java - 如何解决 InputEventReceiver 错误？

Question

我在 android 中创建了一个小程序来同步来自云端的数据，但是每当我按下刷新按钮(用于开发目的)时，代码都没有响应。Logcat 显示:

02-25 22:57:32.195: W/InputEventReceiver(17762): Attempted to finish an input event but the input event receiver has already been disposed.

The java code for the MainActivity and the FragmentActivity classes are given below

package sunshine.com.example.himanshu.sunshine;

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v7.app.ActionBarActivity;
import android.view.Menu;
import android.view.MenuItem;


public class MainActivity extends ActionBarActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        if (savedInstanceState == null) {
           getSupportFragmentManager().beginTransaction().add(R.id.container, new ForecastFragment()).commit();       }
    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }

}

包 sunshine.com.example.himanshu.sunshine;

import android.annotation.TargetApi;


import android.net.Uri;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ListView;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Date;
import java.util.List;

/**
 * Created by Himanshu on 2/25/2015.
 */

public class ForecastFragment extends Fragment
{
    public ForecastFragment() {
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setHasOptionsMenu(true);
    }

    @Override
    public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
        inflater.inflate(R.menu.forecast_fragment,menu);

    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        int id=item.getItemId();

        if(id==R.id.refresh_action)
        {
            FetchWeatherTask fetch=new FetchWeatherTask();
            fetch.execute("716217");
            return true;
        }
        return super.onOptionsItemSelected(item);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_main, container, false);
        String forecastArray[] =
           {    "Today-sunny-23/34",
                "Tomorrow-foggy-45/67",
                "Wed-asteroid-54/34",
                "Thursday--sunny-34/56",
                "Fri-foggy-45/34"
                , "Sat-day-23/45"
                , "Sun-Sunny-34/65",
                "Someday-gloomy-78/90",
                "Sat-day-23/45",
                "Wed-asteroid-54/34",
                "Today-sunny-23/34"        };
        List<String> weekForecast = new ArrayList<String>(Arrays.asList(forecastArray));
        ArrayAdapter<String> mForecastAdapter = new ArrayAdapter<String>(getActivity(), R.layout.list_item_forecast, R.id.list_item_forecast_textview, weekForecast);
        ListView listView = (ListView) rootView.findViewById(R.id.listview_forecast);
        listView.setAdapter(mForecastAdapter);


        return rootView;
    }

    public class FetchWeatherTask extends AsyncTask<String, Void, Void> {

        private final String LOG_TAG = FetchWeatherTask.class.getSimpleName();

        @Override
        protected Void doInBackground(String... params)
        {
            if(params.length==0)
                return null;

            // 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;

            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 format="json";
                String unit="metric";
                int days=7;
                final String surl="http://api.openweathermap.org/data/2.5/forecast/daily?";
                final String pcode="q";
                final String mode="mode";
                final String units="units";
                final String daysy="cnt";
                Uri urlbulilt=Uri.parse(surl).buildUpon().appendQueryParameter(pcode,params[0])
                        .appendQueryParameter(mode,format)
                        .appendQueryParameter(units,unit)
                        .appendQueryParameter(daysy,Integer.toString(days)).build();
                URL url=new URL(urlbulilt.toString());



                // 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) {
                    // Nothing to do.
                    return null;
                }
                reader = new BufferedReader(new InputStreamReader(inputStream));

                String line;
                while ((line = reader.readLine()) != null) {
                    // Since it's JSON, adding a newline isn't necessary (it won't affect parsing)
                    // But it does make debugging a *lot* easier if you print out the completed
                    // buffer for debugging.
                    buffer.append(line + "\n");
                }

                if (buffer.length() == 0) {
                    // Stream was empty.  No point in parsing.
                    return null;
                }
                forecastJsonStr = buffer.toString();
            } catch (IOException e) {
                Log.e(LOG_TAG, "Error ", e);
                // If the code didn't successfully get the weather data, there's no point in attemping
                // to parse it.
                return null;
            } finally {
                if (urlConnection != null) {
                    urlConnection.disconnect();
                }
                if (reader != null) {
                    try {
                        reader.close();
                    } catch (final IOException e) {
                        Log.e(LOG_TAG, "Error closing stream", e);
                    }
                }
            }
            return null;
        }
    }
}

Answer 1

我认为这是因为您的 fetch 对象是 onOptionsItemSelected() 方法的局部变量，在 AsyncTask 完成时它已经被垃圾回收了。

尝试将其设为字段，然后在 onOptionsItemSelected() 方法中分配

public class ForecastFragment extends Fragment {

    private FetchWeatherTask fetch;

    public ForecastFragment() {
    }

...

然后

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    int id=item.getItemId();

    if(id==R.id.refresh_action)
    {
        fetch=new FetchWeatherTask();
        fetch.execute("716217");
        return true;
    }
    return super.onOptionsItemSelected(item);
}

现在，当 AsyncTask 完成时，您的提取对象应该仍然存在。