怎么实现下拉刷新，上拉加载 原理

uexWindow.setBounce("1");

uexWindow.notifyBounceEvent("1", "1");

uexWindow.notifyBounceEvent("0", "1");

var s =
'{"imagePath":"","textColor":"#aaa","levelText":"","pullToReloadText":"上
拉加载更多内容...","releaseToReloadText":"释放加载更多内容...","loadingText":"加载中，请稍
等"}';

uexWindow.setBounceParams("1", s);

uexWindow.showBounceView("1", '#EAEAEA', '1');

var b =
'{"imagePath":"","textColor":"#aaa","levelText":"","pullToReloadText":"下
拉刷新更多内容...","releaseToReloadText":"释放加载更多内容...","loadingText":"刷新中，请稍
等"}';

uexWindow.setBounceParams("0", b);

uexWindow.showBounceView("0", '#EAEAEA', '1');