HorizontalScrollView回弹效果

import android.annotation.SuppressLint;
import android.os.Build;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import android.view.ViewTreeObserver.OnGlobalLayoutListener;
import android.view.ViewTreeObserver.OnScrollChangedListener;
import android.widget.HorizontalScrollView;
import android.widget.ScrollView;

public class UITools {

    /**HorizontalScrollView添加阻尼效果
     * ScrollView效果不太好
     * 利用父元素的Padding给ScrollView添加弹性
     * @param scrollView
     * @param padding
     */
    public static void elasticPadding(final ScrollView scrollView, final int padding){
        View child = scrollView.getChildAt(0);
        //记录以前的padding
        final int oldpt = child.getPaddingTop();
        final int oldpb = child.getPaddingBottom();
        //设置新的padding
        child.setPadding(child.getPaddingLeft(), padding+oldpt, child.getPaddingRight(), padding+oldpb);

        //添加视图布局完成事件监听
        scrollView.getViewTreeObserver().addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
            private boolean inTouch = false; //手指是否按下状态

            @SuppressLint("NewApi")
            private void disableOverScroll(){
                scrollView.setOverScrollMode(ScrollView.OVER_SCROLL_NEVER);
            }

            /**  滚动到顶部 */
            private void scrollToTop(){
                scrollView.smoothScrollTo(scrollView.getScrollX(), padding-oldpt);
            }

            /** 滚动到底部 */
            private void scrollToBottom(){
                scrollView.smoothScrollTo(scrollView.getScrollX(), scrollView.getChildAt(0).getBottom()-scrollView.getMeasuredHeight()-padding+oldpb);
            }

            /** 检测scrollView结束以后,复原位置 */
            private final Runnable checkStopped = new Runnable() {
                @Override
                public void run() {
                    int y = scrollView.getScrollY();
                    int bottom = scrollView.getChildAt(0).getBottom()-y-scrollView.getMeasuredHeight();
                    if(y <= padding && !inTouch){
                        scrollToTop();
                    }else if(bottom<=padding && !inTouch){
                        scrollToBottom();
                    }
                }
            };

            @SuppressWarnings("deprecation")
            @Override
            public void onGlobalLayout() {
                //移除监听器
                scrollView.getViewTreeObserver().removeGlobalOnLayoutListener(this);
                //设置最小高度
                //scrollView.getChildAt(0).setMinimumHeight(scrollView.getMeasuredHeight());
                //取消overScroll效果
                if(Build.VERSION.SDK_INT > Build.VERSION_CODES.GINGERBREAD){
                    disableOverScroll();
                }

                scrollView.setOnTouchListener(new OnTouchListener() {
                    @Override
                    public boolean onTouch(View v, MotionEvent event) {
                        if(event.getAction() == MotionEvent.ACTION_DOWN || event.getAction() == MotionEvent.ACTION_POINTER_DOWN){
                            inTouch = true;
                        }else if(event.getAction() == MotionEvent.ACTION_UP || event.getAction() == MotionEvent.ACTION_CANCEL){
                            inTouch = false;
                            //手指弹起以后检测一次是否需要复原位置
                            scrollView.post(checkStopped);
                        }
                        return false;
                    }
                });

                scrollView.getViewTreeObserver().addOnScrollChangedListener(new OnScrollChangedListener() {
                    @Override
                    public void onScrollChanged() {
                        if(!inTouch && scrollView!=null && scrollView.getHandler()!=null){//如果持续滚动,移除checkStopped,停止滚动以后只执行一次检测任务
                            scrollView.getHandler().removeCallbacks(checkStopped);
                            scrollView.postDelayed(checkStopped, 100);
                        }
                    }
                });

                //第一次加载视图,复原位置
                scrollView.postDelayed(checkStopped, 300);
            }
        });
    }

    /**
     * 利用父元素的Padding给HorizontalScrollView添加弹性
     * @param scrollView
     * @param padding
     */
    public static void elasticPadding(final HorizontalScrollView scrollView, final int padding){
        Log.i("", "elasticPadding>>>>!!");
        View child = scrollView.getChildAt(0);

        //记录以前的padding
        final int oldpt = child.getPaddingTop();
        final int oldpb = child.getPaddingBottom();
        //设置新的padding
        child.setPadding(padding+oldpt, child.getPaddingTop(), padding+oldpb, child.getPaddingBottom());

        //添加视图布局完成事件监听
        scrollView.getViewTreeObserver().addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
            private boolean inTouch = false; //手指是否按下状态

            @SuppressLint("NewApi")
            private void disableOverScroll(){
                scrollView.setOverScrollMode(ScrollView.OVER_SCROLL_NEVER);
            }

            /**  滚动到左边 */
            private void scrollToLeft(){
                scrollView.smoothScrollTo(padding-oldpt, scrollView.getScrollY());
            }

            /** 滚动到底部 */
            private void scrollToRight(){
                scrollView.smoothScrollTo(scrollView.getChildAt(0).getRight()-scrollView.getMeasuredWidth()-padding+oldpb, scrollView.getScrollY());
            }

            /** 检测scrollView结束以后,复原位置 */
            private final Runnable checkStopped = new Runnable() {
                @Override
                public void run() {
                    int x = scrollView.getScrollX();
                    int bottom = scrollView.getChildAt(0).getRight()-x-scrollView.getMeasuredWidth();
                    if(x <= padding && !inTouch){
                        scrollToLeft();
                    }else if(bottom<=padding && !inTouch){
                        scrollToRight();
                    }
                }
            };

            @SuppressWarnings("deprecation")
            @Override
            public void onGlobalLayout() {
                //移除监听器
                scrollView.getViewTreeObserver().removeGlobalOnLayoutListener(this);

                //取消overScroll效果
                if(Build.VERSION.SDK_INT > Build.VERSION_CODES.GINGERBREAD){
                    disableOverScroll();
                }

                scrollView.setOnTouchListener(new OnTouchListener() {
                    @Override
                    public boolean onTouch(View v, MotionEvent event) {
                        if(event.getAction() == MotionEvent.ACTION_DOWN || event.getAction() == MotionEvent.ACTION_POINTER_DOWN){
                            inTouch = true;
                        }else if(event.getAction() == MotionEvent.ACTION_UP || event.getAction() == MotionEvent.ACTION_CANCEL){
                            inTouch = false;
                            //手指弹起以后检测一次是否需要复原位置
                            scrollView.post(checkStopped);
                        }
                        return false;
                    }
                });

                scrollView.getViewTreeObserver().addOnScrollChangedListener(new OnScrollChangedListener() {
                    @Override
                    public void onScrollChanged() {
                        //如果持续滚动,移除checkStopped,停止滚动以后只执行一次检测任务
                        if(!inTouch && scrollView!=null && scrollView.getHandler()!=null){
                            scrollView.getHandler().removeCallbacks(checkStopped);
                            scrollView.postDelayed(checkStopped, 100);
                        }
                    }
                });

                //第一次加载视图,复原位置
                scrollView.postDelayed(checkStopped, 300);
            }
        });
    }
}

用法：

UITools.elasticPadding((HorizontalScrollView) findViewById(R.id.hs), 300);

300表示回弹的最大距离。