2018-08-14
AIDL 创建一个接口，再里面定义方法 package com.example.taidl; interface ICalcAIDL { int add(int x , int y); int min(int x , int y ); } build一下gen目录下会生成ICalcAIDL.java文件 /* * This file is auto-generated. DO NOT MODIFY. * Original file: /Users/dream/Downloads/android/androidProject/TAIDL/src/com/example/taidl/ICalcAIDL.aidl */ package com.example.taidl; public interface ICalcAIDL extends android.os.IInterface { /** Local-side IPC implementation stub class. */ public static abstract class Stub extends android.os.Binder implements com.example.taidl.ICalcAIDL { private static final java.lang.String DESCRIPTOR = "com.example.taidl.ICalcAIDL"; /** Construct the stub at attach it to the interface. */ public Stub() { this.attachInterface(this, DESCRIPTOR); } /** * Cast an IBinder object into an com.example.taidl.ICalcAIDL interface, * generating a proxy if needed. */ public static com.example.taidl.ICalcAIDL asInterface(android.os.IBinder obj) { if ((obj==null)) { return null; } android.os.IInterface iin = obj.queryLocalInterface(DESCRIPTOR); if (((iin!=null)&&(iin instanceof com.example.taidl.ICalcAIDL))) { return ((com.example.taidl.ICalcAIDL)iin); } return new com.example.taidl.ICalcAIDL.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_add: { data.enforceInterface(DESCRIPTOR); int _arg0; _arg0 = data.readInt(); int _arg1; _arg1 = data.readInt(); int _result = this.add(_arg0, _arg1); reply.writeNoException(); reply.writeInt(_result); return true; } case TRANSACTION_min: { data.enforceInterface(DESCRIPTOR); int _arg0; _arg0 = data.readInt(); int _arg1; _arg1 = data.readInt(); int _result = this.min(_arg0, _arg1); reply.writeNoException(); reply.writeInt(_result); return true; } } return super.onTransact(code, data, reply, flags); } private static class Proxy implements com.example.taidl.ICalcAIDL { 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 int add(int x, int y) 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); _data.writeInt(x); _data.writeInt(y); mRemote.transact(Stub.TRANSACTION_add, _data, _reply, 0); _reply.readException(); _result = _reply.readInt(); } finally { _reply.recycle(); _data.recycle(); } return _result; } @Override public int min(int x, int y) 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); _data.writeInt(x); _data.writeInt(y); mRemote.transact(Stub.TRANSACTION_min, _data, _reply, 0); _reply.readException(); _result = _reply.readInt(); } finally { _reply.recycle(); _data.recycle(); } return _result; } } static final int TRANSACTION_add = (android.os.IBinder.FIRST_CALL_TRANSACTION + 0); static final int TRANSACTION_min = (android.os.IBinder.FIRST_CALL_TRANSACTION + 1); } public int add(int x, int y) throws android.os.RemoteException; public int min(int x, int y) throws android.os.RemoteException; } 新建一个Service package com.example.taidl; import android.app.Service; import android.content.Intent; import android.os.IBinder; import android.os.RemoteException; import android.util.Log; public class CalcService extends Service{ private static final String TAG = "server"; public void onCreate() { Log.e(TAG, "onCreate"); } public IBinder onBind(Intent t) { Log.e(TAG, "onBind"); return mBinder; } public void onDestroy() { Log.e(TAG, "onDestroy"); super.onDestroy(); } public boolean onUnbind(Intent intent) { Log.e(TAG, "onUnbind"); return super.onUnbind(intent); } public void onRebind(Intent intent) { Log.e(TAG, "onRebind"); super.onRebind(intent); } private final ICalcAIDL.Stub mBinder = new ICalcAIDL.Stub() { @Override public int min(int x, int y) throws RemoteException { return x + y; } @Override public int add(int x, int y) throws RemoteException { // TODO Auto-generated method stub return x - y; } }; } 创建了一个mBinder对象，并在Service的onBind方法中返回 注册： <service android:name="com.example.taidl.CalcService"> <intent-filter> <action android:name="com.example.taidl.calc" /> <category android:name="android.intent.category.DEFAULT" /> </intent-filter> </service> 我们一会会在别的应用程序中通过Intent来查找此Service；这个不需要Activity，所以我也就没写Activity，安装完成也看不到安装图标，悄悄在后台运行着。服务端编写完毕。