retryWhen 解决多次调用retry(),在subscribe之前dispose掉之前的 将重连放到扩展函数中[作者空间]
相同点 区别 distinctUntilChanged只确保相邻元素不重复出现 distinct会过滤掉之前已发射...[作者空间]
Operators that transform items that are emitted by an Obs...[作者空间]
Defer — do not create the Observable until the observer s...[作者空间]