bindservice流程

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bindservice流程

• android.app.ContextImpl#bindService

  @Override
  public boolean bindService(Intent service, ServiceConnection conn,
          int flags) {
      warnIfCallingFromSystemProcess();
      return bindServiceCommon(service, conn, flags, mMainThread.getHandler(),
              Process.myUserHandle());
  }
  
  private boolean bindServiceCommon(Intent service, ServiceConnection conn, int flags, Handler
          handler, UserHandle user) {
      IServiceConnection sd;
      if (conn == null) {
          throw new IllegalArgumentException("connection is null");
      }
      if (mPackageInfo != null) {
          sd = mPackageInfo.getServiceDispatcher(conn, getOuterContext(), handler, flags);
      } else {
          throw new RuntimeException("Not supported in system context");
      }
      validateServiceIntent(service);
      try {
          IBinder token = getActivityToken();
          if (token == null && (flags&BIND_AUTO_CREATE) == 0 && mPackageInfo != null
                  && mPackageInfo.getApplicationInfo().targetSdkVersion
                  < android.os.Build.VERSION_CODES.ICE_CREAM_SANDWICH) {
              flags |= BIND_WAIVE_PRIORITY;
          }
          service.prepareToLeaveProcess(this);
          // 1. 这里是调用了服务端的bindService
          int res = ActivityManagerNative.getDefault().bindService(
              mMainThread.getApplicationThread(), getActivityToken(), service,
              service.resolveTypeIfNeeded(getContentResolver()),
              sd, flags, getOpPackageName(), user.getIdentifier());
          if (res < 0) {
              throw new SecurityException(
                      "Not allowed to bind to service " + service);
          }
          return res != 0;
      } catch (RemoteException e) {
          throw e.rethrowFromSystemServer();
      }
  }
  

• ActivityManagerProxy代理的真正的是ActivityManagerNative子类ActivityManagerService

• android.app.ActivityManagerProxy#bindService

  public int bindService(IApplicationThread caller, IBinder token,
          Intent service, String resolvedType, IServiceConnection connection,
          int flags,  String callingPackage, int userId) throws RemoteException {
      Parcel data = Parcel.obtain();
      Parcel reply = Parcel.obtain();
      data.writeInterfaceToken(IActivityManager.descriptor);
      data.writeStrongBinder(caller != null ? caller.asBinder() : null);
      data.writeStrongBinder(token);
      service.writeToParcel(data, 0);
      data.writeString(resolvedType);
      data.writeStrongBinder(connection.asBinder());
      data.writeInt(flags);
      data.writeString(callingPackage);
      data.writeInt(userId);
      // 2. 代理调接口跟服务端通信,这里走到服务端
      mRemote.transact(BIND_SERVICE_TRANSACTION, data, reply, 0);
      reply.readException();
      int res = reply.readInt();
      data.recycle();
      reply.recycle();
      return res;
  }
  

• public abstract class ActivityManagerNative extends Binder implements IActivityManager

  @Override
  public boolean onTransact(int code, Parcel data, Parcel reply, int flags)
          throws RemoteException {
      // 4. 子类调用了父类的onTransact
      case BIND_SERVICE_TRANSACTION: {
          data.enforceInterface(IActivityManager.descriptor);
          IBinder b = data.readStrongBinder();
          IApplicationThread app = ApplicationThreadNative.asInterface(b);
          IBinder token = data.readStrongBinder();
          Intent service = Intent.CREATOR.createFromParcel(data);
          String resolvedType = data.readString();
          b = data.readStrongBinder();
          int fl = data.readInt();
          String callingPackage = data.readString();
          int userId = data.readInt();
          IServiceConnection conn = IServiceConnection.Stub.asInterface(b);
          // 5. 这里调用了子类中的bindService不是代理类中的
          int res = bindService(app, token, service, resolvedType, conn, fl,
                  callingPackage, userId);
          reply.writeNoException();
          reply.writeInt(res);
          return true;
      }
  }
  

• com.android.server.am.ActivityManagerService extends ActivityManagerNative

  @Override
  public boolean onTransact(int code, Parcel data, Parcel reply, int flags)
          throws RemoteException {
      try {
          // 3. 这里会调用父类的onTransact方法
          return super.onTransact(code, data, reply, flags);
      } catch (RuntimeException e) {
          // The activity manager only throws security exceptions, so let's
          // log all others.
          if (!(e instanceof SecurityException)) {
              Slog.wtf(TAG, "Activity Manager Crash", e);
          }
          throw e;
      }
  }
  
  public int bindService(IApplicationThread caller, IBinder token, Intent service,
      String resolvedType, IServiceConnection connection, int flags, String callingPackage,
      int userId) throws TransactionTooLargeException {
      enforceNotIsolatedCaller("bindService");
  
      // 6. 执行绑定服务的操作
      synchronized(this) {
          return mServices.bindServiceLocked(caller, token, service,
                  resolvedType, connection, flags, callingPackage, userId);
      }
  }
  

总结:

• 1.ContextImpl#bindService
• 2.ActivityManagerNative.getDefault().bindService
• 3.ActivityManagerProxy#bindService —> mRemote.transact
• 4.ActivityManagerService.onTransact
• 5.ActivityManagerNative.onTransact
• 6.调用子类的bindService即ActivityManagerService.bindService