android - 我正在使用 gridview，其中我在 android 中解析来自 json 的数据，但有时我的应用程序运行并且有时会拒绝执行 eception

Question

public class TopMovie extends Activity 
{

    GridView lv;

    Vibrator vibrator;
    private Object params;
    public static String movie_Id;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        Log.i("Category", MainActivity.movie_Category);
        setContentView(R.layout.new_movie);
        LayoutInflater inflater = getLayoutInflater();
        View view = inflater.inflate(R.layout.customtoast,
                (ViewGroup) findViewById(R.id.custom_toast_layout));
        Toast toast = new Toast(getApplicationContext());
        toast.setDuration(Toast.LENGTH_LONG);
        toast.setGravity(Gravity.CENTER_HORIZONTAL, 0, 0);
        toast.setView(view);
        toast.show();

        vibrator = (Vibrator) getSystemService(Context.VIBRATOR_SERVICE);
        lv = (GridView) findViewById(R.id.grid_view);

        // URL to the JSON data
        String strUrl = "http://vaibhavtech.com/work/android/movie_list.php?category="
                + MainActivity.movie_Category + "&sub_category=other";
        DownloadTask downloadTask = new DownloadTask();
        downloadTask.execute(strUrl);
        lv.setOnItemClickListener(new OnItemClickListener() {

            @Override
            public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
                    long arg3) {
                // // TODO Auto-generated method stub
                vibrator.vibrate(40);
                LayoutInflater inflater = getLayoutInflater();
                View view = inflater.inflate(R.layout.customtoast,
                        (ViewGroup) findViewById(R.id.custom_toast_layout));
                Toast toast = new Toast(getApplicationContext());
                toast.setDuration(Toast.LENGTH_LONG);
                toast.setGravity(Gravity.CENTER_HORIZONTAL, 0, 0);
                toast.setView(view);
                toast.show();
                MainActivity.movie_Id = ((TextView) arg1
                        .findViewById(R.id.tv_girdview_content_id)).getText()
                        .toString();
                Log.i("Name is", MainActivity.movie_Id);
                startActivity(new Intent(TopMovie.this, MovieDescription.class));
            }
        });
    }

    private String downloadUrl(String strUrl) throws IOException {
        String data = "";
        InputStream iStream = null;
        try {
            URL url = new URL(strUrl);

            // Creating an http connection to communicate with url
            HttpURLConnection urlConnection = (HttpURLConnection) url
                    .openConnection();

            // Connecting to url
            urlConnection.connect();

            // Reading data from url
            iStream = urlConnection.getInputStream();

            BufferedReader br = new BufferedReader(new InputStreamReader(
                    iStream));

            StringBuffer sb = new StringBuffer();

            String line = "";
            while ((line = br.readLine()) != null) {
                sb.append(line);
            }

            data = sb.toString();

            br.close();

        } catch (Exception e) {
            Log.d("Exception while downloading url", e.toString());
        } finally {
            iStream.close();
        }

        return data;
    }

    /** AsyncTask to download json data */
    private class DownloadTask extends AsyncTask<String, Integer, String> {
        String data = null;

        @Override
        protected String doInBackground(String... url) {
            try {
                data = downloadUrl(url[0]);

            } catch (Exception e) {
                Log.d("Background Task", e.toString());
            }
            return data;
        }

        @Override
        protected void onPostExecute(String result) {

            // The parsing of the xml data is done in a non-ui thread
            ListViewLoaderTask listViewLoaderTask = new ListViewLoaderTask();

            // Start parsing xml data
            listViewLoaderTask.execute(result);

        }
    }

    /** AsyncTask to parse json data and load ListView */
    private class ListViewLoaderTask extends
            AsyncTask<String, Void, SimpleAdapter> {

        JSONObject jObject;

        // Doing the parsing of xml data in a non-ui thread
        @Override
        protected SimpleAdapter doInBackground(String... strJson) {
            try {
                jObject = new JSONObject(strJson[0]);
                MovieParser countryJsonParser = new MovieParser();
                countryJsonParser.parse(jObject);
            } catch (Exception e) {
                Log.d("JSON Exception1", e.toString());
            }

            // Instantiating json parser class
            MovieParser countryJsonParser = new MovieParser();

            // A list object to store the parsed countries list
            List<HashMap<String, Object>> countries = null;

            try {
                // Getting the parsed data as a List construct
                countries = countryJsonParser.parse(jObject);
            } catch (Exception e) {
                Log.d("Exception", e.toString());
            }

            // Keys used in Hashmap
            String[] from = { "image", "id", "year", "duration", "name" };

