Handler.postAtTime vs Handler.postDelayed

Question

android Handler类包含此方法:

public final boolean postAtTime (Runnable r, Object token, long uptimeMillis)

在给定时间发布Runnable.在token以后可以用于去除回调r从消息队列由于这种方法:

public final void removeCallbacks (Runnable r, Object token)

Handler类中不存在以下方法

public final boolean postDelayed (Runnable r, Object token, long delay)

有没有提供这种方法的充分理由？

Answer 1

查看源代码后,令牌对象最终传递给Message:

public final boolean postAtTime(Runnable r, Object token, long uptimeMillis)
308    {
309        return sendMessageAtTime(getPostMessage(r, token), uptimeMillis);
310    }

private static Message getPostMessage(Runnable r, Object token) {
608        Message m = Message.obtain();
609        m.obj = token;

和postDelay

 public final boolean postDelayed(Runnable r, long delayMillis)
330    {
331        return sendMessageDelayed(getPostMessage(r), delayMillis);
332    }

如果你想要的是

public final boolean postDelayed (Runnable r, Object token, long delay)

那么为什么不用

public final boolean postAtTime (Runnable r, Object token, long uptimeMillis)

因为它一样.

更新,忘了添加这个:

public final boolean sendMessageDelayed(Message msg, long delayMillis)
442    {
443        if (delayMillis < 0) {
444            delayMillis = 0;
445        }
446        return sendMessageAtTime(msg, SystemClock.uptimeMillis() + delayMillis);
447    }