如何使用ProgressBar在等待来自服务器的httpResponse时显示微调器

Question

我试图在应用程序对在线数据库进行查询时向用户显示加载图标。我试过使用AnimationDrawable（我放弃了，因为不需要自定义图标），ProgressDialog和ProgressBar。 ProgressBar看起来最合适，因为我不想要消息，只是一个旋转的图标。但我甚至无法让ProgressBar出现在屏幕上，无论我在哪里调用它。 我有ProgressDialog出现在屏幕上，但它只出现在服务器的响应后，如果我使用dismiss（）或cancel（）它甚至不出现。

我已经使用AsyncTasks或线程成功。

在应用程序中，有一个类JogarActivity.java试图显示选项列表。它接收一些参数，如用户ID，并调用UserFunctions：

public void onCreate（Bundled savedInstanceState）{ super.onCreate（savedInstanceState）;

setContentView(R.layout.jogar_layout); 
    Intent in = getIntent(); 
    String url = this.getString(R.string.urlSite); 
    ArrayList<HashMap<String, String>> respostaList = new ArrayList<HashMap<String, String>>(); 

    String idt = in.getStringExtra(TAG_ID); 
    primeiraPergunta = in.getBooleanExtra(TAG_PRIMEIRAPERGUNTA, true); 

    TextView insertPergunta = (TextView) findViewById(R.id.insertPergunta); 
    ListView insertRespostas = (ListView) findViewById(R.id.listResposta); 

    SharedPreferences settings = getSharedPreferences("PREFS_LOGIN", MODE_PRIVATE); 
    Integer idUsuario = settings.getInt("idUsuario", 0); 
    String idUser = idUsuario.toString(); 


    if (primeiraPergunta){ 
     UserFunctions userFunction = new UserFunctions(); 
     json = userFunction.getJogar(idt, idUser); 
    }else{ 
     try { 
      json = new JSONArray(in.getStringExtra(TAG_JSON)); 
      json = json.getJSONArray(2); 
     } catch (JSONException e) { 
      e.printStackTrace(); 
     } 
    } 

下面是userFunctions的getJogar功能： 公共JSONArray getJogar（字符串categoria，字符串usuarioId）{ 列表PARAMS =新的ArrayList（）;

params.add(new BasicNameValuePair("categoria", categoria)); 
    params.add(new BasicNameValuePair("idUsuario", usuarioId)); 
    JSONArray json = jsonParser.getJSONFromUrl(perguntaURL, params); 

    return json; 
} 

JSONParser.java是使的HttpRequest类： 公共JSONArray getJSONFromUrl（字符串URL，列表PARAMS）{

// Making HTTP request 
    try { 
     // defaultHttpClient 
     HttpClient httpClient = new DefaultHttpClient(); 
     HttpPost httpPost = new HttpPost(url); 
     httpPost.setEntity(new UrlEncodedFormEntity(params)); 



     HttpResponse httpResponse = httpClient.execute(httpPost); 
     HttpEntity httpEntity = httpResponse.getEntity(); 



     // json = EntityUtils.toString(httpEntity); 
     // HttpEntity httpEntity2 = httpEntity; 
     json = EntityUtils.toString(httpEntity); 
     // is = httpEntity.getContent(); 

    } catch (UnsupportedEncodingException e) { 
     e.printStackTrace(); 
    } catch (ClientProtocolException e) { 
     e.printStackTrace(); 
    } catch (IOException e) { 
     e.printStackTrace(); 
    } 
      //then makes the JSON manipulation 

只要JSONParser和userFunctions都没有活动，我不能在他们内部不使用ProgressDialogs（无法获取应用程序上下文）。所有服务器请求都是在JSONParser.java中完成的，这就是为什么我第一次尝试将ProgressDialog/ProgressBar放在那里。

，我已经用在JogarActivity（它显示ProgressDialog，但得到服务器的响应后，如果我用辞退，甚至不出现的话）

final ProgressDialog loader = new ProgressDialog(JogarActivity.this); 
    loader.show(); 
    //...the if-else code i've pasted above 
    loader.dismiss(); 

即使该代码达到最接近使用runOnUiThread它不起作用！我没有选择...

感谢您的一切帮助。

Answer 1

这工作：

public class RegisterActivity extends Activity{ 
EditText reg_fullname; 
EditText reg_email; 
EditText reg_login; 
EditText reg_password; 
EditText reg_password2; 
Spinner reg_country; 
Spinner reg_genre; 
EditText reg_birthday; 
EditText reg_promocode; 
Button btnRegister; 
Context ctx = this; 
ProgressDialog pDialog; 
JSONArray json; 
String status; 
String msg; 

String fullname; 
String email; 
String login; 
String password; 
String password2; 
String country; 
String genre; 
String birthday; 
String promocode; 

boolean finishActivity = false; 

/** 
* @see android.app.Activity#onCreate(Bundle) 
*/ 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 

    setContentView(R.layout.register); 

