0

我在android上做了一个代码，我想从stackoverflow人那里得到一些意见。这是关于我使用 AsyncTask 类的代码......但我不知道它是否编码好......

这是代码：

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() );
        }

    }

}

}

我不确定，但我认为 AsyncTask 的返回值不是以正确的方式生成的，尽管它在我的 android 应用程序上工作。一些意见将受到欢迎。谢谢 ！:)

4

1 回答 1

0

当您使用 AsyncTask 时，最好创建一个类实例来实现方法，然后当您要使用时，使用方法 .start(); 创建一个变量 asynctask；如果我没记错的话。它也很好地创建了一个 ProgressDialog。

于 2013-05-21T21:18:45.293 回答