可能重複:
Updating progress dialog in Activity from AsyncTask如何使用AsyncTask在Android中進行後臺工作時顯示ProgressDialog?
我發展我的第一個Android應用程序,我需要一個ProgressDialog進行顯示,而後臺任務,在這種情況下,只是在服務器上的一個HTTP調用, 發生。 我做了一些研究,也已經檢查了與這個主題相關的其他線程。
http://developer.android.com/reference/android/os/AsyncTask.html
Android show ProgressDialog until activity UI finished loading
http://android-developers.blogspot.com/2009/05/painless-threading.html
等等。
比我寫一個位的代碼:
1)在我的活動我聲明一個變量是類型的ProgressDialog
public class LoginActivity extends Activity {
public static final String TAG = "LoginActivity";
protected ProgressDialog progressDialog;
...
2)I也寫一個內部類來擴展AsyncTask根據需要,這裏的doInBackGround是我調用一個靜態方法,它實際上對服務器執行POST HTTP請求,在服務器端,我已經阻止了服務器響應20秒來驗證進度對話框。
class EfetuaLogin extends AsyncTask<Object, Void, String> {
private final static String TAG = "LoginActivity.EfetuaLogin";
@Override
protected void onPreExecute()
{
Log.d(TAG, "Executando onPreExecute de EfetuaLogin");
}
@SuppressWarnings("unchecked")
@Override
protected String doInBackground(Object... parametros) {
Log.d(TAG, "Executando doInBackground de EfetuaLogin");
Object[] params = parametros;
HttpClient httpClient = (HttpClient) params[0];
List<NameValuePair> listaParametros = (List<NameValuePair>) params[1];
String result = null;
try{
result = HttpProxy.httpPost(AnototudoMetadata.URL_AUTENTICACAO, httpClient, listaParametros);
}catch (IOException e) {
Log.e(TAG, "IOException, Sem conectividade com o servidor do Anototudo! " + e.getMessage());
e.printStackTrace();
return result;
}
return result;
}
@Override
protected void onPostExecute(String result)
{
progressDialog.dismiss();
}
}
3)當按鈕被按下我比建ProgressDialog ANC叫我已創建的AsyncTask:
OnClickListener loginListener = new OnClickListener() {
public void onClick(View v) {
//next line should start progress dialog in main thread ?????
progressDialog = ProgressDialog.show(LoginActivity.this, "Login in", "Wait a moment please", true, false);
//next couple of lines should do an ascyn call to server
EfetuaLogin efetuaLogin = new EfetuaLogin();
efetuaLogin.execute(params);
try {
//recover the server response and sets time out to be 25seconds
sResposta = efetuaLogin.get(25, TimeUnit.SECONDS);
那麼,這是它,我相信這是假設顯示一個進度對話框而AsyncTask會在後臺查詢服務器,但我得到的是沒有進度條,直到服務器響應到達,並且進度顯示和下一個活動被調用的時間(小於1秒)。
正如我所提到的,我重新檢查了這段代碼,根本找不到錯誤的地方。 有什麼建議嗎?
預先感謝您。
嗨,正如Charlie Sheen所建議的那樣(???)在該線程的第一個答案我已經tryied改變了一下我的代碼,現在它像(可惜的是迄今爲止所預期它不工作):
OnClickListener loginListener = new OnClickListener() {
public void onClick(View v) {
//async call????????
new EfetuaLogin().execute(params);
...
而不是做所有處理工作響應中的AsyncTask:
class EfetuaLogin extends AsyncTask<Object, Void, String> {
private final static String TAG = "LoginActivity.EfetuaLogin";
@Override
protected void onPreExecute()
{
super.onPreExecute();
Log.d(TAG, "Executando onPreExecute de EfetuaLogin");
//inicia diálogo de progresso, mostranto processamento com servidor.
progressDialog = ProgressDialog.show(LoginActivity.this, "Autenticando", "Contactando o servidor, por favor, aguarde alguns instantes.", true, false);
}
@SuppressWarnings("unchecked")
@Override
protected String doInBackground(Object... parametros) {
Log.d(TAG, "Executando doInBackground de EfetuaLogin");
Object[] params = parametros;
HttpClient httpClient = (HttpClient) params[0];
List<NameValuePair> listaParametros = (List<NameValuePair>) params[1];
String result = null;
try{
result = HttpProxy.httpPost(AnototudoMetadata.URL_AUTENTICACAO, httpClient, listaParametros);
}catch (IOException e) {
Log.e(TAG, "IOException, Sem conectividade com o servidor do Anototudo! " + e.getMessage());
e.printStackTrace();
return result;
}
return result;
}
@Override
protected void onPostExecute(String result)
{
super.onPostExecute(result);
if (result == null || result.equals("")) {
progressDialog.dismiss();
Alerta
.popupAlertaComBotaoOK(
"Dados incorretos",
"Os dados informados não foram encontrados no Sistema! Informe novamente ou cadastre-se antes pela internet.",
LoginActivity.this);
return;
}
Log.d(TAG, "Login passou persistindo info de login local no device");
ContentValues contentValues = new ContentValues();
contentValues.put(AnototudoMetadata.LOGIN_EMAIL, sLogin);
contentValues.put(AnototudoMetadata.LOGIN_SENHA, sSenha);
contentValues.put(AnototudoMetadata.LOGIN_SENHA_GERADA, result);
LoginDB loginDB = new LoginDB();
loginDB.addLogin(LoginActivity.this, contentValues);
Log.d(TAG, "Persistiu info de login no device, redirecionando para menu principal do Anototudo");
Log.d(TAG, "O retorno da chamada foi ==>> " + result);
// tudo ok chama menu principal
Log.d(TAG, "Device foi corretametne autenticado, chamando tela do menu principal do Anototudo.");
String actionName = "br.com.anototudo.intent.action.MainMenuView";
Intent intent = new Intent(actionName);
LoginActivity.this.startActivity(intent);
progressDialog.dismiss();
}
}
完全OnClickListener:
OnClickListener loginListener = new OnClickListener() {
public void onClick(View v) {
Log.d(TAG, "Usuario logado, chamando menu principal");
TextView tLogin = (TextView) findViewById(R.id.loginText);
TextView tSenha = (TextView) findViewById(R.id.senhaText);
String sLogin = tLogin.getText().toString();
String sSenha = tSenha.getText().toString();
if (sLogin.equals("") | sSenha.equals("")) {
Alerta.popupAlertaComBotaoOK("Campos Obrigatórios",
"Os campos Login e Senha são obrigatórios para autenticação do Anototudo.", LoginActivity.this);
return;
} else {
Pattern regEx = Pattern.compile("[email protected]+\\.[a-z]+");
Matcher matcher = regEx.matcher(sLogin);
if (!matcher.matches()) {
Alerta.popupAlertaComBotaoOK("Formato e-mail inválido", "O formato do campo e-mail está inválido",
LoginActivity.this);
return;
}
}
List<NameValuePair> listaParametros = new ArrayList<NameValuePair>();
listaParametros.add(new BasicNameValuePair("login", sLogin));
listaParametros.add(new BasicNameValuePair("senha", sSenha));
Log.d(TAG, "valores recuperados dos campos de login e senha: " + sLogin + " | " + sSenha);
// Reutiliza cliente HttpClient disponibilizado pela Aplicação.
AnototudoApp atapp = (AnototudoApp) LoginActivity.this.getApplication();
HttpClient httpClient = atapp.getHttpClient();
//prepara lista de parametros para fazer chamada asíncrona no servidor para autenticar.
Object[] params = new Object[2];
params[0] = httpClient;
params[1] = listaParametros;
//faz chamada assincrona
new EfetuaLogin().execute(params);
}
};
我已經嘗試過這一點(將pD放在onPreExecute中)也沒有按預期工作。我也需要傳遞一些參數來執行任務,所以我不能使用execute(null),就像你提到的那樣。我可以嗎?請注意,我需要傳遞一些參數,並從AsyncTask中恢復響應,這就是爲什麼我要調用AsyncTask.get方法。 – 2010-10-08 19:44:28
@Marcos Maia:你創建一個你的'AsyncTask'對象並在其中存儲一個引用。在不創建參考的情況下執行它。 'AsyncTask'用於短操作,所以請檢查'onPostExecute'中的結果,而不是試圖通過引用來獲取響應。當你點擊你的'Button'時,你無法迅速獲得服務器響應。 – Wroclai 2010-10-08 19:49:11
@Moscos Maia:將所有必需的東西放在'doInBackground'中。 'doInBackground'的輸出結果傳遞給'onPostExecute'參數,在那裏你可以檢查你的服務器響應 - 所有這些在'AsyncTask'裏面。關於你傳遞給'AsyncTask'的值,我不能告訴你任何事情,因爲缺少一些代碼片段。 – Wroclai 2010-10-08 19:58:45