如何在Android中實現ASyncTask

任何人都可以告訴我如何使用ASyncTask更新UI並舉例說明嗎？如何在Android中實現ASyncTask

我從兩個webservices獲取價值。從兩個webservices我得到的價值在兩個arraylist上後期方法將不會返回值它將循環四捨五入。我如何從onPostExecuteMethod返回？

這是我的異步類：

public class HomeTask extends AsyncTask<Void,Void,Bundle> 
{ 

     private Context ctx; 
     public HomeTask(Context context) { 
      ctx = context; 
     } 

     @Override 
     protected void onPreExecute() { 
      //super.onPreExecute(); 
     //setContentView(R.layout.splash); 

      dlg = new ProgressDialog(getDialogContext()); 
      dlg.setMessage("Loading...."); 
      dlg.show(); 
      //setContentView(R.layout.splash); 
     } 


     @Override 
     protected Bundle doInBackground(Void... params) { 
       Bundle b=new Bundle(); 

      // TODO Auto-generated method stub 
      try 
      { 


        WebService tableservice=new WebService(); 
       tableservicevalue=tableservice.callTableServer(SOAP_ACTION,"",strUsername,strPassWord,questGroupId,URL); 
        tableservicevalue=decodeXMLData(tableservicevalue); 

        DomTableParser parser=new DomTableParser(); 
       parser.setTableservicevalue(tableservicevalue); 
       parsedValue=parser.parseXmlFile(tableservicevalue); 
       Log.d("1234%%%%$$$$$$$parsed value$$$$$", parsedValue.toString()); 
        WebService service=new WebService(); 
        webservicevalue=service.callHomeServer(SOAP_ACTION,"",strUsername,strPassWord,questGroupId,URL); 
        webservicevalue=decodeXMLData(webservicevalue); 
        ArticleParser articleParser=new ArticleParser(); 
       articleParsedValue=articleParser.parseXmlArticle(webservicevalue); 

       //b.putStringArrayList("articleParsedValue", articleParsedValue); 

       Log.d("(((((((parsed value is",parsedValue.toString()); 

       b.putStringArrayList("parsedValue", parsedValue); 
       b.putStringArrayList("articleParsedValue", articleParsedValue); 
       Log.d("(((((((parsed value is",articleParsedValue.toString()); 



      } 
      catch (Exception e) { 
      // TODO: handle exception 
       e.printStackTrace(); 
     } 

     return b; 
     }     
      @Override 
      protected void onPostExecute(Bundle b) { 


       Log.d("vijay checking","checking&&&&"); 
           Log.d("****","*********"); 
           Log.d("calling","handler"); 
           Log.d("****","*********"); 


       parsedValue1=b.getStringArrayList("parsedValue"); 
       articleParsedValue1=b.getStringArrayList("articleParsedValue");     

}

onupdating用戶界面

new HomeTask(HomeActivity2.this).execute(null); 

for(int i=0;i<parsedValue1.size();i++) 
{ 
       DomParserTableDataSet dataSet=(DomParserTableDataSet)parsedValue1.get(i); 

       if(i==0) 
       { 
        Log.d("&&&&&&index name is", dataSet.getIndexName()); 
        Log.d("&&&&&&index name is", dataSet.getLastValue()); 
        Log.d("&&&&&&index name is",dataSet.getChangePercentage()); 
       txtindex0.setText(dataSet.getIndexName()); 
       txtlast0.setText(dataSet.getLastValue()); 
       txtchange0.setText(dataSet.getChangePercentage()); 
       } 
       if(i==1) 
       { 
        Log.d("&&&&&&index name is", dataSet.getIndexName()); 
        Log.d("&&&&&&index name is", dataSet.getLastValue()); 
        Log.d("&&&&&&index name is",dataSet.getChangePercentage()); 
        txtindex1.setText(dataSet.getIndexName()); 
        txtlast1.setText(dataSet.getLastValue()); 
        txtchange1.setText(dataSet.getChangePercentage()); 
       } 
       if(i==2) 
       { 
       Log.d("&&&&&&index name is", dataSet.getIndexName()); 
       Log.d("&&&&&&index name is", dataSet.getLastValue()); 
       Log.d("&&&&&&index name is",dataSet.getChangePercentage()); 
       txtindex2.setText(dataSet.getIndexName()); 
       txtlast2.setText(dataSet.getLastValue()); 
       txtchange2.setText(dataSet.getChangePercentage()); 
       } 

      if(i==3) 
      { 
       Log.d("&&&&&&index name is", dataSet.getIndexName()); 
       Log.d("&&&&&&index name is", dataSet.getLastValue()); 
       Log.d("&&&&&&index name is",dataSet.getChangePercentage()); 
      txtindex3.setText(dataSet.getIndexName()); 
       txtlast3.setText(dataSet.getLastValue()); 
       txtchange3.setText(dataSet.getChangePercentage()); 
      } 

