android.os.NetworkOnMainThreadException在android上使用rxjava

Question

我无法实现rxJava以检查android上是否有互联网连接我这样做:

在我的启动器活动中,我在onCreate中有这个:

AndroidObservable.bindActivity(this,
            Observable.just(Utils.isActiveInternetConnection(Launcher.this)))
            .subscribeOn(Schedulers.newThread())
            .subscribe(new Action1<Boolean>() {
                @Override
                public void call(Boolean aBoolean) {
                    if (aBoolean) {
                        Toast.makeText(Launcher.this, "There is internet connection", Toast.LENGTH_SHORT).show();
                    } else {
                        Toast.makeText(Launcher.this, "There is no internet connection", Toast.LENGTH_SHORT).show();
                    }
                }
            });

我有一个Utils类,它是一个带有静态方法的final类,observable使用的方法是这样的:

    public static boolean isActiveInternetConnection(Context context) {
    if (isNetworkAvailable(context)) {
        try {
            HttpURLConnection urlc = (HttpURLConnection) (new URL("http://www.google.com").openConnection());
            urlc.setRequestProperty("User-Agent", "Test");
            urlc.setRequestProperty("Connection", "close");
            urlc.setConnectTimeout(1500);
            urlc.connect();
            return (urlc.getResponseCode() == 200);
        } catch (IOException e) {
            Log.e("network", "Error checking internet connection", e);
        }
    } else {
        Log.d("network", "No network available!");
    }
    return false;
}

private static boolean isNetworkAvailable(Context context){
    ConnectivityManager cm = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo activeNetwork = cm.getActiveNetworkInfo();
    if (null != activeNetwork) {
        return true;
    }
    else {
        return false;
    }
}

我收到android.os.NetworkOnMainThreadException,我找不到原因,提前谢谢.

Answer 1

Observable.just(...)在调用线程(主线程,在本例中)上立即调用.您的代码实际上只是这个的内联版本:

boolean activeConn = Utils.isActiveInternetConnection(Launcher.this);
AndroidObservable.bindActivity(this, 
        Observable.just(activeConn))
        .subscribeOn(...)
        ...

您已经尝试通过调用将其从主线程移开subscribeOn()- 但是调用已经发生了.

我们处理这个问题的方式(我不确定这是最好的方法,但它确实有效)是推迟网络或阻塞调用直到订阅发生,设置observable以在正确的线程上运行,然后订阅:

AndroidObservable.bindActivity(this,
        Observable.defer(new Func0<Boolean>() {
            @Override
            public Observable<Observable<Boolean>> call() {
                return Observable.just(Utils.isActiveInternetConnection(Launcher.this));
            }
        })
        .subscribeOn(Schedulers.io())
        .observeOn(AndroidSchedulers.mainThread())
        .subscribe(new Action1<Boolean>() {
            @Override
            public void call(Boolean aBoolean) {
                if (aBoolean) {
                    Toast.makeText(Launcher.this, "There is internet connection", Toast.LENGTH_SHORT).show();
                } else {
                    Toast.makeText(Launcher.this, "There is no internet connection", Toast.LENGTH_SHORT).show();
                }
            }
        });

Answer 2

我想just只是同步调用该方法，因为它需要布尔值并尝试获取它。

我不太擅长，RxJava但你可以尝试这样的事情：

Observable<Boolean> onlineObservable = Observable.create(new Observable.OnSubscribe<Boolean>() {
    @Override
    public void call(Subscriber subscriber) {
        subscriber.onNext(Utils.isActiveInternetConnection(context));
    }
});
onlineObservable.subscribeOn(Schedulers.newThread()).subscribe(result -> {...});