不知道是否可以安全地實現這樣的Asynctask

我在android上做了一個代碼，我想從stackoverflow的人收到一些意見。它是關於我所用的AsyncTask類代碼...但我不知道它是否被編碼好還是不好......不知道是否可以安全地實現這樣的Asynctask

這是代碼：

package com.example.basicmaponline; 

import java.sql.ResultSet; 
import java.sql.SQLException; 
import java.sql.Statement; 
import java.util.HashMap; 
import java.util.concurrent.ExecutionException; 

import android.app.Activity; 
import android.content.Intent; 
import android.os.AsyncTask; 
import android.os.Bundle; 
import android.os.Handler; 
import android.os.Message; 
import android.util.Log; 

import com.mlab.android.basicoverlays.PostgreSQL; 
import com.mlab.android.basicoverlays.SQLloja; 

public class Intro extends Activity{ 

//SQLlistLoja listaLoja; 
HashMap<String, SQLloja> listaLoja; 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    // TODO Auto-generated method stub 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.intro); 
    //Intent openMainActivity = new Intent("com.example.basicmaponline.MAINACTIVITY"); //isto vem do ficheiro AndroidManifest.xml o "com.example....." 
    //startActivity(openMainActivity); 

    try { 
     listaLoja = new loadDatabase().execute().get(); 
    } catch (InterruptedException e1) { 
     // TODO Auto-generated catch block 
     e1.printStackTrace(); 
    } catch (ExecutionException e) {   
     // TODO Auto-generated catch block 
     e.printStackTrace(); 
    } 

    if(listaLoja !=null){ 
     for(SQLloja loja : listaLoja.values()){ 
      Log.d("ASYNC25", loja.getNome()); 
     } 
    } 
    else{ 
     Log.d("ASYNC25", "NAO GUARDOU!"); 
    } 

    Thread timer = new Thread(){ 
     public void run(){ 
      try{ 
       sleep(3000); 
      }catch (InterruptedException e) { 
       // TODO: handle exception 
       e.printStackTrace(); 
      }finally{ 
       Intent openMenu = new Intent("com.example.basicmaponline.MENU"); //isto vem do ficheiro AndroidManifest.xml o "com.example....." 
       openMenu.putExtra("listaLoja",listaLoja); 
       startActivity(openMenu); 
      } 
     } 
    }; 
    timer.start(); 
} 

@Override 
protected void onPause() { 
    // TODO Auto-generated method stub 
    super.onPause(); 
    //ourSong.release(); //release the music and we are done with you 
    finish(); 
} 

//@SuppressWarnings("rawtypes") 
public class loadDatabase extends AsyncTask<Void, Void, HashMap<String,SQLloja>>{ 

    @Override 
    protected HashMap<String,SQLloja> doInBackground(Void... params) { 
     // TODO Auto-generated method stub 

     HashMap<String,SQLloja>listaLojas = new HashMap<String, SQLloja>(); 
    try{  
     PostgreSQL pSQL = new PostgreSQL(host,db, username, password); 
     String sql = pSQL.getLojasCidadao(); 
     Statement st = pSQL.getConnection().createStatement(); 
     ResultSet rs = st.executeQuery(sql); 

     Log.d("ASYNC2","Entrei na thread ASYNCTASK"); 

     while(rs.next()){ 
      int lcId = Integer.parseInt(rs.getString(1)); 
      String lcNome=rs.getString(2); 
      String lcCP = rs.getString(3); 
      int lcDistrito = Integer.parseInt(rs.getString(4)); 
      int lcConselho = Integer.parseInt(rs.getString(5)); 
      double lcAltitude = Double.parseDouble(rs.getString(6)); 
      double lcLongitude = Double.parseDouble(rs.getString(7)); 
      String lcTelefone = rs.getString(8); 
      boolean lcEstado = Boolean.parseBoolean(rs.getString(9)); 
      String lcRua = rs.getString(10); 

      SQLloja loja = new SQLloja(lcId,lcNome,lcCP,lcDistrito,lcConselho,lcAltitude,lcLongitude,lcTelefone,lcEstado,lcRua); 

      listaLojas.put(loja.getNome(),loja.clone()); 

      String informacoesLoja = "Rua : "+lcRua+"\nC.P. : "+lcCP+"\nTel. : "+lcTelefone; 

      Log.d("ASYNC",lcNome+" Altitude = "+lcAltitude+" Longitude = "+lcLongitude+" Rua = "+lcRua); 
     } 
     //listaLoja = new SQLlistLoja(listaLojas); 
     rs.close(); 
     st.close(); 

    } catch (SQLException e) { 
     // TODO Auto-generated catch block 
     e.printStackTrace(); 
    } catch (ClassNotFoundException e) { 
     // TODO Auto-generated catch block 
     e.printStackTrace(); 
    } catch (Exception e) { 
    e.printStackTrace(); 
    } 

    if(listaLojas!=null){ 
     Log.d("ASYNC","entrei no if da listaLojas"); 
     for(SQLloja loja : listaLojas.values()){ 
      Log.d("ASYNC", loja.getNome()); 
     } 
    } 
    else Log.d("ASYNC","listaLoja nula ! PQP !"); 


     return listaLojas; 
    } 

    @Override 
    protected void onPostExecute(HashMap<String,SQLloja> listaLojas){ 
     listaLoja = listaLojas; 
     for(SQLloja loja : listaLoja.values()){ 
      Log.d("ASYNC24", loja.getNome()); 
     } 

    } 

} 

}

我米不知道，但是，我認爲從AsyncTask的返回值不是由正確的方式，雖然它的工作在我的Android應用程序。有些意見會受到歡迎。謝謝！ :)

來源

2013-05-21 Damiii

您使用AsyncTask是因爲您不希望任務掛起UI線程，特別是您不希望網絡任務延遲掛起。如果你在onCreate中做了一個AsyncTask.get（），你可以擊敗asynctask的目的。 –

那我該如何解決呢？ – Damiii

當你使用AsyncTask的時候，創建一個類實例來實現這些方法，然後當你想使用的時候，用方法.start（）創建一個變量asynctask;如果我沒有錯。它也很好創建ProgressDialog。

來源

2013-05-21 21:18:45

不知道是否可以安全地實現這樣的Asynctask

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