation(anim);
        // 将标志位设回false
        havaMoved = false;
        resetViewLayout();

        break;
      case MotionEvent.ACTION_MOVE:

        float nowY = ev.getY();
        int deltaY = (int) (nowY - startY);
        int offset = (int) (deltaY * MOVE_DELAY);
        childView.layout(originalRect.left, originalRect.top + offset,
            originalRect.right, originalRect.bottom + offset);

        havaMoved = true;

        break;
      default:
        break;
    }

    return super.dispatchTouchEvent(ev);
  }

  public void resetViewLayout() {
    childView.layout(originalRect.left, originalRect.top,
        originalRect.right, originalRect.bottom);
  }

}

 float nowY = ev.getY();
        int deltaY = (int) (nowY - startY);
        int offset = (int) (deltaY * MOVE_DELAY);
        childView.layout(originalRect.left, originalRect.top + offset,
            originalRect.right, originalRect.bottom + offset);

        havaMoved = true;

 if (!havaMoved)
          break;

        TranslateAnimation anim = new TranslateAnimation(0, 0,
            childView.getTop(), originalRect.top);
        anim.setDuration(ANIM_TIME);

        childView.startAnimation(anim);
        // 将标志位设回false
        havaMoved = false;
        resetViewLayout();
...
...
 public void resetViewLayout() {
    childView.layout(originalRect.left, originalRect.top,
        originalRect.right, originalRect.bottom);
  }