獲得Message對(duì)象, 盡量使用Handler的obtainMessage(int what), 而不要直接使用new Message()
Message msg = new Message();
msg.what = 1;
msg.arg1 = x;
msg.arg2 = y;
VS:
Handler handler;
Message msg = handler.obtainMessage(1);
Handler.java 源碼:
public final Message obtainMessage(int what, Object obj)
{
return Message.obtain(this, what, obj);
}
Message.java 源碼:
public static Message obtain(Handler h, int what, Object obj) {
Message m = obtain();
m.target = h;
m.what = what;
m.obj = obj;
return m;
}
/**
* Return a new Message instance from the global pool. Allows us to
* avoid allocating new objects in many cases.
*/
public static Message obtain() {
synchronized (sPoolSync) {
if (sPool != null) {
Message m = sPool;
sPool = m.next;
m.next = null;
m.flags = 0; // clear in-use flag
sPoolSize--;
return m;
}
}
return new Message();
}
可以看到這樣一段注釋， "從一個(gè)message pool里返回一個(gè)message對(duì)象紫新，避免創(chuàng)建新的對(duì)象."
所以為了性能最優(yōu)旬牲， 應(yīng)該盡量避免直接去new Message().
