5
我有一個應用程序，它在遍歷文件系統（每個文件夾一個活動）時遞歸地創建一個活動的多個實例。在活動堆棧中向前移動時（即正常文件夾遍歷），我通過Intent檢索數據。當我從父文件夾到子文件夾時，應用程序運行良好。我遇到問題，因爲文件/文件夾的列表與之前的活動（孩子）保持不變。我不想再從互聯網上檢索文件夾數據，因此可以跟蹤以前的活動狀態？這是我的活動的一段代碼。由於迴歸遞歸活動（FileSystem like）
public class RisorseActivity extends DashboardActivity implements Observer {
private Docente docente;
private String get_response;
private String response;
//private HttpsClient client;
private ListView list;
private RelativeLayout progressLayout;
private ProgressBar progressBar;
private TextView txtMateriale;
private ArrayList<Risorsa> risorseList;
private RisorseAdapter risAdapter;
private RisorseList risList;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_risorse);
setTitleFromActivityLabel(R.id.title_text);
list = (ListView) findViewById(R.id.ListRisorse);
list.setClickable(true);
Intent intent = getIntent();
// vengono recuperati i parametri dalla activity chiamante
docente = (Docente) intent.getSerializableExtra(getPackageName() + ".Docente");
//cartella = (Insegnamento) intent.getSerializableExtra(pkg + ".Insegnamento");
get_response = intent.getExtras().getString("get_response");
response = intent.getExtras().getString("response");
list.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> arg0, View view,
int position, long index) {
if (risorseList.get(position).getType().equalsIgnoreCase("Folder")) {
Intent intRisorse = new Intent(getApplicationContext(), RisorseActivity.class);
intRisorse.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
intRisorse.putExtra(getPackageName() + ".Docente", docente);
intRisorse.putExtra("get_response", risorseList.get(position).getURL());
startActivity(intRisorse);
} else if (risorseList.get(position).getType().equalsIgnoreCase("File")) {
//--------------- DOWNLOAD DEL FILE-------------------
}
}
});
startRisorseService();
}
// Aggiorna la View della Activity popolando la lista dei docenti trovati
private void updateView() {
this.risAdapter = new RisorseAdapter(this, this.risorseList);
if (this.risAdapter != null) {
this.list.setAdapter(this.risAdapter);
} else {
Toast.makeText(this, "Errore caricamento lista materiale",
Toast.LENGTH_LONG).show();
}
}
private void startRisorseService() {
// risList conterrà il nostro modello dei dati (l'array di oggetti
// Ricevimento)
risList = RisorseList.getInstance();
if (risList.countObservers() == 0)
risList.addObserver(this); // aggiungiamo la nostra "View" come
// osservatore del modello dati
loginState = ((LoginState) getApplicationContext());
Handler handler = new RisorseHandler();
//IT IS THE TASK THATH RETRIEVE THE DATA
RisorseService task = null;
if (response != null){
task = new RisorseService(handler, loginState, response);
}else
task = new RisorseService(handler, loginState);
if (task != null)
task.execute(get_response);
}
public void update(Observable observable, Object arg1) {
if(observable instanceof RisorseList){
// in quanto potremmo avere piu modelli dati
// verifichiamo su quale modello è avvenuto un cambiamento dei dati
// prima di effettuare il cast
this.risorseList = ((RisorseList) observable).getData();
}
updateView();
risList.deleteObserver(this);
}
public void onClickRefresh(View v) {
startRisorseService();
}
@Override
protected void onResume(){
super.onResume();
// IF I UNCOMMENT THESE LINES IT WORK BUT RETRIEVE DATA FROM INTERNET AGAIN!!!
/*if (risAdapter == null)
startRisorseService();
else{
risAdapter.notifyDataSetChanged();
}*/
if (risAdapter != null)
updateView();
}
}