Android的蜂窝：片段无法启动AsyncTask的？ [英] Android Honeycomb: Fragment not able to start AsyncTask?

问题描述

我碰到的<一个href="http://stackoverflow.com/questions/6277584/android-honeycomb-networkonmainthreadexception-even-when-using-asynctask-and-no">this错误过，但认为这是一些错误的严格模式系统。然而，这显然是正确的，因为我悲伤地发现了。 ：（

I've run into this error before, but thought it was some mistake by the strict mode system. However, it apparently was right as I sadly found out now. :(

我的PROGRAMM由一个活动和片段的负载。我有一个NetworkWorker片段，启动URL请求是这样的：

My programm is made of one Activity and loads of Fragments. I have a NetworkWorker fragment, which starts URL requests like this:

public void startURLRequest(Fragment target, String url, String message)
{

    if (asyncTask != null) asyncTask.cancel(true);
    asyncTask = new FragmentHttpHelper(url, message, target);
    asyncTask.doInBackground();

    return;
}

FragmentHttpHelper是AsyncTask的派生的自定义内部类：

FragmentHttpHelper is a custom inner class derived from AsyncTask:

private class FragmentHttpHelper extends AsyncTask<Void, Void, String>
{
    //...

    @Override
    protected String doInBackground(Void... params)
    {

        if (CheckInternet())
        {
            try
            {
                URL myURL = new URL(url);
                httpClient = new DefaultHttpClient();

                if (this.message == null)
                {
                    httpRequest = new HttpGet(myURL.toExternalForm());
                }
                else
                {
                    httpRequest = new HttpPost(myURL.toExternalForm());

                    HttpEntity myEntity = new StringEntity(message, "UTF-8");
                    ((HttpPost) httpRequest).setEntity(myEntity);
                }

                // and so on...
            }
            //catches
            finally
            {
                // auf jeden Fall Verbindung beenden
                if (httpRequest != null) httpRequest.abort();
                // if (httpClient != null) httpClient.close();
            }

        }
        else
        {
            showDialog(getString(R.string.net_notify_no_network), target);
        }

        //...
    }

    /**
     * gets called after AsyncTask has finished
     */
    protected void onPostExecute(String result)
    {

        if (target == null)
        {
            ((NetworkWorkerListener) getActivity()).onDownloadHasFinished((!result.contentEquals(ERROR)), result);
        }
        else
        {
            ((NetworkWorkerListener) target).onDownloadHasFinished((!result.contentEquals(ERROR)), result);
        }
    }

}

NetworkWorkerListener只是对赖以起家的URL请求的片段回调的接口。这个类一直工作正常，当我在2.2的应用程序中使用它。我会得到它在我的活动呢。

NetworkWorkerListener is just an interface for a callback on the Fragment which started the URL request. This class has always worked fine when I used it in my 2.2 app. I would derive it in my Activities then.

现在，如果一个菜单项被选中，另一名工人片段开始通过上述方法的URL请求，并打开一个装载对话框：

Now, if a menu item is selected, another worker Fragment starts the URL request via the above method and opens a loading dialog:

FragmentManager fragmentManager = getFragmentManager();

NetworkWorker network = (NetworkWorker) fragmentManager.findFragmentByTag(TabletMain.NETWORK);
if (network == null) return WorkerFeedback.NO_NETWORK_WORKER;

myDialog = LoadingDialog.createInstance(getString(R.string.notify_download), this);
myDialog.show(fragmentManager, TabletMain.ONETIME);

network.startURLRequest(this, someurl, null);

目前至少这是应该发生的。 相反，当我点击菜单项，我的应用程序冻结，并显示没有加载对话框到。接下来发生的反应，下载结束（或者，在我的情况的错误消息，因为我发废话字符串）。含义onPostExecute（）为止。

At least that's what supposed to happen. Instead, when I click the menu item, my app freezes and no loading dialog is shown until. Next happening is the reaction to the end of the download (or, in my case an error message, as I am sending nonsense strings). Meaning onPostExecute() was reached.

我现在感觉真的坚持 - 是不是可以使用的AsyncTask与片段？还是我做错什么了？

I feel really stuck now - is it not possible to use AsyncTask with Fragments? Or did I do something wrong?

感谢您的帮助， 水母

推荐答案

不要叫 doInBackground 直接调用执行，而不是（在异步任务）

Don't call doInBackground directly, call execute instead (on the async task)

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