Binder系列9—如何使用AIDL

copy from: http://gityuan.com/2015/11/23/binder-aidl/

自定义binder架构的 client/ server组件

一、AIDL

1.1 Server端

RemoteService.java

本例是为了演示进程间的通信机制，故需要将Service与Activity处于不同的进程，需要在AndroidManifest.xml中，把service配置成android:process=":remote",进程也可以命名成其他的。

 
  public class RemoteService extends Service { private static final String TAG = "BinderSimple"; MyData mMyData; @Override public void onCreate() { super.onCreate(); Log.i(TAG, "[RemoteService] onCreate"); initMyData(); } @Override public IBinder onBind(Intent intent) { Log.i(TAG,"[RemoteService] onBind"); return mBinder; } @Override public boolean onUnbind(Intent intent) { Log.i(TAG, "[RemoteService] onUnbind"); return super.onUnbind(intent); } @Override public void onDestroy() { Log.i(TAG, "[RemoteService] onDestroy"); super.onDestroy(); } /** * 实现IRemoteService.aidl中定义的方法 */ private final IRemoteService.Stub mBinder = new IRemoteService.Stub() { @Override public int getPid() throws RemoteException { Log.i(TAG,"[RemoteService] getPid()="+android.os.Process.myPid()); return android.os.Process.myPid(); } @Override public MyData getMyData() throws RemoteException { Log.i(TAG,"[RemoteService] getMyData() "+ mMyData.toString()); return mMyData; } /**此处可用于权限拦截**/ @Override public boolean onTransact(int code, Parcel data, Parcel reply, int flags) throws RemoteException { return super.onTransact(code, data, reply, flags); } }; /** * 初始化MyData数据 **/ private void initMyData() { mMyData = new MyData(); mMyData.setData1(10); mMyData.setData2(20); } }  
 

1.2 Client端

ClientActivity.java

public class ClientActivity extends AppCompatActivity { private static final String TAG = "BinderSimple"; private IRemoteService mRemoteService; private boolean mIsBound; private TextView mCallBackTv; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); Log.i(TAG, "[ClientActivity] onCreate"); setContentView(R.layout.activity_main); mCallBackTv = (TextView) findViewById(R.id.tv_callback); mCallBackTv.setText(R.string.remote_service_unattached); } /** * 用语监控远程服务连接的状态 */ private ServiceConnection mConnection = new ServiceConnection() { @Override public void onServiceConnected(ComponentName name, IBinder service) { mRemoteService = IRemoteService.Stub.asInterface(service); String pidInfo = null; try { MyData myData = mRemoteService.getMyData(); pidInfo = "pid="+ mRemoteService.getPid() + ", data1 = "+ myData.getData1() + ", data2="+ myData.getData2(); } catch (RemoteException e) { e.printStackTrace(); } Log.i(TAG, "[ClientActivity] onServiceConnected "+pidInfo); mCallBackTv.setText(pidInfo); Toast.makeText(ClientActivity.this, R.string.remote_service_connected, Toast.LENGTH_SHORT).show(); } @Override public void onServiceDisconnected(ComponentName name) { Log.i(TAG, "[ClientActivity] onServiceDisconnected"); mCallBackTv.setText(R.string.remote_service_disconnected); mRemoteService = null; Toast.makeText(ClientActivity.this, R.string.remote_service_disconnected, Toast.LENGTH_SHORT).show(); } }; public void clickHandler(View view){ switch (view.getId()){ case R.id.btn_bind: bindRemoteService(); break; case R.id.btn_unbind: unbindRemoteService(); break; case R.id.btn_kill: killRemoteService(); break; } } /** * 绑定远程服务 */ private void bindRemoteService(){ Log.i(TAG, "[ClientActivity] bindRemoteService"); Intent intent = new Intent(ClientActivity.this, RemoteService.class); intent.setAction(IRemoteService.class.getName()); bindService(intent, mConnection, Context.BIND_AUTO_CREATE); mIsBound = true; mCallBackTv.setText(R.string.binding); } /** * 解除绑定远程服务 */ private void unbindRemoteService(){ if(!mIsBound){ return; } Log.i(TAG, "[ClientActivity] unbindRemoteService ==>"); unbindService(mConnection); mIsBound = false; mCallBackTv.setText(R.string.unbinding); } /** * 杀死远程服务 */ private void killRemoteService(){ Log.i(TAG, "[ClientActivity] killRemoteService"); try { android.os.Process.killProcess(mRemoteService.getPid()); mCallBackTv.setText(R.string.kill_success); } catch (RemoteException e) { e.printStackTrace(); Toast.makeText(ClientActivity.this, R.string.kill_failure, Toast.LENGTH_SHORT).show(); } } }

1.3 AIDL文件

(1)IRemoteService.aidl 定义远程通信的接口方法

 
  interface IRemoteService {
    int getPid(); MyData getMyData(); }

(2)MyData.aidl 定义远程通信的自定义数据

parcelable MyData;

