Handler low.message.

Note that there are two classes: Message and Messager. In fact, the function is similar.

Each Messager has a handler.

MSGR. Send (MSG );

1. Messenger MSGR = new messenger (mhandler );

2. Public Messenger (handler target ){
Mtarget = target. getimessenger ();
}

3. Final imessenger getimessenger (){
Synchronized (mqueue ){
If (mmessenger! = NULL ){
Return mmessenger;
}
Mmessenger = new messengerimpl ();
Return mmessenger;
}
}

4. Private final class messengerimpl extends imessenger. Stub {
Public void send (Message MSG ){
Handler. This. sendmessage (MSG );
}
}

5. Public final Boolean sendmessage (Message MSG)
{
Return sendmessagedelayed (MSG, 0 );
}

6. Public Boolean sendmessageattime (Message MSG, long uptimemillis ){
Messagequeue queue = mqueue;
If (queue = NULL ){
Runtimeexception E = new runtimeexception (
This + "sendmessageattime () called with no mqueue ");
Log. W ("logoff", E. getmessage (), e );
Return false;
}
Return enqueuemessage (queue, MSG, uptimemillis );
}

Operations 3-6 are in handler. java.

Message MSG = uihandler. obtainmessage (100, backstr );

MSG. sendtotarget ();

1 public final message obtainmessage (INT what, object OBJ)
{
Return message. Obtain (this, what, OBJ );
}

2 public static message obtain (handler H, int what, object OBJ ){
Message M = obtain ();
M.tar get = h;
M. What = what;
M. OBJ = OBJ;

Return m;
}
3 Public void sendtotarget (){
Target. sendmessage (this); // send yourself
}

Post usage
Looperhandler. Post (New runnable (){

@ Override
Public void run (){
Log. I ("Glenn:", "From post! ");
}

});

1 public final Boolean post (runnable R)
{
Return sendmessagedelayed (getpostmessage (R), 0 );
}

2 Private Static message getpostmessage (runnable R ){
Message M = message. Obtain ();
M. Callback = R;
Return m;
}

3 Public void dispatchmessage (Message MSG ){
If (msg. callback! = NULL ){
Handlecallback (MSG); // call post
} Else {
If (mcallback! = NULL ){
If (mcallback. handlemessage (MSG )){
Return;
}
}
Handlemessage (MSG );
}
}
4.
Private Static void handlecallback (message ){
Message. Callback. Run ();
}