Android Asynctask：应用程序可能在其主线程上做了太多工作

Question

我的代码可以工作，但我在监视器中有一条异常消息：我/编舞：跳过了37帧！应用程序可能在其主线程上做了太多工作。

我知道这个错误消息意味着我在用户界面线程中做了很多繁重的处理。问题是对我来说，除了向列表视图添加假数据，我在用户界面线程上几乎什么都不做。我正在使用Asyncask发出一个应用编程接口请求，这是我正在做的唯一的“繁重”工作，它不在主线程中。

我把我所有的代码放在这里，但我认为大部分都不是问题，因为当我注释我所有的假数据代码和调用我的Asyncask时，我仍然有这个问题。所以我想问题更多的是我如何使用这个片段，因为我从来没有使用过，所以我肯定在任何地方都犯了一个错误...

//==== list_item_forecast.xml
<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:minHeight="?android:attr/listPreferredItemHeight"
    android:gravity="center_vertical"
    android:id="@+id/list_item_forecast_textview" />

//====fragment_main.xml
<?xml version="1.0" encoding="utf-8"?>
<!-- using a FrameLayout because only one child element -->
<FrameLayout     xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent">
    <ListView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/listview_forecast"/>
</FrameLayout>

//==== content_main.xml
<fragment     xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/fragment"
    android:name="com.example.android.sunshine.app.MainActivityFragment"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:layout="@layout/fragment_main" />


//==== MainActivity
public class MainActivity extends AppCompatActivity implements ForecastRequest {

    private static String appId = "";
    // Will contain the raw JSON response as a string.
    String forecastJsonStr = null;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        // Get OpenWeather API key
        appId = getResources().getString(R.string.APPID);

        try {
            // Construct the URL for the OpenWeatherMap query
            // Possible parameters are avaiable at OWM's forecast     API page, at
        // http://openweathermap.org/API#forecast
            String url =     "http://api.openweathermap.org/data/2.5/forecast/daily?    q=94043&mode=json&units=metric&cnt=7&APPID=" + appId;
            OpenWeatherRequest request = new OpenWeatherRequest();
            request.response = this;
            request.execute(url);

        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    @Override
    public void requestDone(String jsonResponse) {
        forecastJsonStr = jsonResponse;
        Log.d(Constants.LOG_TAG,forecastJsonStr);
    }
}

//==== Interface used to get result from AsyncTask in MainActivity
public interface ForecastRequest {
    void requestDone(String output);
}

//==== The AsyncTask that make a request to OpenWeather API
public class OpenWeatherRequest extends AsyncTask<String, Integer, String> {
    // These two need to be declared outside the try/catch
    // so that they can be closed in the finally block.
    HttpURLConnection urlConnection = null;
    BufferedReader reader = null;
    // Will contain the raw JSON response as a string.
    String forecastJsonStr = null;
    public ForecastRequest response = null;

    protected void onPreExecute() {
        Log.d(Constants.LOG_TAG,"Fetching data...");
    }

    protected String doInBackground(String... urls) {
        try {
            URL url = new URL(urls[0]);

            // Create the request to OpenWeatherMap, and open the connection
            urlConnection = (HttpURLConnection) url.openConnection();
            urlConnection.setRequestMethod("GET");
            urlConnection.connect();

            // Read the input stream into a String
            InputStream inputStream =     urlConnection.getInputStream();
            StringBuffer buffer = new StringBuffer();
            if (inputStream == null) {
                throw new Exception("No data");
            }
            reader = new BufferedReader(new InputStreamReader(inputStream));

            String line;
            while ((line = reader.readLine()) != null) {
                buffer.append(line + "\n");
            }

            if (buffer.length() == 0) {
                return null;
            }
            forecastJsonStr = buffer.toString();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return forecastJsonStr;
    }

    protected void onPostExecute(String result) {
        response.requestDone(result);
    }
}

//==== The fragment
public class MainActivityFragment extends Fragment {

    private ArrayAdapter<String> mForecastAdapter;
    ArrayList<String> weekForecast;
    private ListView mListView;


    public MainActivityFragment() {

    }

    public void onViewCreated(View view, Bundle savedInstanceState) {


    }

    public View onCreateView(LayoutInflater inflater, ViewGroup     container,
                             Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_main,     container, false);

        //=== Add fake data
        weekForecast = new ArrayList<>(Arrays.asList(
                "Today - Sunny - 88/63",
                "Tomorrow - Foggy - 70/40",
                "Weds - Cloudy - 72/63",
                "Thurs - Asteroids - 75/65",
                "Fri - Heavy Rain - 65/56",
                "Sat - HELP TRAPPED IN WEATHERSTATION - 60/51",
                "Sun - Sunny - 80/68")
        );

        mForecastAdapter = new ArrayAdapter<>(
                // The current context (this fragment parent activity)
                getActivity(),
                // ID of list item layout
                R.layout.list_item_forecast,
                // ID of the textview to populate
                R.id.list_item_forecast_textview,
                // Data
                weekForecast);

        mListView =     (ListView)rootView.findViewById(R.id.listview_forecast);
        mListView.setAdapter(mForecastAdapter);

        return rootView;
    }
}

Answer 1

我只是在手机上试了一下，没有在Android Studio模拟器上试过，消息就消失了。所以问题来自模拟器，而不是我的代码。