Android featured 8--Local Service and remote service communication

About Remote Services

• A remote service refers to a service and a visitor that are not in the same application, that is, not in the same process.
• Access to remote services is similar to interprocess communication.
• Visitors and remote services need to comply with protocols that can be understood by the operating system, aidl.

1. On the server side and the client configuration Aidl

• Aidl files are best placed in the Aidl directory, aidl files are used for interface descriptions
• A Java file with the same name will be generated automatically
• In the automatically generated Java file, a stub class is automatically defined, inheriting the Binder class, implementing the interface described in the Aidl file

2. Writing Service business code

• Registering in the manifest file
• Implementing a custom IBinder

        <service android:name=". Studentservice">            <intent-filter >                <action android:name="  Com.njulya.REMOTESERVICE"/>            </intent-filter>        </service>

View Code

ImportCom.njulya.aidl.StudentQuery;ImportAndroid.app.Service;Importandroid.content.Intent;ImportAndroid.os.IBinder;Importandroid.os.RemoteException; Public classStudentserviceextendsService {IBinder ibinder; String[] Names= {"Zhang Yang", "Mr. Li Yongan", "Jay"}; @Override Publicibinder onbind (Intent Intent) {IBinder=NewStudentbinder (); returnIBinder; }/*** Implementation of IBinder interface for communication *@authorAndy*/    Private classStudentbinderextendsstudentquery.stub{@Override//interfaces described in the Aidl file         PublicString Query (intNothrowsRemoteException {returnNAMES[NO-1];//Business code        }            }}

View Code

3. Writing client applications

 Packagecom.njulya.remoteserviceclient;ImportCom.njulya.aidl.StudentQuery;Importandroid.app.Activity;ImportAndroid.content.ComponentName;Importandroid.content.Intent;Importandroid.content.ServiceConnection;ImportAndroid.os.Bundle;ImportAndroid.os.IBinder;Importandroid.os.RemoteException;ImportAndroid.view.Menu;ImportAndroid.view.View;ImportAndroid.widget.EditText;ImportAndroid.widget.TextView; Public classMainactivityextendsActivity {PrivateEditText StudentID; PrivateTextView content; PrivateStudentquery Studentquery; PrivateServiceconnection Conn; @Overrideprotected voidonCreate (Bundle savedinstancestate) {Super. OnCreate (savedinstancestate);        Setcontentview (R.layout.activity_main); StudentID= (EditText) This. Findviewbyid (r.id.student_id); Content= (TextView) This. Findviewbyid (r.id.content); Conn=Newstudentconnetion (); Intent Service=NewIntent ("Com.njulya.REMOTESERVICE");  This. Bindservice (Service, Conn, bind_auto_create); }    /*** Key to trigger business code *@paramv*/     Public voidQueryonclick (View v) {intNo =integer.valueof (Studentid.gettext (). toString ()); Try{String Studentname=studentquery.query (NO);        Content.settext (Studentname); } Catch(RemoteException e) {e.printstacktrace (); }    }    Private classStudentconnetionImplementsserviceconnection{@Override Public voidonserviceconnected (componentname name, IBinder service) {//To convert a IBinder proxy object to an interface typeStudentquery =StudentQuery.Stub.asInterface (service); } @Override Public voidonservicedisconnected (componentname name) {studentquery=NULL; }} @Overrideprotected voidOnDestroy () {unbindservice (conn); Super. OnDestroy (); } @Override Public BooleanOncreateoptionsmenu (Menu menu) {//inflate the menu; This adds items to the action bar if it is present.getmenuinflater (). Inflate (R.menu.main, menu); return true; }    }

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About local services

• The service started is running in the main thread, so the time-consuming operation is to create a new worker thread
• When using Bindservice, it is necessary to implement Serviceconnection,flags Bind_auto_create
• The key to the service is to return the implementation class object for IBinder, which uses some of the APIs in the service
• Typically get and close IBinder objects in a custom Serviceconnection implementation class
• Invoking the API in the service through the resulting IBinder object implementation

Business interface

Client code

 Packagecom.njulya.intsum;ImportAndroid.os.Bundle;ImportAndroid.os.IBinder;Importandroid.app.Activity;ImportAndroid.content.ComponentName;Importandroid.content.Intent;Importandroid.content.ServiceConnection;ImportAndroid.view.Menu;ImportAndroid.view.View;ImportAndroid.view.View.OnClickListener;ImportAndroid.widget.Button;ImportAndroid.widget.EditText;ImportAndroid.widget.TextView; Public classMainactivityextendsActivity {PrivateEditText NUM1; PrivateEditText num2; PrivateTextView sum; PrivateServiceconnection Conn; //custom public interface for the sum of two numbers    PrivateSumoftwo Sumoftwo; @Overrideprotected voidonCreate (Bundle savedinstancestate) {Super. OnCreate (savedinstancestate);        Setcontentview (R.layout.activity_main); NUM1= (EditText) This. Findviewbyid (R.ID.NUM1); Num2= (EditText) This. Findviewbyid (R.ID.NUM2); Sum= (TextView) This. Findviewbyid (R.id.sum); Button Button= (Button) This. Findviewbyid (R.id.button); Button.setonclicklistener (NewOnclicklistener () {@Override Public voidOnClick (View v) {sum ();        }        }); Conn=Newsumconnetion (); Intent Service=NewIntent ( This, Sumservice.class);  This. Bindservice (Service, Conn, bind_auto_create); }    protected voidsum () {intNumber1 =integer.valueof (Num1.gettext (). toString ()); intNumber2 =integer.valueof (Num2.gettext (). toString ()); intresult =sumoftwo.sum (Number1, number2);            Sum.settext (string.valueof (result)); }    Private classSumconnetionImplementsserviceconnection{@Override Public voidonserviceconnected (componentname name, IBinder service) {Sumoftwo=(sumoftwo) service; } @Override Public voidonservicedisconnected (componentname name) {Sumoftwo=NULL; }} @Overrideprotected voidOnDestroy () {unbindservice (conn); Super. OnDestroy (); } @Override Public BooleanOncreateoptionsmenu (Menu menu) {//inflate the menu; This adds items to the action bar if it is present.getmenuinflater (). Inflate (R.menu.main, menu); return true; }}

View CodeService-side code

 Packagecom.njulya.intsum;ImportAndroid.app.Service;Importandroid.content.Intent;ImportAndroid.os.Binder;ImportAndroid.os.IBinder; Public classSumserviceextendsService {@Override Publicibinder onbind (Intent Intent) {//TODO auto-generated Method Stub        return NewSumbinder (); }     Public classSumbinderextendsBinderImplementssumoftwo{@Override Public intSumintNumber1,intnumber2) {            returnNumber1 +number2; }            }}

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Android featured 8--Local Service and remote service communication