用asynctask更新列表視圖（Json）

Question

我遇到了麻煩，試圖使用asynctask更新列表視圖。 的的AsyncTask似乎並沒有被連接到數據庫...

我一直在尋找，但我無法找到解決辦法......

感謝您的幫助！

這裏是源代碼：

@SuppressLint("NewApi") 
public class Resultats extends Activity { 

private PullToRefreshListView lv1; 

private ImageView refresh = null; // to refresh 

private ArrayList<Match_ItemDetails> image_details; 
private Resultats_ListBaseAdapter adapter; 
private ArrayList<Match_ItemDetails> results; 

/** Called when the activity is first created. */ 

@Override 
public void onCreate(Bundle savedInstanceState) { 
super.onCreate(savedInstanceState); 
setContentView(R.layout.resultats); 

results = new ArrayList<Match_ItemDetails>(); 

// first construction 

image_details = GetSearchResults(); 
adapter = new Resultats_ListBaseAdapter(this, image_details); 

// Définition de la liste 
lv1 = (PullToRefreshListView) findViewById(R.id.liste); 

// to refresh 

refresh = (ImageView)findViewById(R.id.resultats_refresh); 
refresh.setOnClickListener(new View.OnClickListener() { 

    @Override 
    public void onClick(View v) { 
     refresh(GetSearchResults());   
    } 
}); 
lv1.setAdapter(new Resultats_ListBaseAdapter(this, image_details)); 

//Listener that will be invoked when it has been tap or it has been pull and released 
lv1.setOnRefreshListener(new OnRefreshListener() { 
      @Override 
      public void onRefresh() { 

       new GetDataTask().execute(); 

      } 
     }); 
} 

// refresh 
private void refresh(ArrayList<Match_ItemDetails> arrayList){ 
    lv1.setAdapter(new Resultats_ListBaseAdapter(this, arrayList)); 

} 

// asynctask which isn t working 


private class GetDataTask extends AsyncTask<Void, Void, ArrayList<Match_ItemDetails>> { 
    ArrayList<Match_ItemDetails> tableau; 

    @Override 
    protected ArrayList<Match_ItemDetails> doInBackground(Void... params) { 
      Log.i(MainActivity.class.getName(),"doinBackground"); 
      StrictMode.ThreadPolicy policy = new   StrictMode.ThreadPolicy.Builder().permitAll().build(); 
      StrictMode.setThreadPolicy(policy); 
      tableau = GetSearchResults(); 
      System.out.println("pouet"); 
     return tableau; 
    } 

    @Override 
    protected void onPostExecute(ArrayList<Match_ItemDetails> result) { 
      refresh(result); 
      lv1.onRefreshComplete(); 

    } 
} 


// construction of the arraylist 

private ArrayList<Match_ItemDetails> GetSearchResults(){ 

    StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build(); 
    StrictMode.setThreadPolicy(policy); 

    String lireResultats = lireResultats(); 

    try { 
     JSONArray jsonArray = new JSONArray(lireResultats); 
     Log.i(MainActivity.class.getName(), 
      "Number of entries " + jsonArray.length()); 
     for (int i = 0; i < jsonArray.length(); i++) { 
     JSONObject jsonObject = jsonArray.getJSONObject(i); 
     Match_ItemDetails item_details = new Match_ItemDetails(); 
     item_details.setNameTeam1(jsonObject.getString("equipe1")); 
     item_details.setNameTeam2(jsonObject.getString("equipe2")); 
     item_details.setDate(jsonObject.getString("date")); 
     item_details.setScoreTeam1(jsonObject.getInt("scoreEquipe1")); 
     item_details.setScoreTeam2(jsonObject.getInt("scoreEquipe2")); 
     item_details.setEstFini(jsonObject.getInt("estFini")); 
     item_details.setDrapeauEquipe1(jsonObject.getString("drapeauEquipe1")); 
     item_details.setDrapeauEquipe2(jsonObject.getString("drapeauEquipe2")); 
     if (!existe(item_details.getDrapeauEquipe1())){ 
      enregistrer(item_details.getDrapeauEquipe2());    
     } 
     if (!existe(item_details.getDrapeauEquipe2())){ 
      enregistrer(item_details.getDrapeauEquipe2()); 
     } 
     item_details.setDrapeau1(getImage(item_details.getDrapeauEquipe1())); 
     item_details.setDrapeau2(getImage(item_details.getDrapeauEquipe2())); 

     results.add(item_details); 
     } 
    } catch (Exception e) { 
     e.printStackTrace(); 
    } 

    return results; 
} 


// get data 

public String lireResultats() { 
StringBuilder builder = new StringBuilder(); 
HttpClient client = new DefaultHttpClient(); 
HttpGet httpGet = new HttpGet("****/resultats.php"); 
try { 
    HttpResponse response = client.execute(httpGet); 
    StatusLine statusLine = response.getStatusLine(); 
    int statusCode = statusLine.getStatusCode(); 
    if (statusCode == 200) { 
    HttpEntity entity = response.getEntity(); 
    InputStream content = entity.getContent(); 
    BufferedReader reader = new BufferedReader(new InputStreamReader(content)); 
    String line; 
    while ((line = reader.readLine()) != null) { 
     builder.append(line); 
    } 
    } else { 
    Log.e(MainActivity.class.toString(), "Failed to download file"); 
    } 
} catch (ClientProtocolException e) { 
    e.printStackTrace(); 
} catch (IOException e) { 
    e.printStackTrace(); 
} 
return builder.toString(); 
} 

// test if the file exists 

public boolean existe(String nom){ 
    File tmp = new File(this.getFilesDir() + File.separator + nom); 
    return tmp.exists(); 
} 

// return a pict 
public Bitmap getImage(String nom){ 
    Bitmap drawable = BitmapFactory.decodeFile(this.getFilesDir() + File.separator + nom); 
    return drawable; 
} 

// save a pict 
public void enregistrer(String nom){ 
    try 
    { 
URL u = new URL("http://www.centrale7.com/paris/android/drapeaux48/" + nom + ".png"); 
URLConnection conn = u.openConnection(); 
conn.connect(); 
InputStream is = new BufferedInputStream(conn.getInputStream()); 
Bitmap bm1 = BitmapFactory.decodeStream(is); 
// Bitmap bm1 = BitmapFactory.decodeResource(getResources(), R.drawable.test); 
FileOutputStream fout = openFileOutput(nom, Context.MODE_PRIVATE); 
bm1.compress(Bitmap.CompressFormat.PNG, 100, fout); 
      } 
    catch(Exception e){ 
    System.out.println("ca marche pas"); 
    System.out.println(e); 
    e.printStackTrace(); 
    } 
} 
} 

Answer 1

起初，因爲你正在使用的AsyncTask沒有必要調用

strictMode.ThreadPolicy 

你shoudn't調用它。只是執行JSON解析

tableau = GetSearchResults(); 
return tableau; 

，然後在你的刷新方法您適配器設置新的數據源後，你需要調用

adapter.notifyDataSetChanged(); 

適配器當您更改數據源不知道，也不會刷新自己。你需要通過調用上面提到的方法來確保它。