      } 


     // 
     for(int i=0;i<articleParsedValue1.size();i++) 
     { 

      System.out.println("for loop checking i is"+i); 
       ArticleDataSet articleDataset=(ArticleDataSet)articleParsedValue1.get(i); 

      System.out.println("articleDataset.getArticle_title()"+articleDataset.getArticle_title());  

       HashMap<String, String> mapValue=new HashMap<String, String>(); 
        WebView webviewcontent=new WebView(HomeActivity2.this); 
      if(articleDataset.getArticle_summary().length()>75) 
      { 
        summary=articleDataset.getArticle_summary().substring(0,75)+"..."; 
      } 
      else 
      { 
       summary=articleDataset.getArticle_summary(); 
      } 


       String html ="<html><body><div><label> <font face=\"verdana\" color=\"#C1002B\" size=\"4\"><b>"+articleDataset.getArticle_title()+"</b> </font> </label>"+ "<label> <font color=\"#000000\" size=\"2\" face=\"verdana\">"+"|"+"</font></label> "+"<label> <font color=\"#AAAAAA\" face=\"verdana\" size=\"2\">"+articleDataset.getArticle_date()+" </font></label></div>"; 
      html=html+"<div><label> <font color=\"#000000\" face=\"verdana\" size=\"2\">"+summary+" </font></label></div></body></html>" ; 
      webviewcontent.getSettings().setJavaScriptEnabled(true); 
      webviewcontent.clearCache(true); 
      final Activity activity = HomeActivity2.this; 


      webviewcontent.loadData(html, "text/html", "utf-8"); 

      if(i==articleParsedValue1.size()-1) 
         { 
      webviewcontent.setWebViewClient(new WebViewClient() 
      { 
       public boolean shouldOverrideUrlLoading(WebView view, String url) 
       {    
        view.loadUrl(url); 
        return true;   
       } 

       public void onPageFinished(WebView view, String url) 
       { 

       // setContentView(R.layout.home); 

       if (dlg.isShowing()) 
        { 

        dlg.dismiss(); 
        dlg = null; 


        } 
       splash.setVisibility(View.GONE); 

       // setContentView(repl); 


       }     
      }); 
      } 
      mainlinear4.addView(webviewcontent); 
      //webviewcontent.setOnTouchListener(HomeActivity2.this);     

     } 

}

來源

2011-01-25 mohan

我真的不知道問題是什麼，你正在經歷。也許你可以解釋一下你有更清楚的問題？ – 2011-01-25 11:42:52

List<String> data; // declare here so that we can use it in onPostExecute(). 
public class YourActivity extends Activity { 
public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
    starttask(); 
} 
private void starttask() { 
     new FileAsync().execute("start"); 
     Toast toast = Toast.makeText(yourActivity.this," start:" , 7);toast.show(); 
    } 

class FileAsync extends AsyncTask<String, String, String> { 

     @Override 
     protected void onPreExecute() { 
      super.onPreExecute(); 
      m_ProgressDialog = ProgressDialog.show(yourActivity.this,  
        "", "Loading ...", true); 
     } 

     @Override 
     protected String doInBackground(String... aurl) { 

       // These methods are calling data from web service made 
       // in sperate class but you can do this here as well. 

     TempDAO tempDAO = new TempDAOImpl();       
     data = tempDAO.getDataList(arg1,arg2); 

      return null; 

     } 
     protected void onProgressUpdate(String... progress) { 
      Log.d("ANDRO_ASYNC",progress[0]); 

     } 

     @Override 
     protected void onPostExecute(String unused) { 
      TextView textData= new TextView(YourActivity.this); 
     textData.setText(data.get(1)); 
     textData.setTextColor(Color.WHITE); 
     textData.setGravity(Gravity.CENTER); 
     setContentView(textData); 
     m_ProgressDialog.dismiss(); 
     } 
    }

