android aidl concept

Android AIDL ConceptCharlie Tsai @ Android Study Group

Charlie Tsai @ Android Study Groupcha122977@gmail.com

Software Engineer

Agenda

• Introduction of AIDL• Write your AIDL files• Implementation of AIDL

Introduction of AIDL

?AIDL?• Android Interface Definition Language• Main approach is IPC (Inter-Process

Communication)• Support types:

All primitive types, CharSequence & String, List & Map, Parcelable class

IPC Issue

Memories of Process A

Process B of Process BX

Cannot Access(Memory protection

by Kernel)

How AIDL solve IPC issue

Memories of Process A

Process B of Process B

Linux Kernel & Binder Driver

Access Access

Write Your AIDL File• Write *.aidl for your AIDL interface• You can turn your Parcelable Class into

AIDL• Include if you use Other AIDL

class/interface• Note:

List will become ArrayList in another sideMap will become HashMap in another side(WHY?)

AIDL Data StructureMyData.java

MyData.aidl

AIDL InterfaceIMyAidlInterface.aidl

How Parcelable Work

Stringint

Data in memory(order is matter)

Usages of AIDL

Export Your ServiceAllow to be bound

by other App.

Use Other’s ServiceCopy *.aidl file into your project

(Because you need to know this Interface)

Generated File by AIDL

• IInterface: Basic interface can be used for IPC• android.os.IBinder: Core class of IPC• Use YourInterface.asInterface(IBinder) to case

IBinder to YourInterface.• Use IBinder.queryLocalInterface() to know if this

IBinder is in local or remote.• If IBinder is in local, call function directly.• If IBinder is a remote object, use transact and

parcel to call function.

Let’s see the source code…

Questions?

固定聚會：每週三＠果子咖啡 (近捷運南京復興站 )技術分享：每月底週六 14:30 - 17:30以及眾多不定期活動 (ex: Workshop)

Thanks!