AIDL

客户端
服务端
总结
源码地址

AIDL:Android Interface Definition Language,即Android接口定义语言。

服务端：

class MyService : Service() {    private val mList: MutableList<People> = mutableListOf()    override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {        return START_STICKY    }    override fun onBind(intent: Intent?): IBinder? {        return mBinder    }    private val mBinder = object : IMyAidlInterface.Stub() {        override fun getList(): MutableList<People> {            return mList        }        override fun add(people: People?) {            people?.apply {                mList.add(this)            }        }    }}

/**     * Constant to return from {@link #onStartCommand}: if this service's     * process is killed while it is started (after returning from     * {@link #onStartCommand}), then leave it in the started state but     * don't retain this delivered intent.  Later the system will try to     * re-create the service.  Because it is in the started state, it will     * guarantee to call {@link #onStartCommand} after creating the new     * service instance; if there are not any pending start commands to be     * delivered to the service, it will be called with a null intent     * object, so you must take care to check for this.     *      * This mode makes sense for things that will be explicitly started     * and stopped to run for arbitrary periods of time, such as a service     * performing background music playback.     */    public static final int START_STICKY = 1;

被杀后自动重启，保持启动状态，不保持Intent，重新调用onStartCommand，无新Intent则为空Intent—杀死重启后，不继续执行先前任务，能接受新任务。

IMyAidlInterface 就是自己定义得AIDL

package com.example.myservice;import com.example.myservice.IPeople;interface IMyAidlInterface {      void add(in People people);      List<People> getList();}

这里使用了自定义类People

package com.example.myservice;parcelable People;

这里必须使用parcelable
下面是People代码

package com.example.myserviceimport android.os.Parcelimport android.os.Parcelabledata class People(    var name: String? = "",    var id: Int = 1) : Parcelable {    constructor(source: Parcel) : this(        source.readString(),        source.readInt()    )    override fun describeContents() = 0    override fun writeToParcel(dest: Parcel, flags: Int) = with(dest) {        writeString(name)        writeInt(id)    }    companion object {        @JvmField        val CREATOR: Parcelable.Creator<People> = object : Parcelable.Creator<People> {            override fun createFromParcel(source: Parcel): People = People(source)            override fun newArray(size: Int): Array<People?> = arrayOfNulls(size)        }    }}

服务端代码就搞定了。
下面是客户端代码：

package com.example.myservice;import com.example.myservice.IPeople;interface IMyAidlInterface {     void add(in People people);     List<People> getList();}

必须和刚才服务端写得AIDL完全一样。注意包名

class MainActivity : AppCompatActivity() {    var mAidl: IMyAidlInterface? = null        override fun onCreate(savedInstanceState: Bundle?) {        super.onCreate(savedInstanceState)        setContentView(R.layout.activity_main)        bind()        btn.setOnClickListener {            mAidl?.add(People("名字", (0..10).random()))            tv.text = mAidl?.list.toString()        }    }    private fun bind() {        val intent = Intent()        intent.component = ComponentName("com.example.myservice", "com.example.myservice.MyService")        bindService(intent, mServiceConnection, Context.BIND_AUTO_CREATE)    }    private val mServiceConnection = object : ServiceConnection {        override fun onServiceConnected(name: ComponentName?, service: IBinder?) {            mAidl = IMyAidlInterface.Stub.asInterface(service)        }        override fun onServiceDisconnected(name: ComponentName?) {            mAidl = null        }    }    override fun onDestroy() {        super.onDestroy()        unbindService(mServiceConnection)    }}

客户端绑定服务代码。

客户端

获取aidl对象的方法

IMyAidlInterface.Stub.asInterface(service)

 /**     * Cast an IBinder object into an com.example.myservice.IMyAidlInterface interface,     * generating a proxy if needed.     */    public static com.example.myservice.IMyAidlInterface asInterface(android.os.IBinder obj)    {      if ((obj==null)) {        return null;      }      android.os.IInterface iin = obj.queryLocalInterface(DESCRIPTOR);      if (((iin!=null)&&(iin instanceof com.example.myservice.IMyAidlInterface))) {        return ((com.example.myservice.IMyAidlInterface)iin);      }      return new com.example.myservice.IMyAidlInterface.Stub.Proxy(obj);    }

/**     * Use information supplied to attachInterface() to return the     * associated IInterface if it matches the requested     * descriptor.     */    public @Nullable IInterface queryLocalInterface(@NonNull String descriptor) {        if (mDescriptor != null && mDescriptor.equals(descriptor)) {            return mOwner;        }        return null;    }

可以看出，如果本当前进程有直接返回当前进程得，如果没有，新建一个代理 Stub.Proxy

private static class Proxy implements com.example.myservice.IMyAidlInterface    {      private android.os.IBinder mRemote;      Proxy(android.os.IBinder remote)      {        mRemote = remote;      }   }

这里是Proxy得实现。

 @Override public void add(com.example.myservice.People people) throws android.os.RemoteException      {        //发送到服务端的数据         // 服务端返回的数据        android.os.Parcel _data = android.os.Parcel.obtain();        android.os.Parcel _reply = android.os.Parcel.obtain();        try {          _data.writeInterfaceToken(DESCRIPTOR);          if ((people!=null)) {            _data.writeInt(1);            people.writeToParcel(_data, 0);          }          else {            _data.writeInt(0);          }          //发送数据          boolean _status = mRemote.transact(Stub.TRANSACTION_add, _data, _reply, 0);          if (!_status && getDefaultImpl() != null) {            getDefaultImpl().add(people);            return;          }          _reply.readException();        }        finally {          _reply.recycle();          _data.recycle();        }      }

对应自定义个add方法。

 /**     * Default implementation rewinds the parcels and calls onTransact.  On     * the remote side, transact calls into the binder to do the IPC.     */    public final boolean transact(int code, @NonNull Parcel data, @Nullable Parcel reply,            int flags) throws RemoteException {        if (false) Log.v("Binder", "Transact: " + code + " to " + this);        if (data != null) {        //设置数据，调用native层            data.setDataPosition(0);        }        boolean r = onTransact(code, data, reply, flags);        if (reply != null) {            reply.setDataPosition(0);        }        return r;    }

这里是Binder传输数据的代码，里面调用了onTransact方法

服务端

object : IMyAidlInterface.Stub()

服务端获取IBinder

public static abstract class Stub extends android.os.Binder implements com.example.myservice.IMyAidlInterface

需要重写得两个方法

public void add(com.example.myservice.People people) throws android.os.RemoteException;public java.util.List<com.example.myservice.People> getList()   throws android.os.RemoteException;

通过这个onTransact方法调用

 case TRANSACTION_add:        {          data.enforceInterface(descriptor);          com.example.myservice.People _arg0;          if ((0!=data.readInt())) {            _arg0 = com.example.myservice.People.CREATOR.createFromParcel(data);          }          else {            _arg0 = null;          }          //调用add方法          this.add(_arg0);          reply.writeNoException();          return true;        }

这里面的add，就相当于客户端调用add方法后，把值传递过来。

总结

客户端是 Proxy 使用transact
中间是 Binder
服务端是 Stub 使用onTransact
AIDL_第1张图片

源码地址

https://github.com/jackwolf1/aidl

AIDL

AIDL

客户端

服务端

总结

源码地址

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