AndroidIPC机制Messenger实例详解-创新互联

Android IPC机制Messenger实例详解

前言：

Messenger可以翻译成信使，通过它可以在不同进程间传递Message对象有了它就可以轻松实现进程间的数据传递了。

Messenger使用的方法相对AIDL比较简单，它对AIDL做了一层封装是的我们不需要像采用AIDL那样去实现进程通信那么麻烦，可以看看他的源码有AIDL的迹象。

public final class Messenger implements Parcelable {
  private final IMessenger mTarget;

  public Messenger(Handler target) {
    mTarget = target.getIMessenger();
  }

  public void send(Message message) throws RemoteException {
    mTarget.send(message);
  }

  public IBinder getBinder() {
    return mTarget.asBinder();
  }

  public boolean equals(Object otherObj) {
    if (otherObj == null) {
      return false;
    }
    try {
      return mTarget.asBinder().equals(((Messenger)otherObj)
          .mTarget.asBinder());
    } catch (ClassCastException e) {
    }
    return false;
  }

  public int hashCode() {
    return mTarget.asBinder().hashCode();
  }

  public int describeContents() {
    return 0;
  }

  public void writeToParcel(Parcel out, int flags) {
    out.writeStrongBinder(mTarget.asBinder());
  }

  public static final Parcelable.Creator CREATOR
      = new Parcelable.Creator() {
    public Messenger createFromParcel(Parcel in) {
      IBinder target = in.readStrongBinder();
      return target != null ? new Messenger(target) : null;
    }

    public Messenger[] newArray(int size) {
      return new Messenger[size];
    }
  };

  public static void writeMessengerOrNullToParcel(Messenger messenger,
      Parcel out) {
    out.writeStrongBinder(messenger != null ? messenger.mTarget.asBinder()
        : null);
  }

  public static Messenger readMessengerOrNullFromParcel(Parcel in) {
    IBinder b = in.readStrongBinder();
    return b != null ? new Messenger(b) : null;
  }

  public Messenger(IBinder target) {
    mTarget = IMessenger.Stub.asInterface(target);
  }
}