From Proxy-Stub to aidl

After understanding the cause and effect of the Proxy design mode and the design reason of the Proxy-Stub mode, let's take a look at the aidl service in Android service development. The previous example is still defined according to the AIDL syntax as follows:

IPlayer2.aidl

package com.sean.mp3player;interface IPlayer2 { void play(); void stop(); void getStatus();}

Use the aidl.exe tool to generate the IPlayer2.java interface as follows:

/* * This file is auto-generated.  DO NOT MODIFY. * Original file: /home/sean/workspace/MP3Player/src/com/sean/mp3player/IPlayer2.aidl */package com.sean.mp3player;public interface IPlayer2 extends android.os.IInterface{/** Local-side IPC implementation stub class. */public static abstract class Stub extends android.os.Binder implements com.sean.mp3player.IPlayer2{private static final java.lang.String DESCRIPTOR = "com.sean.mp3player.IPlayer2";/** Construct the stub at attach it to the interface. */public Stub(){this.attachInterface(this, DESCRIPTOR);}/** * Cast an IBinder object into an com.sean.mp3player.IPlayer2 interface, * generating a proxy if needed. */public static com.sean.mp3player.IPlayer2 asInterface(android.os.IBinder obj){if ((obj==null)) {return null;}android.os.IInterface iin = obj.queryLocalInterface(DESCRIPTOR);if (((iin!=null)&&(iin instanceof com.sean.mp3player.IPlayer2))) {return ((com.sean.mp3player.IPlayer2)iin);}return new com.sean.mp3player.IPlayer2.Stub.Proxy(obj);}@Override public android.os.IBinder asBinder(){return this;}@Override public boolean onTransact(int code, android.os.Parcel data, android.os.Parcel reply, int flags) throws android.os.RemoteException{switch (code){case INTERFACE_TRANSACTION:{reply.writeString(DESCRIPTOR);return true;}case TRANSACTION_play:{data.enforceInterface(DESCRIPTOR);this.play();reply.writeNoException();return true;}case TRANSACTION_stop:{data.enforceInterface(DESCRIPTOR);this.stop();reply.writeNoException();return true;}case TRANSACTION_getStatus:{data.enforceInterface(DESCRIPTOR);this.getStatus();reply.writeNoException();return true;}}return super.onTransact(code, data, reply, flags);}private static class Proxy implements com.sean.mp3player.IPlayer2{private android.os.IBinder mRemote;Proxy(android.os.IBinder remote){mRemote = remote;}@Override public android.os.IBinder asBinder(){return mRemote;}public java.lang.String getInterfaceDescriptor(){return DESCRIPTOR;}@Override public void play() throws android.os.RemoteException{android.os.Parcel _data = android.os.Parcel.obtain();android.os.Parcel _reply = android.os.Parcel.obtain();try {_data.writeInterfaceToken(DESCRIPTOR);mRemote.transact(Stub.TRANSACTION_play, _data, _reply, 0);_reply.readException();}finally {_reply.recycle();_data.recycle();}}@Override public void stop() throws android.os.RemoteException{android.os.Parcel _data = android.os.Parcel.obtain();android.os.Parcel _reply = android.os.Parcel.obtain();try {_data.writeInterfaceToken(DESCRIPTOR);mRemote.transact(Stub.TRANSACTION_stop, _data, _reply, 0);_reply.readException();}finally {_reply.recycle();_data.recycle();}}@Override public void getStatus() throws android.os.RemoteException{android.os.Parcel _data = android.os.Parcel.obtain();android.os.Parcel _reply = android.os.Parcel.obtain();try {_data.writeInterfaceToken(DESCRIPTOR);mRemote.transact(Stub.TRANSACTION_getStatus, _data, _reply, 0);_reply.readException();}finally {_reply.recycle();_data.recycle();}}}static final int TRANSACTION_play = (android.os.IBinder.FIRST_CALL_TRANSACTION + 0);static final int TRANSACTION_stop = (android.os.IBinder.FIRST_CALL_TRANSACTION + 1);static final int TRANSACTION_getStatus = (android.os.IBinder.FIRST_CALL_TRANSACTION + 2);}public void play() throws android.os.RemoteException;public void stop() throws android.os.RemoteException;public void getStatus() throws android.os.RemoteException;}

The java interface generated by the aidl interface looks very complex because all data types except the basic type, String, List, Map, and CharSequence need to be imported into the package, even in the same package, so the name looks very long.

However, if you observe the above Code carefully, you will find that,It is almost the same as the previous Proxy-Stub mode.. That is to say, the AIDL tool is used to generate a java interface that inherits the Proxy-Stub model from IBinder and implements the IPlayer. aidl interface.