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);
}
}