android.os.CancellationSignal#createTransport ( )源码实例Demo

@Override
public void layout(PrintAttributes oldAttributes, PrintAttributes newAttributes,
        ILayoutResultCallback callback, Bundle metadata, int sequence) {

    ICancellationSignal cancellationTransport = CancellationSignal.createTransport();
    try {
        callback.onLayoutStarted(cancellationTransport, sequence);
    } catch (RemoteException re) {
        // The spooler is dead - can't recover.
        Log.e(LOG_TAG, "Error notifying for layout start", re);
        return;
    }

    synchronized (mLock) {
        // If destroyed the handler is null.
        if (isDestroyedLocked()) {
            return;
        }

        CancellationSignal cancellationSignal = CancellationSignal.fromTransport(
                cancellationTransport);

        SomeArgs args = SomeArgs.obtain();
        args.arg1 = mDocumentAdapter;
        args.arg2 = oldAttributes;
        args.arg3 = newAttributes;
        args.arg4 = cancellationSignal;
        args.arg5 = new MyLayoutResultCallback(callback, sequence);
        args.arg6 = metadata;

        mHandler.obtainMessage(MyHandler.MSG_ON_LAYOUT, args).sendToTarget();
    }
}
 

@Override
public void write(PageRange[] pages, ParcelFileDescriptor fd,
        IWriteResultCallback callback, int sequence) {

    ICancellationSignal cancellationTransport = CancellationSignal.createTransport();
    try {
        callback.onWriteStarted(cancellationTransport, sequence);
    } catch (RemoteException re) {
        // The spooler is dead - can't recover.
        Log.e(LOG_TAG, "Error notifying for write start", re);
        return;
    }

    synchronized (mLock) {
        // If destroyed the handler is null.
        if (isDestroyedLocked()) {
            return;
        }

        CancellationSignal cancellationSignal = CancellationSignal.fromTransport(
                cancellationTransport);

        SomeArgs args = SomeArgs.obtain();
        args.arg1 = mDocumentAdapter;
        args.arg2 = pages;
        args.arg3 = fd;
        args.arg4 = cancellationSignal;
        args.arg5 = new MyWriteResultCallback(callback, fd, sequence);

        mHandler.obtainMessage(MyHandler.MSG_ON_WRITE, args).sendToTarget();
    }
}
 

@Override
public void onFillRequest(FillRequest request, IFillCallback callback) {
    ICancellationSignal transport = CancellationSignal.createTransport();
    try {
        callback.onCancellable(transport);
    } catch (RemoteException e) {
        e.rethrowFromSystemServer();
    }
    mHandler.sendMessage(obtainMessage(
            AutofillService::onFillRequest,
            AutofillService.this, request, CancellationSignal.fromTransport(transport),
            new FillCallback(callback, request.getId())));
}
 

@Override
public ICancellationSignal createCancellationSignal() {
    return CancellationSignal.createTransport();
}
 

@Override
public ICancellationSignal createCancellationSignal() {
    return CancellationSignal.createTransport();
}