弹性效果

public class BounceScrollView extends ScrollView {

	private View inner;// 孩子View

	private float y;// 点击时y坐标

	private Rect normal = new Rect();// 矩形(这里只是个形式，只是用于判断是否需要动画.)

	private boolean isCount = false;// 是否开始计算
	private float lastX = 0;
	private float lastY = 0;
	private float currentX = 0;
	private float currentY = 0;
	private float distanceX = 0;
	private float distanceY = 0;
	private boolean upDownSlide = false; // 判断上下滑动的flag

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

	/***
	 * 根据 XML 生成视图工作完成.该函数在生成视图的最后调用，在所有子视图添加完之后. 即使子类覆盖了 onFinishInflate
	 * 方法，也应该调用父类的方法，使该方法得以执行.
	 */
	@Override
	protected void onFinishInflate() {
		if (getChildCount() > 0) {
			inner = getChildAt(0);
		}
	}

	@Override
	public boolean dispatchTouchEvent(MotionEvent ev) {
		// TODO Auto-generated method stub
		currentX = ev.getX();
		currentY = ev.getY();
		switch (ev.getAction()) {
		case MotionEvent.ACTION_DOWN:

			break;
		case MotionEvent.ACTION_MOVE:
			distanceX = currentX - lastX;
			distanceY = currentY - lastY;
			if (Math.abs(distanceX) < Math.abs(distanceY) && distanceY < -12) {
				upDownSlide = true;
			}
			break;
		case MotionEvent.ACTION_UP:

			break;
		default:
			break;
		}
		lastX = currentX;
		lastY = currentY;
		if (upDownSlide && inner != null)
			commOnTouchEvent(ev);
		return super.dispatchTouchEvent(ev);
	}

	@Override
	public boolean onInterceptTouchEvent(MotionEvent ev) {
		// TODO Auto-generated method stub
		return super.onInterceptTouchEvent(ev);
	}

	/*** 
     * 触摸事件 
     *  
     * @param ev 
     */  
    public void commOnTouchEvent(MotionEvent ev) {  
        int action = ev.getAction();  
        switch (action) {  
        case MotionEvent.ACTION_DOWN:  
            break;  
        case MotionEvent.ACTION_UP:  
            // 手指松开.  
            if (isNeedAnimation()) {  
                animation();  
                isCount = false;  
            }  
            clear0();
            break;  
        case MotionEvent.ACTION_MOVE:  
            final float preY = y;// 按下时的y坐标  
            float nowY = ev.getY();// 时时y坐标  
            int deltaY = (int) (preY - nowY);// 滑动距离  
            if (!isCount) {  
                deltaY = 0; // 在这里要归0.  
            }  

            y = nowY;  
            // 当滚动到最上或者最下时就不会再滚动，这时移动布局  
            if (isNeedMove()) {  
                // 初始化头部矩形  
                if (normal.isEmpty()) {  
                    // 保存正常的布局位置  
                    normal.set(inner.getLeft(), inner.getTop(),  
                            inner.getRight(), inner.getBottom());  
                }  
                // 移动布局  
                inner.layout(inner.getLeft(), inner.getTop() - deltaY / 2,  
                        inner.getRight(), inner.getBottom() - deltaY / 2);  
            }  
            isCount = true;  
            break;  

        default:  
            break;  
        }  
    }

	/***
	 * 回缩动画
	 */
	public void animation() {
		// 开启移动动画
		TranslateAnimation ta = new TranslateAnimation(0, 0, inner.getTop(), normal.top);
		ta.setDuration(200);
		inner.startAnimation(ta);
		// 设置回到正常的布局位置
		inner.layout(normal.left, normal.top, normal.right, normal.bottom);

		normal.setEmpty();

	}

	// 是否需要开启动画
	public boolean isNeedAnimation() {
		return !normal.isEmpty();
	}

	/***
	 * 是否需要移动布局 inner.getMeasuredHeight():获取的是控件的总高度
	 * 
	 * getHeight()：获取的是屏幕的高度
	 * 
	 * @return
	 */
	public boolean isNeedMove() {
		int offset = inner.getMeasuredHeight() - getHeight();
		int scrollY = getScrollY();
		// 0是顶部，后面那个是底部
		if (scrollY == 0 || scrollY == offset) {
			return true;
		}
		return false;
	}

	private void clear0(){
        lastX = 0;
        lastY = 0;
        distanceX = 0;
        distanceY = 0;
        upDownSlide = false;
    }
}

    <com.example.test.BounceScrollView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@android:color/white" >

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:orientation="vertical" >

            <Button
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="Button" />

            <Button
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="Button" />

            <Button
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="Button" />

            <Button
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="Button" />

            <Button
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="Button" />

            <Button
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="Button" />

            <Button
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="Button" />

            <Button
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="Button" />

            <Button
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="Button" />

            <Button
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="Button" />

            <Button
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="Button" />

            <Button
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="Button" />

            <Button
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="Button" />

            <Button
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="Button" />

            <Button
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="Button" />

            <Button
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="Button" />

            <Button
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="Button" />

            <Button
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="Button" />

            <Button
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="Button" />

            <Button
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="Button" />

            <Button
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="Button" />

            <Button
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="Button" />

            <Button
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="Button" />

            <Button
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="Button" />

            <Button
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="Button" />

            <Button
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="Button" />

            <Button
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="Button" />

            <Button
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="Button" />

            <Button
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="Button" />

            <Button
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="Button" />

            <Button
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="Button" />

            <Button
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="Button" />

            <Button
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="Button" />

            <Button
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="Button" />

            <Button
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="Button" />

            <Button
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="Button" />

            <Button
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="Button" />

            <Button
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="Button" />
        </LinearLayout>
    </com.example.test.BounceScrollView>