web-dev-qa-db-ja.com

Androidアクティビティで非同期タスクを呼び出す

グリッドビューから画像を選択するアクティビティがあり、画像を保存できます。すべてのコードに非同期タスクを使用しています。 AsyncTaskをいくつかのクラスから分離しました。自分のアクティビティからそれらを呼び出すにはどうすればよいですか？文字列をAsyncTaskに戻すにはどうすればよいですか。

SingleImageView.class

@Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case R.id.save_image:
                new SaveImageTask().execute(image_url,context); //<-- The method execute(String...) in the type AsyncTask<String,String,String> is not applicable for the arguments (String, Context)

                  return true;
            default:
                return false;
        }

SaveImageTask.class

 public class SaveImageTask extends AsyncTask<String, String, String>
    {
        private Context context;
        private ProgressDialog pDialog;
        String image_url;
        URL myFileUrl = null;
        Bitmap bmImg = null;
        @Override
        protected void onPreExecute() {
            // TODO Auto-generated method stub

            super.onPreExecute();

            pDialog = new ProgressDialog(context);  //<<-- Couldnt Recognise
            pDialog.setMessage("Downloading Image ...");
            pDialog.setIndeterminate(false);
            pDialog.setCancelable(false);
            pDialog.show();

        }

        @Override
        protected String doInBackground(String... args) {
            // TODO Auto-generated method stub

            try {  
                myFileUrl = new URL(image_url);
                HttpURLConnection conn = (HttpURLConnection) myFileUrl.openConnection();   
                conn.setDoInput(true);   
                conn.connect();     
                InputStream is = conn.getInputStream();
                bmImg = BitmapFactory.decodeStream(is); 
            }
            catch (IOException e)
            {       
                e.printStackTrace();  
            }
            try {       

                String path = myFileUrl.getPath();
                String idStr = path.substring(path.lastIndexOf('/') + 1);
            File filepath = Environment.getExternalStorageDirectory();
            File dir = new File (filepath.getAbsolutePath() + "/Wallpaper/");
                dir.mkdirs();
                String fileName = idStr;
                File file = new File(dir, fileName);
                FileOutputStream fos = new FileOutputStream(file);
                bmImg.compress(CompressFormat.JPEG, 75, fos);   
                fos.flush();    
                fos.close();       
            }
            catch (Exception e)
                    {
                        e.printStackTrace();  
                    }
            return null;   
        }
        @Override
        protected void onPostExecute(String args) {
            // TODO Auto-generated method stub

            pDialog.dismiss();

        }
    }
androidclassandroid-activityandroid-asynctask
9
Android Novice

SaveImageTaskの新しいインスタンスを作成し、そのexecuteメソッドを呼び出して、String引数を渡します（executeは可変引数を取ります）。

new SaveImageTask().execute("foo", "bar");

編集

AsyncTaskはContextを使用するため、コンストラクターを介して渡す必要があります。

public class SaveImageTask extends AsyncTask<String, String, String>
{
    private Context context;
    private ProgressDialog pDialog;
    String image_url;
    URL myFileUrl = null;
    Bitmap bmImg = null;

    public SaveImageTask(Context context) {
        this.context = context;
    }

    ...

}

次に、次のようにAsyncTaskからActivityを呼び出します。

new SaveImageTask(this).execute("foo", "bar");
16
Tyler Treat
private PopupWindow popupWindow;
// this function will be on MainActivity class


 findViewById(R.id.main_page_layout).post(new Runnable() {
               public void run() {

                   new SendJsonValue ().execute();
                   }
                });

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

        @Override

        protected void onPreExecute(){
            /*code for pop window initialization begins here*/      
                LayoutInflater layoutInflater =(LayoutInflater) getBaseContext().getSystemService(LAYOUT_INFLATER_SERVICE);
                  final View popupView = layoutInflater.inflate(R.layout.popup_window, null);
                  popupWindow = new PopupWindow(
                         popupView, 
                         LayoutParams.FILL_PARENT,  
                               LayoutParams.FILL_PARENT);  //creating popup
                  popupWindow.showAtLocation(popupView, Gravity.CENTER, 0, 0);
        }

        protected String doInBackground(String... params) {
            // TODO Auto-generated method stub
            //loadingMore = true;//parameter to take control on load more
            HttpClient httpclient = new DefaultHttpClient();
            final HttpParams httpParams = httpclient.getParams();
            HttpConnectionParams.setConnectionTimeout(httpParams, 30000);//set time out for receiving response
            HttpConnectionParams.setSoTimeout(httpParams, 30000);
            HttpPost httppost = new HttpPost("http://10.0.2.2/upload_test/InsertData.php");  

            try{

                BasicNameValuePair idValuePair = new BasicNameValuePair("dev_id", device_id);
                BasicNameValuePair emailValuePair = new BasicNameValuePair("dev_email", device_email);
                BasicNameValuePair jsonStringValuePair = new BasicNameValuePair("json", jObjectMain.toString());

                List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
                nameValuePairs.add(idValuePair);
                nameValuePairs.add(emailValuePair);
                nameValuePairs.add(jsonStringValuePair);

                httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));


                HttpResponse response = httpclient.execute(httppost);  //response class to handle responses
                jsonResult = inputStreamToString(response.getEntity().getContent()).toString();

                JSONObject object = new JSONObject(jsonResult);



        }catch(ConnectTimeoutException e){

        }catch (ClientProtocolException e) {  
            // TODO Auto-generated catch block
            e.printStackTrace();
        }catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace(); 
        }catch (JSONException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }catch(Exception e){

        }

            return jsonResult;

    }
    protected void onPostExecute(String Result){


         System.out.println(Result);



        }
        private StringBuilder inputStreamToString(InputStream is) {
            String rLine = "";
            StringBuilder answer = new StringBuilder();
            BufferedReader rd = new BufferedReader(new InputStreamReader(is));

            try {
             while ((rLine = rd.readLine()) != null) {
              answer.append(rLine);
               }
            }

            catch (IOException e) {
                e.printStackTrace();
             }
            return answer;
           }  
    }
0
Anjan Debnath