Use of the Messenger class

First, the Messenger class

Function: Similar to the message class, but is used across processes.

Analysis: Its bottom layer is implemented by AIDL, from the construction method can be seen

Service usage

Public Messenger (Handler target) {

Mtarget = Target.getimessenger ();

}

Client Side use

Public Messenger (IBinder Targer) {

Mtarget = IMessenger.Stub.asInterface (target);

}

Second, use (Service and client send each other information)

Step one: Create Messenger on the service side

 Public classBookserviceextendsService {Private Static FinalString TAG = "Bookservice"; //①: Create handler to prepare for Messenger creation    PrivateHandler Mhandler =NewHandler () {@Override Public voidhandlemessage (Message msg) {Super. Handlemessage (msg); Switch(msg.what) { Case0:                    //when the client sends the message, the output
Bundle bundle = Msg.getdata (); LOG.D (TAG, "service received message" +bundle.getstring ("MSG"));  Break;   }        }    }; //②: Create Messenger    PrivateMessenger Mmessenger =NewMessenger (Mhandler); @Override Public voidonCreate () {Super. OnCreate (); } @Override Publicibinder onbind (Intent Intent) {//③: Returns the binder of the Messenger object to the client        returnMmessenger.getbinder (); }}    

Step two: Client side receive Messenger send message to service side

 Public classMainactivityextendsappcompatactivity {Private Static FinalString TAG = "Mainactivity"; PrivateMessenger Mservice; @Overrideprotected voidonCreate (Bundle savedinstancestate) {Super. OnCreate (savedinstancestate);        Setcontentview (R.layout.activity_main); Serviceconnection Connection=Newserviceconnection () {@Override Public voidonserviceconnected (componentname name, IBinder service) {//re-create MessengerMservice =NewMessenger (service); //get the message from the MSG poolMessage msg = Message.obtain (NULL, 0); //Create BundlesBundle bundle =NewBundle (); Bundle.putstring ("MSG", "Hello,nice to meet"); //to load bundles into a message objectMsg.setdata (bundle); Try {                    //Sends a message to the server, stating that the message inherits the Parcelable interfacemservice.send (msg); } Catch(RemoteException e) {e.printstacktrace (); }} @Override Public voidonservicedisconnected (componentname name) {}}; Intent Intent=NewIntent ( This, Bookservice.class);    Bindservice (Intent, connection, bind_auto_create); }

Step three: Implement the server to send information to the client two-way communication

//Client Side/*** Step One: Create a message sent by the handler receiving server.*/    PrivateHandler Mhandler =NewHandler () {@Override Public voidhandlemessage (Message msg) {Super. Handlemessage (msg); Switch(msg.what) { Case0: Bundle Bundle=Msg.getdata (); LOG.D (TAG,"Client received message:" +bundle.getstring ("Replydata")));  Break; }        }    };/*** Step Two: Add in public void onserviceconnected (componentname name, IBinder service) method*/Msg.replyto= Mservice;

/** handler in the *service end */ // receive Messenger        sent from client in handler Messenger messenger = msg.replyto;          // Create msg         Message replymessage = Message.obtain (null, 0);          Try {           // send msg back to client          messenger.send (replymessage);          Catch (RemoteException e) {                 e.printstacktrace ();         }

Flow chart

Use of the Messenger class