1.4 Parcel数据

MyData.java

public class MyData implements Parcelable { private int data1; private int data2; public MyData(){ } protected MyData(Parcel in) { readFromParcel(in); } public static final Creator<MyData> CREATOR = new Creator<MyData>() { @Override public MyData createFromParcel(Parcel in) { return new MyData(in); } @Override public MyData[] newArray(int size) { return new MyData[size]; } }; @Override public int describeContents() { return 0; } /** 将数据写入到Parcel **/ @Override public void writeToParcel(Parcel dest, int flags) { dest.writeInt(data1); dest.writeInt(data2); } /** 从Parcel中读取数据 **/ public void readFromParcel(Parcel in){ data1 = in.readInt(); data2 = in.readInt(); } public int getData2() { return data2; } public void setData2(int data2) { this.data2 = data2; } public int getData1() { return data1; } public void setData1(int data1) { this.data1 = data1; } @Override public String toString() { return "data1 = "+ data1 + ", data2="+ data2; } }

1.5 运行

该工程会生成一个apk，安装到手机，打开apk，界面如下：

apk

界面上有三个按钮，分别是功能分别是bindService(绑定Service), unbindService(解除绑定Service), killProcess(杀死Service进程)。

从左往右，依次点击界面，可得：

apk

二、原理分析

调用图：

aidl image

2.1 源码

采用AIDL技术，是原理还是利用framework binder的架构。本文的实例AIDL会自动生成一个与之相对应的IRemoteService.java文件，如下：

package com.gityuan.appbinderdemo;
public interface IRemoteService extends android.os.IInterface { public static abstract class Stub extends android.os.Binder implements com.gityuan.appbinderdemo.IRemoteService { private static final java.lang.String DESCRIPTOR = "com.gityuan.appbinderdemo.IRemoteService"; /** * Stub构造函数 */ public Stub() { this.attachInterface(this, DESCRIPTOR); } /** * 将IBinder 转换为IRemoteService interface */ public static com.gityuan.appbinderdemo.IRemoteService asInterface(android.os.IBinder obj) { if ((obj == null)) { return null; } android.os.IInterface iin = obj.queryLocalInterface(DESCRIPTOR); if (((iin != null) && (iin instanceof com.gityuan.appbinderdemo.IRemoteService))) { return ((com.gityuan.appbinderdemo.IRemoteService) iin); } return new com.gityuan.appbinderdemo.IRemoteService.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_getPid: { data.enforceInterface(DESCRIPTOR); int _result = this.getPid(); reply.writeNoException(); reply.writeInt(_result); return true; } case TRANSACTION_getMyData: { data.enforceInterface(DESCRIPTOR); com.gityuan.appbinderdemo.MyData _result = this.getMyData(); reply.writeNoException(); if ((_result != null)) { reply.writeInt(1); _result.writeToParcel(reply, android.os.Parcelable.PARCELABLE_WRITE_RETURN_VALUE); } else { reply.writeInt(0); } return true; } } return super.onTransact(code, data, reply, flags); } private static class Proxy implements com.gityuan.appbinderdemo.IRemoteService { private android.os.IBinder mRemote; /** * Proxy构造函数 */ Proxy(android.os.IBinder remote) { mRemote = remote; } @Override public android.os.IBinder asBinder() { return mRemote; } public java.lang.String getInterfaceDescriptor() { return DESCRIPTOR; } @Override public int getPid() throws android.os.RemoteException { android.os.Parcel _data = android.os.Parcel.obtain(); android.os.Parcel _reply = android.os.Parcel.obtain(); int _result; try { _data.writeInterfaceToken(DESCRIPTOR); mRemote.transact(Stub.TRANSACTION_getPid, _data, _reply, 0); _reply.readException(); _result = _reply.readInt(); } finally { _reply.recycle(); _data.recycle(); } return _result; } @Override public com.gityuan.appbinderdemo.MyData getMyData() throws android.os.RemoteException { android.os.Parcel _data = android.os.Parcel.obtain(); android.os.Parcel _reply = android.os.Parcel.obtain(); com.gityuan.appbinderdemo.MyData _result; try { _data.writeInterfaceToken(DESCRIPTOR); mRemote.transact(Stub.TRANSACTION_getMyData, _data, _reply, 0); _reply.readException(); if ((0 != _reply.readInt())) { _result = com.gityuan.appbinderdemo.MyData.CREATOR.createFromParcel(_reply); } else { _result = null; } } finally { _reply.recycle(); _data.recycle(); } return _result; } } static final int TRANSACTION_getPid = (android.os.IBinder.FIRST_CALL_TRANSACTION + 0); static final int TRANSACTION_getMyData = (android.os.IBinder.FIRST_CALL_TRANSACTION + 1); } public int getPid() throws android.os.RemoteException; public com.gityuan.appbinderdemo.MyData getMyData() throws android.os.RemoteException; }