新建 开辟线程的类，更加简洁方便

public class BackTaskRunner {
    private static final String TAG = "BackTaskRunner";
    private HandlerThread handlerThread;
    private Handler handler;

    private BackTaskRunner() {
        handlerThread = new HandlerThread(TAG);
        handlerThread.start();
        handler = new Handler(handlerThread.getLooper());
    }

    public static Handler getHandler() {
        return SingletonHolder.sRunner.handler;
    }

    private static class SingletonHolder {
        static BackTaskRunner sRunner = new BackTaskRunner();
    }
}

 BackTaskRunner.getHandler().post(new Runnable() {
            @Override
            public void run() {
                Logging.d(TAG, "pay() start UNPay");
                //最后一个参数： "01" 代表测试环境    "00" 代表正式环境
                UPPayAssistEx.startPay(activity,null,null,tn,payMode);
            }
        });