android retrofit+rxjava 取消网络请求

private Disposable loginDisposable;
public void () {
    Retrofit retrofit = new Retrofit.Builder()
            .addConverterFactory(GsonConverterFactory.create())
            .addCallAdapterFactory(RxJava2CallAdapterFactory.create())
            .baseUrl("http://www.yeyuanxinyi.com/YeYuanXinYi")
            .build();
    HttpService service = retrofit.create(HttpService.class);
    Observable<Account> observable = service.login("yeyuanxinyi", "123456");
    observable.subscribeOn(Schedulers.io())
            .unsubscribeOn(Schedulers.io())
            .observeOn(AndroidSchedulers.mainThread())
            .subscribe(new Observer<Account>() {
                
                public void onSubscribe(Disposable d) {
                    
                    loginDisposable = d;
                }

                
                public void onNext(Account t) {

                }

                
                public void onError(Throwable e) {

                }

                
                public void onComplete() {

                }
            });
}

// 取消请求
private void cancelLogin() {
    if (loginDisposable != null && !loginDisposable.isDisposed()) {
        loginDisposable.dispose();
    }
}