Android Note (33) communication between Android threads (v) thread, Handle, Looper, and MessageQueue

ThreadLocal

Before looking down, you need to know about Java's threadlocal class, you can refer to the blog:

Decryption threadlocal

Looper, Handler and MessageQueue

Let's analyze the previous code and see what the relationship between Handle, Looper, and MessageQueue is in the handler mechanism.

 Packagecn.lixyz.handlertest;Importandroid.app.Activity;ImportAndroid.os.Bundle;ImportAndroid.os.Handler;ImportAndroid.os.Looper;ImportAndroid.os.Message;ImportAndroid.util.Log;ImportAndroid.view.View;ImportAndroid.widget.Button; Public classMainactivityextendsActivity {Privatebutton button; PrivateHandler Handler; @Overrideprotected voidonCreate (Bundle savedinstancestate) {Super. OnCreate (savedinstancestate);        Setcontentview (R.layout.activity_main); Button=(Button) Findviewbyid (R.id.button); Button.setonclicklistener (NewView.onclicklistener () {@Override Public voidOnClick (View v) {Message msg=Handler.obtainmessage (); Msg.what= 100;                Handler.sendmessage (msg); LOG.D ("Tttt", "SendMessage:" +Thread.CurrentThread (). GetName ());        }        }); Workerthread WT=NewWorkerthread ();    Wt.start (); }    classWorkerthreadextendsThread {@Override Public voidrun () {Super. Run ();            Looper.prepare (); Handler=NewHandler () {@Override Public voidhandlemessage (Message msg) {Super. Handlemessage (msg); LOG.D ("Tttt", "Handlemessage:" +Thread.CurrentThread (). GetName ()); inti =Msg.what; LOG.D ("Tttt", "Received Message object:" +i);            }            };        Looper.loop (); }    }}

Android Note (33) communication between Android threads (v) thread, Handle, Looper, and MessageQueue