            // Ids of views in listview_layout
            // int[] to = {
            // R.id.iv_radio_data_image,R.id.tv_radio_data_id,R.id.tv_radio_data_like,R.id.tv_radio_data_rating,R.id.tv_radio_data_listner,R.id.tv_radio_data_radio_url,R.id.tv_radio_data_name};
            int[] to = { R.id.iv_girdview_content_image,
                    R.id.tv_girdview_content_id, R.id.tv_girdview_content_like,
                    R.id.tv_girdview_content_listner,
                    R.id.tv_girdview_content_name };

            SimpleAdapter adapter = new SimpleAdapter(getBaseContext(),
                    countries, R.layout.grid_view_content, from, to);

            return adapter;
        }

        /** Invoked by the Android on "doInBackground" is executed */
        @Override
        protected void onPostExecute(SimpleAdapter adapter) {

            // Setting adapter for the listview
            lv.setAdapter(adapter);

            for (int i = 0; i < adapter.getCount(); i++) {
                HashMap<String, Object> hm = (HashMap<String, Object>) adapter
                        .getItem(i);
                String imgUrl = (String) hm.get("flag_path");
                ImageLoaderTask imageLoaderTask = new ImageLoaderTask();

                HashMap<String, Object> hmDownload = new HashMap<String, Object>();
                hm.put("flag_path", imgUrl);
                hm.put("position", i);

                // Starting ImageLoaderTask to download and populate image in
                // the listview
                imageLoaderTask.execute(hm);
            }

        }
    }

    /** AsyncTask to download and load an image in ListView */
    private class ImageLoaderTask extends
            AsyncTask<HashMap<String, Object>, Void, HashMap<String, Object>> {

        @Override
        protected HashMap<String, Object> doInBackground(
                HashMap<String, Object>... hm) {

            InputStream iStream = null;
            String imgUrl = (String) hm[0].get("flag_path");
            int position = (Integer) hm[0].get("position");

            URL url;
            try {
                url = new URL(imgUrl);

                // Creating an http connection to communicate with url
                HttpURLConnection urlConnection = (HttpURLConnection) url
                        .openConnection();

                // Connecting to url
                urlConnection.connect();

                // Reading data from url
                iStream = urlConnection.getInputStream();

                // Getting Caching directory
                File cacheDirectory = getBaseContext().getCacheDir();

                // Temporary file to store the downloaded image
                File tmpFile = new File(cacheDirectory.getPath() + "/wpta_"
                        + position + ".png");

                // The FileOutputStream to the temporary file
                FileOutputStream fOutStream = new FileOutputStream(tmpFile);

                // Creating a bitmap from the downloaded inputstream
                Bitmap b = BitmapFactory.decodeStream(iStream);

                // Writing the bitmap to the temporary file as png file
                b.compress(Bitmap.CompressFormat.PNG, 100, fOutStream);

                // Flush the FileOutputStream
                fOutStream.flush();

                // Close the FileOutputStream
                fOutStream.close();

                // Create a hashmap object to store image path and its position
                // in the listview
                HashMap<String, Object> hmBitmap = new HashMap<String, Object>();

                // Storing the path to the temporary image file
                hmBitmap.put("image", tmpFile.getPath());

                // Storing the position of the image in the listview
                hmBitmap.put("position", position);

                // Returning the HashMap object containing the image path and
                // position
                return hmBitmap;
            } catch (Exception e) {
                e.printStackTrace();
            }
            return null;
        }

        @Override
        protected void onPostExecute(HashMap<String, Object> result) {
            // Getting the path to the downloaded image
            String path = (String) result.get("image");

            // Getting the position of the downloaded image
            int position = (Integer) result.get("position");

            // Getting adapter of the listview
            SimpleAdapter adapter = (SimpleAdapter) lv.getAdapter();

            // Getting the hashmap object at the specified position of the
            // listview
            HashMap<String, Object> hm = (HashMap<String, Object>) adapter
                    .getItem(position);

            // Overwriting the existing path in the adapter
            hm.put("image", path);
            adapter.notifyDataSetChanged();
        }

    }

}

我的应用程序正在调试但未运行。RejectedExecutionException:任务 android.os.AsyncTas 被 java.util.concurrent 拒绝。 Submitting tasks to a thread-pool gives RejectedExecutionExceptiongridview android 中如何解决线程池异常

Answer 1

您可以更改 executor asynctask在扩展 asynctask 类时使用。

检查 this example从他们下载多个图像并使用自定义异步任务来控制并发性的文档。

我遇到了你遇到的同样问题，并使用该项目来修复它。