Android Getting Started: interprocess communication through Aidl

First, Aidl introduction
Aidl:android Interface definition Language, Interface Definition language, as the name implies, is the language that defines the interface, that is, the interface can be defined using Aidl;
Aidl is simply a method of interprocess communication, similar to the RMI in Java;
Aidl uses the Xxx.aidl file to define the interface, usually placing the file in Com.xiazdong.aidl;
Aidl files are written similar to the authoring of interfaces, but there are some differences:
(1) No access modifiers (such as public, private, static, final) can be added before the interfaces and methods in Aidl; (2) Aidl supports method parameters in Java base type (3) Aidl If it is a non-Java basic type, add in, Out, InOut, (4) Aidl for the custom type, you need to implement the Parselable interface;
Aidl will automatically generate Java files in the Gen directory after writing;
In the automatically generated files we need to understand the methods are: (1) Xxx xx = Xxx.stub.asInterface (IBinder); //Convert IBinder type to AIDL type, used in Serviceconnection onserviceconnected;(2) Xxx.stub.fun (); //Call Aidl defined method

It should be noted that since the Aidl file is a bridge between the two applications, this document should exist in both applications.


second, the code case

Scene Description: This scenario is the same as the application function in the "Getting Started with Android: Binding to Service" article, where the addition service is applied in the Aidlservice, and the program that invokes the addition is in the Aidlclient application;
The effect is the same as before:



the different organizational structure of the program:



aidlclient Code

Addop.aidl

Package com.xiazdong.aidl;

Interface Addop {	//except without access, the other and interface definitions are almost
	int addService (int a,int b);
}

Mainactivity.java

Package com.xiazdong.aidlclient;

Import com.xiazdong.aidl.AddOp;
Import android.app.Activity;
Import Android.content.ComponentName;
Import android.content.Intent;
Import android.content.ServiceConnection;
Import Android.os.Bundle;
Import Android.os.IBinder;
Import android.os.RemoteException;
Import Android.view.View;
Import Android.view.View.OnClickListener;
Import Android.widget.Button;
Import Android.widget.EditText;

Import Android.widget.TextView;
	public class Mainactivity extends activity {private EditText op1,op2;
	Private button button;
	Private TextView result;
	Private Addop Binder;
	Private Serviceconnection conn = new addopserviceconnection ();
			Private Onclicklistener listener = new Onclicklistener () {@Override public void OnClick (View v) {int number = 0; try {number = Binder.addservice (Integer.parseint (Op1.gettext (). toString ()), Integer.parseint (Op2.gettext (). Tostrin
			g ()));
			catch (Exception e) {e.printstacktrace (); } result.settext ("ResUlt= "+number+");
	}
	};
        @Override public void OnCreate (Bundle savedinstancestate) {super.oncreate (savedinstancestate);
        Setcontentview (R.layout.main);
        OP1 = (edittext) This.findviewbyid (R.ID.OP1);
        OP2 = (edittext) This.findviewbyid (R.ID.OP2);
        result = (TextView) This.findviewbyid (R.id.result);
        Button = (button) This.findviewbyid (R.id.button);
        Button.setonclicklistener (listener);	Intent service = new Intent ("Com.xiazdong.action");
    Implicit Intent This.bindservice (service, Conn, bind_auto_create); Private class Addopserviceconnection implements serviceconnection{@Override public void onserviceconnected (Compone Ntname name, IBinder service) {binder = AddOp.Stub.asInterface (service);//convert IBinder to interface type} @Override public V
		OID onservicedisconnected (componentname name) {binder = null; }
	}
}

Aidlservice Code

Addop.aidl

Package com.xiazdong.aidl;

Interface Addop {
	int addService (int a,int b);
}

Addopservice.java

Package com.xiazdong.aidlservice;

Import com.xiazdong.aidl.AddOp;
Import Android.app.Service;
Import android.content.Intent;
Import Android.os.IBinder;
Import android.os.RemoteException;

public class Addopservice extends Service {
	private IBinder binder = new Addopbinder ();
	@Override public
	IBinder onbind (Intent Intent) {return
		binder;
	}
	public int Add (int a,int b) {//service-provided method is provided to the external return a+b via the binder object
		;
	}
	Private class Addopbinder extends addop.stub{	//inheritance aidl generated stub
		@Override public
		int AddService (int a, int b ) throws RemoteException {	//Implement this method return
			Add (a,b);	method to invoke service
		}}}