來源

2011-12-14 11:26:22

private class HttpAsyncTask extends AsyncTask<String, Void, String> { 
     AlertDialog.Builder builder; 

    protected void onPreExecute() { 
     super.onPreExecute(); 
     builder = new AlertDialog.Builder(TabGroup2ProductsActivity.this); 
    } 

    @Override 
    protected String doInBackground(String... urls) { 
     if (urls.length == 1) { 
      return POST(urls[0]); 
     } else { 
      if ("pdf".equalsIgnoreCase(urls[1])) { 
       downloadPDF(urls[0]); 
       return ""; 
      } else { 
       downloadImage(urls[0]); 
       return ""; 
      } 
     } 
    } 

    @Override 
    protected void onPostExecute(String result) { 
    } 
} 

public String POST(String url) { 
    System.out.println("I am in post data./.............................."); 
    HttpClient httpclient = new DefaultHttpClient(); 
    HttpGet httppost = new HttpGet(url); 
    String result = null; 
    try { 
     HttpResponse response = httpclient.execute(httppost); 
     int status = response.getStatusLine().getStatusCode(); 
     System.out.println("Status is : " + status); 
     ParseProductJson parseJson = new ParseProductJson(); 
     if (status == 200) { 
      result = EntityUtils.toString(response.getEntity()); 
      System.out 
        .println("################result1###############################" 
          + result); 
      FileOutputStream fos = openFileOutput("productsJson.json", 
        Context.MODE_PRIVATE); 
      fos.write(result.getBytes()); 
      fos.close(); 
      System.out.println("Done"); 
      HashMap<String, List<Product>> hashmap = parseJson 
        .parseProductJson(readProductsJSON("productsJson.json")); 
      arrGroupelements = parseJson.getHeadingArray(hashmap); 
      arrChildelements = parseJson.get2dArray(hashmap); 
      statusClass = status; 
     } else { 
      statusClass = 400; 
      result = "Did not work!"; 
     } 
    } catch (ClientProtocolException e) { 
     e.printStackTrace(); 
    } catch (IOException e) { 
     e.printStackTrace(); 
    } 
    return result; 
} 
} 



and from Activity onCreate(){ 
int statusClass = 2; 

new HttpAsyncTask() 
        .execute("http://104.130.240.26:8080/bhn/service/products/"); 

do { 
       try { 
        Thread.sleep(2000); 
       } catch (InterruptedException e) { 
        e.printStackTrace(); 
       } 
      } while (statusClass == 2);     
}

樣品異步任務請求的web服務

來源

2015-02-06 06:47:12 user1728578

以下是怎樣的方式，使AsyncTask：

private class AsyncTaskGetPlaces extends AsyncTask<Void, Void, AsyncTaskResult<Object>> 
    { 
     @Override 
     protected void onPreExecute() { 
      super.onPreExecute(); 
     } 

     @Override 
     protected AsyncTaskResult<Object> doInBackground(Void... params) 
     { 
      try 
      { 
       LibHttp libHttp = new LibHttp(); 

       String res = libHttp.listBusiness("21","[email protected]"); 

       return new AsyncTaskResult<Object>(res); 
      } 
      catch (Exception e) 
      { 
       e.printStackTrace(); 

       return new AsyncTaskResult<Object>(e); 
      } 
     } 

     @Override 
     protected void onPostExecute(AsyncTaskResult<Object> result) 
     { 

      if(result.getError()!= null) 
      { 
       showOKAlertMsg("App",getResources().getString(R.string.txt_data_not_found), false); 
      } 
      else 
      { 
       String res = result.getResult().toString(); 

       try { 
        JSONObject resObj = new JSONObject(res); 

        if(resObj.getString("status_code").equals("1")){ 
         //parse 
         // Do your task here 

        } 

       } catch (JSONException e) { 
        e.printStackTrace(); 
        showOKAlertMsg("",getResources().getString(R.string.txt_internal_server_error), false); 
       } 
      } 
     } 
    }

哪裏AsyncTaskResult是

public class AsyncTaskResult<T> 
{ 
    private T result; 

    private Exception error; 

    public T getResult() 
    { 
     return result; 
    } 

    public Exception getError() 
    { 
     return error; 
    } 

    public AsyncTaskResult(T result) 
    { 
     this.result = result; 
    } 

    public AsyncTaskResult(Exception error) 
    { 
     this.error = error; 
    } 
}

來源

2016-03-16 06:55:10

如何在Android中實現ASyncTask

回答

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