下面开始编写客户端: package com.example.tclient; import com.example.taidl.ICalcAIDL; import android.app.Activity; import android.content.ComponentName; import android.content.Context; import android.content.Intent; import android.content.ServiceConnection; import android.os.Bundle; import android.os.IBinder; import android.util.Log; import android.view.View; import android.widget.Toast; public class MainActivity extends Activity { private ICalcAIDL mCalcAidl; private ServiceConnection mServiceConn = new ServiceConnection() { @Override public void onServiceDisconnected(ComponentName name) { Log.e("client", "onServiceDisconnected"); mCalcAidl = null; } @Override public void onServiceConnected(ComponentName name, IBinder service) { Log.e("client", "onServiceConnected"); mCalcAidl = ICalcAIDL.Stub.asInterface(service); } }; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); } /** * 点击BindService按钮时调用 * @param view */ public void bindService(View view) { Intent intent = new Intent(); intent.setAction("com.example.taidl.calc"); bindService(intent, mServiceConn, Context.BIND_AUTO_CREATE); } /** * 点击unBindService按钮时调用 * @param view */ public void unbindService(View view) { unbindService(mServiceConn); } /** * 点击12+12按钮时调用 * @param view */ public void addInvoked(View view) throws Exception { if (mCalcAidl != null) { int addRes = mCalcAidl.add(12, 12); Toast.makeText(this, addRes + "", Toast.LENGTH_SHORT).show(); } else { Toast.makeText(this, "服务器被异常杀死，请重新绑定服务端", Toast.LENGTH_SHORT) .show(); } } /** * 点击50-12按钮时调用 * @param view */ public void minInvoked(View view) throws Exception { if (mCalcAidl != null) { int addRes = mCalcAidl.min(50, 12); Toast.makeText(this, addRes + "", Toast.LENGTH_SHORT).show(); } else { Toast.makeText(this, "服务器未绑定或被异常杀死，请重新绑定服务端", Toast.LENGTH_SHORT) .show(); } } } 将服务端的aidl文件完整的复制过来，包名一定要一致。 分析AIDL生成的代码 服务端 private final ICalcAIDL.Stub mBinder = new ICalcAIDL.Stub() { @Override public int add(int x, int y) throws RemoteException { return x + y; } @Override public int min(int x, int y) throws RemoteException { return x - y; } }; ICalcAILD.Stub来执行的，让我们来看看Stub这个类的声明： public static abstract class Stub extends android.os.Binder implements com.zhy.calc.aidl.ICalcAIDL 清楚的看到这个类是Binder的子类，是不是符合我们文章开通所说的服务端其实是一个Binder类的实例 接下来看它的onTransact()方法： @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_add: { data.enforceInterface(DESCRIPTOR); int _arg0; _arg0 = data.readInt(); int _arg1; _arg1 = data.readInt(); int _result = this.add(_arg0, _arg1); reply.writeNoException(); reply.writeInt(_result); return true; } case TRANSACTION_min: { data.enforceInterface(DESCRIPTOR); int _arg0; _arg0 = data.readInt(); int _arg1; _arg1 = data.readInt(); int _result = this.min(_arg0, _arg1); reply.writeNoException(); reply.writeInt(_result); return true; } } return super.onTransact(code, data, reply, flags); } 文章开头也说到服务端的Binder实例会根据客户端依靠Binder驱动发来的消息，执行onTransact方法，然后由其参数决定执行服务端的代码。 可以看到onTransact有四个参数 code ， data ，replay ， flags code 是一个整形的唯一标识，用于区分执行哪个方法，客户端会传递此参数，告诉服务端执行哪个方法 data客户端传递过来的参数 replay服务器返回回去的值 flags标明是否有返回值，0为有（双向），1为没有（单向） 我们仔细看case TRANSACTION_min中的代码 data.enforceInterface(DESCRIPTOR); 与客户端的writeInterfaceToken对用，标识远程服务的名称 int _arg0; _arg0 = data.readInt(); int _arg1; _arg1 = data.readInt(); 接下来分别读取了客户端传入的两个参数 int _result = this.min(_arg0, _arg1); reply.writeNoException(); reply.writeInt(_result); 然后执行this.min，即我们实现的min方法；返回result由reply写回。 add同理，可以看到服务端通过AIDL生成Stub的类，封装了服务端本来需要写的代码。 客户端 客户端主要通过ServiceConnected与服务端连接 private ServiceConnection mServiceConn = new ServiceConnection() { @Override public void onServiceDisconnected(ComponentName name) { Log.e("client", "onServiceDisconnected"); mCalcAidl = null; } @Override public void onServiceConnected(ComponentName name, IBinder service) { Log.e("client", "onServiceConnected"); mCalcAidl = ICalcAIDL.Stub.asInterface(service); } }; 如果你比较敏锐，应该会猜到这个onServiceConnected中的IBinder实例，其实就是我们文章开通所说的Binder驱动，也是一个Binder实例 在ICalcAIDL.Stub.asInterface中最终调用了： return new com.zhy.calc.aidl.ICalcAIDL.Stub.Proxy(obj); 这个Proxy实例传入了我们的Binder驱动，并且封装了我们调用服务端的代码，文章开头说，客户端会通过Binder驱动的transact()方法调用服务端代码 直接看Proxy中的add方法 @Override public int add(int x, int y) 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); _data.writeInt(x); _data.writeInt(y); mRemote.transact(Stub.TRANSACTION_add, _data, _reply, 0); _reply.readException(); _result = _reply.readInt(); } finally { _reply.recycle(); _data.recycle(); } return _result; } 首先声明两个Parcel对象，一个用于传递数据，一个用户接收返回的数据 _data.writeInterfaceToken(DESCRIPTOR);与服务器端的enforceInterfac对应 _data.writeInt(x); _data.writeInt(y);写入需要传递的参数 mRemote.transact(Stub.TRANSACTION_add, _data, _reply, 0); 终于看到了我们的transact方法，第一个对应服务端的code,_data,_repay分别对应服务端的data，reply，0表示是双向的 _reply.readException(); _result = _reply.readInt(); 最后读出我们服务端返回的数据，然后return。可以看到和服务端的onTransact基本是一行一行对应的。 我们已经通过AIDL生成的代码解释了Android Binder框架的工作原理。Service的作用其实就是为我们创建Binder驱动，即服务端与客户端连接的桥梁。
