ListView的上拉加载，下拉更新，android上ListView上往往会要求加载一部分，上拉去加载下一页的内容，第二，listview不会自己去更新内容，这里实现了下拉会更新listview-ListView on Raja contained, drop-down update will often ask the loaded part, got me to load the next page of content on the ListView on the android, li