Question

我有一个严重的问题，我无法解决问题我需要对令牌进行身份验证才能让用户登录我的应用程序，问题是即使我使用AsyncTask，也可能因为它，我无法及时对其进行身份验证。其他问题，有时苛刻，我得到NetworkOnMainThreadException错误...我真的没希望。

这是流程 -

Check for existsing token -> Validate -> Move to next activity

这是我的代码 -

    public boolean validateToken(TokenAccess token) {
    new IsValid().execute(token);
    return isValid;
}

private class IsValid extends AsyncTask<TokenAccess, Void, Boolean> {

    @Override
    protected Boolean doInBackground(TokenAccess... params) {
        TokenAccess token = params[0];
        switch (token.getSource().getSource()) {
        case 'M':
            new UrlDownloader(new UrlDownloader.DownloadListener() {

                @Override
                public void setRequest(HttpRequest request) {}

                @Override
                public void onRecive(String content) {
                    if (content.contains("stats")) {
                        isValid = true;
                    } else {
                        isValid = false;
                    }

                }

                @Override
                public void onError(Exception e) {}

            }, UrlDownloader.RequestType.GET)
                    .execute("https://api.meetup.com/dashboard?access_token="
                            + token.getToken());
        }
        return isValid;
    }

}

这是URLDownloader类 -

public class UrlDownloader extends AsyncTask<String, Void, HttpResponse> {

    public static final String TAG = "net.ytsweb.socigo.assests.UrlDownloader";

    public enum RequestType {
        GET, POST;
    }

    private RequestType type;
    private DownloadListener listener;

    public UrlDownloader(DownloadListener listener, RequestType type) {
        this.type = type;
        this.listener = listener;
    }

    @Override
    protected HttpResponse doInBackground(String... params) {
        HttpClient httpClient = new DefaultHttpClient();
        HttpUriRequest request;
        HttpResponse response;

        if (type == RequestType.GET) {
            request = new HttpGet(params[0]);
        } else {
            request = new HttpPost(params[1]);
        }
        listener.setRequest(request);
        try {
             response = httpClient.execute(request);
        } catch (Exception e) {
            listener.onError(e);
            return null;
        }

        return response;
    }

    @Override
    protected void onPostExecute(HttpResponse response) {
        try {
            Log.d(TAG, response.getAllHeaders()[0].getValue() + "");
            listener.onRecive(EntityUtils.toString(response.getEntity()));
        } catch (Exception e) {
            listener.onError(e);
        }
    }

    public interface DownloadListener {
        public void onRecive(String content);
        public void onError(Exception e);
        public void setRequest(HttpRequest request);
    }

}

Answer 1

您需要使用onPostExecute来处理IsValid AsyncTask的结果。我不明白：为什么两个AsyncTasks？一个就足够了，在那里做所有事情，并且只用onPostExecute来处理结果。

doInBackground中发生的任何事情都在一个单独的线程中，onPostExecute再次发生在UI线程上。一个AsyncTask就足够了，但不能在validateToken方法中获取结果。在那里，只需执行AsyncTask以及您需要对onPostExecute中必须启动的结果执行的任何操作。

作为我的意思的一个基本例子：

public boolean validateToken(TokenAccess token) {
  new YourAsyncTask().execute(token);
  // DON'T rely on a result here
}

public class YourAsyncTask extends AsyncTask<?, ?, ?> {

  @Override
  protected ? doInBackground(?) {
    // do networking in background-task

    return result;
  }

  @Override
  protected void onPostExecute(? response) {
    // handle result here.. call a method in your main class, a listener with the result, or start an Activity directly
  }
}

Android UI，网络和异步代码

1 个答案: