我正在开发我的第一个Android应用程序，我需要显示ProgressDialog而后台任务，在这种情况下只是服务器上的http调用。 我对此进行了一些研究，并且已经检查了与此主题相关的其他线程。
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
其中。
我要编写一些代码：
1）在My Activity中，我声明一个变量为ProgressDialog
类型public class LoginActivity extends Activity {
public static final String TAG = "LoginActivity";
protected ProgressDialog progressDialog;
...
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）当按下按钮时，我构建了ProgressDialog和调用我创建的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);
嗯，就是这样，我相信这是假设显示一个进度对话框，而AsyncTask会在后台查询服务器，但我得到的是没有进度条，直到服务器响应到达而且只有一小部分时间（少于超过1秒）进度显示并调用下一个活动。
正如我所提到的，我已经重新检查了这段代码，根本无法找到错误的地方。 有什么建议吗？
提前谢谢。
嗨，正如Charlie Sheen（???）在这个帖子的第一个答案中所建议的，我试过改变我的一些代码，现在它就像（不幸的是它到目前为止没有按预期工作）：
OnClickListener loginListener = new OnClickListener() {
public void onClick(View v) {
//async call????????
new EfetuaLogin().execute(params);
...
而不是在AsyncTask中处理响应的所有工作：
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();
}
}
完成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(".+@.+\\.[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);
}
};
答案 0 :(得分：29)
将ProgressDialog放入onPreExecute，示例代码如下：
private ProgressDialog pdia;
@Override
protected void onPreExecute(){
super.onPreExecute();
pdia = new ProgressDialog(yourContext);
pdia.setMessage("Loading...");
pdia.show();
}
@Override
protected void onPostExecute(String result){
super.onPostExecute(result);
pdia.dismiss();
}
并在onClickListener中，只需将此行放入：
new EfetuaLogin().execute(null, null , null);
答案 1 :(得分：8)
有效的最终解决方案是从OnClickListener实施doInBackground到AsyncTask方法的所有代码。现在代码就像：
OnClickListener：
OnClickListener loginListener = new OnClickListener() {
public void onClick(View v) {
/* Translation note: Original text: "Executando OnClickListener" */
Log.d(TAG, "OnClickListener has been called");
/* Translation note: Original text: "faz chamada assincrona" */
// Make an asynchronous call
new EfetuaLogin().execute();
}
};
所有工作都在EfetuaLogin AsyncTask实施中进行：
class EfetuaLogin extends AsyncTask<Object, Void, String> {
private final static String TAG = "LoginActivity.EfetuaLogin";
protected ProgressDialog progressDialog;
@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
/* Translation note: Original text: "Object... parametros"
protected String doInBackground(Object... parameters) {
/* Translation note: Original text: "Executando doInBackground de EfetuaLogin" */
Log.d(TAG, "Executing doInBackground of EfetuaLogin");
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("")) {
/*
Translation notes:
1) "Campos Obrigatórios" -> "Required fields"
2) "Os campos Login e Senha são obrigatórios para autenticação do Anototudo." -> "Login and Password fields are required for Anototudo authentication."
Alerta.popupAlertaComBotaoOK("Required fields", "Login and Password fields are required for Anototudo authentication.", LoginActivity.this);
progressDialog.dismiss();
return null;
} else {
Pattern regEx = Pattern.compile(".+@.+\\.[a-z]+");
Matcher matcher = regEx.matcher(sLogin);
if (!matcher.matches()) {
/*
Translation notes:
1) "Formato e-mail inválido" -> "Invalid email format"
2) "O formato do campo e-mail está inválido" -> "The email field has an invalid format"
*/
Alerta.popupAlertaComBotaoOK("Invalid email format", "The email field has an invalid format",
LoginActivity.this);
progressDialog.dismiss();
return null;
}
}
List<NameValuePair> listaParametros = new ArrayList<NameValuePair>();
listaParametros.add(new BasicNameValuePair("login", sLogin));
listaParametros.add(new BasicNameValuePair("senha", sSenha));
/* Translation note: Original text: "valores recuperados dos campos de login e senha: " */
Log.d(TAG, "values retrieved from login and password fields:" + sLogin + " | " + sSenha);
/* Translation note: Original text: "Reutiliza cliente HttpClient disponibilizado pela Aplicação." */
// Reuses `HttpClient` made available by the Application.
AnototudoApp atapp = (AnototudoApp) LoginActivity.this.getApplication();
HttpClient httpClient = atapp.getHttpClient();
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();
/*
Translation notes:
1) "Dados incorretos" -> "Incorrect data"
2) "Os dados informados não foram encontrados no Sistema! Informe novamente ou cadastre-se antes pela internet." -> "The reported data was not found in the System! Please report again or sign up on the internet first."
*/
Alerta.popupAlertaComBotaoOK(
"Incorrect data",
"The reported data was not found in the System! Please report again or sign up on the internet first.",
LoginActivity.this);
return;
}
/* Translation note: Original text: "Login passou persistindo info de login local no device" */
Log.d(TAG, "Login passed persisting local login info on 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);
/* Translation note: Original text: "Persistiu info de login no device, redirecionando para menu principal do Anototudo" */
Log.d(TAG, "Persisting login info on device, redirecting to Anototudo main menu");
/* Translation note: Original text: "O retorno da chamada foi ==>> " */
Log.d(TAG, "The callback was ==>>" + result);
/* Translation note: Original text: "tudo ok chama menu principal" */
// everything ok call main menu
/* Translation note: Original text: "Device foi corretametne autenticado, chamando tela do menu principal do Anototudo." */
Log.d(TAG, "Device has been correctly authenticated by calling the main menu screen of Annotate.");
String actionName = "br.com.anototudo.intent.action.MainMenuView";
Intent intent = new Intent(actionName);
LoginActivity.this.startActivity(intent);
progressDialog.dismiss();
}
}
现在它按预期工作但我不得不说我有点困惑，因为AsyncTask文档说你可以使用execute将参数传递给你的任务。