    TextView loginScreen = (TextView) findViewById(R.id.link_to_login); 

    loginScreen.setOnClickListener(new View.OnClickListener() { 

     public void onClick(View arg0) { 
          // Closing registration screen 
      // Switching to Login Screen/closing register screen 
      finish(); 
     } 
    }); 

    reg_fullname = (EditText) findViewById(R.id.reg_fullname); 
    reg_email = (EditText) findViewById(R.id.reg_email); 
    reg_login = (EditText) findViewById(R.id.reg_login); 
    reg_password = (EditText) findViewById(R.id.reg_password); 
    reg_password2 = (EditText) findViewById(R.id.reg_password2); //confirmação de senha 
    reg_country = (Spinner) findViewById(R.id.reg_country); 
    reg_genre = (Spinner) findViewById(R.id.reg_genre); 
    reg_birthday = (EditText) findViewById(R.id.reg_birthday); 
    reg_promocode = (EditText) findViewById(R.id.reg_promocode); 

    btnRegister = (Button) findViewById(R.id.btnRegister); 


    btnRegister.setOnClickListener(new View.OnClickListener() { 

     @Override 
     public void onClick(View v) { 

      fullname = reg_fullname.getText().toString(); 
      email = reg_email.getText().toString(); 
      login = reg_login.getText().toString(); 
      password = reg_password.getText().toString(); 
      password2 = reg_password2.getText().toString(); 
      country = reg_country.getSelectedItem().toString(); 
      genre = reg_genre.getSelectedItem().toString(); 
      birthday = reg_birthday.getText().toString(); 
      promocode = reg_promocode.getText().toString(); 

      boolean validation = true; 
      String message = "Campo de preencimento obrigatório"; 

      if(fullname.equalsIgnoreCase("")){ 
       reg_fullname.setError(message); 
       validation = false; 
      } 
      if(email.equalsIgnoreCase("")){ 
       reg_email.setError(message); 
       validation = false; 
      } 
      if(!email.matches(".*@.*")){ 
       reg_email.setError("O endereço de email não é válido"); 
       validation = false; 
      } 
      if(login.equalsIgnoreCase("")){ 
       reg_login.setError(message); 
       validation = false; 
      } 
      if(password.equalsIgnoreCase("")){ 
       reg_password.setError(message); 
       validation = false; 
      } 
      if(password2.equalsIgnoreCase("")){ 
       reg_password2.setError(message); 
       validation = false; 
      } 
      if(!password.equals(password2)){ 
       reg_password2.setError("A confirmação de senha não confere"); 
       validation = false; 
      } 
      if(birthday.equalsIgnoreCase("")){ 
       reg_birthday.setError(message); 
       validation = false; 
      } 
      SimpleDateFormat bd = new SimpleDateFormat("dd/MM/yyyy"); 
      if(bd.parse(birthday, new ParsePosition(0)) == null){ 
       reg_birthday.setError("Esta data não é válida! Preencha novamente, usando o formato dd/mm/aaaa"); 
       validation = false; 
      } 

      if(validation){ 
      new Register().execute(); 
      } 

     } 
    }); 



} 


class Register extends AsyncTask<Void, Void, JSONArray>{ 

@Override 
protected void onPreExecute() { 
    super.onPreExecute(); 
    pDialog = new ProgressDialog(ctx); 
    pDialog.setMessage("Aguarde..."); 
    pDialog.setIndeterminate(true); 
    pDialog.setCancelable(false); 
    pDialog.show(); 
} 

@Override 
protected JSONArray doInBackground(Void... params) { 
    UserFunctions userFunction = new UserFunctions(); 
    json = userFunction.newUser(fullname, email, login, password, country, genre, birthday, promocode); 

    return json; 

} 

protected void onPostExecute(JSONArray result) { 
    // dismiss the dialog once done 
    pDialog.dismiss(); 
    final AlertDialog alertDialog = new AlertDialog.Builder(
      RegisterActivity.this).create(); 

      try { 
       status = json.getString(0); 
       msg = json.getString(1); 
       Log.d("Status", status); 
      } catch (JSONException e) { 
       Log.e("RegisterActiviry", "Error converting result " + e.toString()); 
       e.printStackTrace(); 
       status = null; 
      } 

      if (status.equalsIgnoreCase("erro")){ 
       alertDialog.setTitle("Erro"); 
       alertDialog.setMessage(msg); 

      }else if (status.equalsIgnoreCase("sucesso")){ 
       alertDialog.setTitle("Sucesso!"); 
       alertDialog.setMessage(msg); 
       finishActivity = true; 
      }else{ 
       alertDialog.setTitle("Erro"); 
       alertDialog.setMessage("Não foi possível realizar seu cadastro, tente novamente mais tarde."); 
      } 


      alertDialog.setButton("OK", new DialogInterface.OnClickListener() { 
       public void onClick(DialogInterface dialog, int which) { 
        if(finishActivity){ 
        finish(); 
        }else{ 
         alertDialog.dismiss(); 
        } 
       } 
     }); 

     alertDialog.show(); 

} 

} 


}