java - Handler.postAtTime 与 Handler.postDelayed

Question

机器人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。由于此方法，token 稍后可用于从消息队列中删除对 r 的回调:

public final void removeCallbacks (Runnable r, Object token)

Handler 类中不存在的方法

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

是否有充分的理由不提供这种方法？

Answer 1

看了源码，token对象最终传给了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)

那为什么不直接使用

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

因为它是一样的。

更新，忘了加上这个:

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    }