[英]Do i implement alert dialog in async task or not?
我試圖顯示我的Login類中是否存在Internet連接。 還有另一個連接管理器類，如果沒有互聯網連接，該類將顯示一個警告對話框，但是我對在哪里實現代碼感到困惑，因為Login類中還有一個異步任務（嘗試登錄），任何人都可以告訴我在哪里放置我的代碼，我在哪里出錯？
public class LoginActivity extends Activity implements OnClickListener {
// flag for Internet connection status
Boolean isInternetPresent = false;
// Connection detector class
ConnectionDetector cd;
EditText username, password;
Button login;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
// creating connection detector class instance
cd = new ConnectionDetector(getApplicationContext());
/**
* Check Internet status button click event
* */
username = (EditText) findViewById(R.id.username_et);
password = (EditText) findViewById(R.id.password_et);
login = (Button) findViewById(R.id.login_bt);
login.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// get Internet status
isInternetPresent = cd.isConnectingToInternet();
// check for Internet status
if (isInternetPresent) {
// Internet Connection is Present
// make HTTP requests
showAlertDialog(LoginActivity.this, "Internet Connection",
"You have internet connection", true);
} else {
// Internet connection is not present
// Ask user to connect to Internet
showAlertDialog(LoginActivity.this, "No Internet Connection",
"You don't have internet connection.", false);
}
String name = username.getText().toString();
String pass = password.getText().toString();
new AttemptLogin().execute(name, pass);
}
public void showAlertDialog(Context context, String title, String message, Boolean status) {
AlertDialog alertDialog = new AlertDialog.Builder(context).create();
// Setting Dialog Title
alertDialog.setTitle(title);
// Setting Dialog Message
alertDialog.setMessage(message);
// Setting alert dialog icon
alertDialog.setIcon((status) ? R.drawable.success : R.drawable.fail);
// Setting OK Button
alertDialog.setButton("OK", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
}
});
// Showing Alert Message
alertDialog.show();
}
});
}
private class AttemptLogin extends
AsyncTask<String, Integer, String> {
int success;
String message = " ", _username, _password;
@Override
protected String doInBackground(String... args) {
_username = args[0];
_password = args[1];
try {
Map<String, String> params = new HashMap<String, String>();
params.put("tag", "login");
params.put("username", _username);
params.put("password", _password);
HttpUtility.sendPostRequest(params);
String response = HttpUtility.readRespone();
JSONObject jObj = null;
try {
jObj = new JSONObject(response);
success = jObj.getInt("success");
message = jObj.getString("message");
} catch (JSONException e) {
Log.e("JSON Parser", "Error parsing data" + e.toString());
}
} catch (IOException ex) {
ex.printStackTrace();
}
HttpUtility.disconnect();
return message;
}
protected void onPostExecute(String status) {
if (status != null) {
Toast.makeText(getBaseContext(), status, Toast.LENGTH_LONG).show();
if (success == 1) {
SharedPreference.store(getApplicationContext(), _username, _password);
startActivity(new Intent(getBaseContext(), DashboardActivity.class));
}
}
}
}
}
我已在代碼中添加了注釋，以幫助闡明應在何處執行所討論的邏輯。
要回答您的問題：不要從AsyncTask創建警報對話框。 流程如下：
請讓我知道，如果你有任何問題。
public class LoginActivity extends Activity implements OnClickListener {
// flag for Internet connection status
Boolean isInternetPresent = false;
// Connection detector class
ConnectionDetector cd;
EditText username, password;
Button login;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
// creating connection detector class instance
cd = new ConnectionDetector(getApplicationContext());
/**
* Check Internet status button click event
* */
username = (EditText) findViewById(R.id.username_et);
password = (EditText) findViewById(R.id.password_et);
login = (Button) findViewById(R.id.login_bt);
login.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// get Internet status
isInternetPresent = cd.isConnectingToInternet();
// check for Internet status
if (isInternetPresent) {
***********************************************
I moved your code to show a dialog to the beginning of the
if block where you have internet. I also changed your dialog
to a Toast message, as others have suggested. Dialog is a little
too heavy for this in my opinion.
***********************************************
// Internet Connection is Present
// make HTTP requests
// showAlertDialog(LoginActivity.this, "Internet Connection",
// "You have internet connection", true);
Toast
.makeText(this, "You have internet connection", Toast.LENGTH_LONG)
.show();
***********************************************
Assuming that your isConnectingToInternet method returns
the correct value, within this if statement, you know that
you have a valid Internet connection. Go ahead and fire offf
your AsyncTask here.
I moved this code from after your if / else statement to within the
if / else statement once you verify that the device has an Internet
connection. AGAIN: This is assuming that your isConnectingToInternet
returns a proper value. I did not look at that code.
**********************************************
String name = username.getText().toString();
String pass = password.getText().toString();
new AttemptLogin().execute(name, pass);
} else {
***********************************************
This logic remains the same. Think about it:
If the user doesn't have Internet connection, you can't make a login
request.
***********************************************
// Internet connection is not present
// Ask user to connect to Internet
showAlertDialog(LoginActivity.this, "No Internet Connection",
"You don't have internet connection.", false);
}
}
public void showAlertDialog(Context context, String title, String message, Boolean status) {
AlertDialog alertDialog = new AlertDialog.Builder(context).create();
// Setting Dialog Title
alertDialog.setTitle(title);
// Setting Dialog Message
alertDialog.setMessage(message);
// Setting alert dialog icon
alertDialog.setIcon((status) ? R.drawable.success : R.drawable.fail);
// Setting OK Button
alertDialog.setButton("OK", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
}
});
// Showing Alert Message
alertDialog.show();
}
});
}
private class AttemptLogin extends
AsyncTask<String, Integer, String> {
int success;
String message = " ", _username, _password;
@Override
protected String doInBackground(String... args) {
_username = args[0];
_password = args[1];
try {
Map<String, String> params = new HashMap<String, String>();
params.put("tag", "login");
params.put("username", _username);
params.put("password", _password);
HttpUtility.sendPostRequest(params);
String response = HttpUtility.readRespone();
JSONObject jObj = null;
try {
jObj = new JSONObject(response);
success = jObj.getInt("success");
message = jObj.getString("message");
} catch (JSONException e) {
Log.e("JSON Parser", "Error parsing data" + e.toString());
}
} catch (IOException ex) {
ex.printStackTrace();
}
HttpUtility.disconnect();
return message;
}
protected void onPostExecute(String status) {
if (status != null) {
Toast.makeText(getBaseContext(), status, Toast.LENGTH_LONG).show();
if (success == 1) {
SharedPreference.store(getApplicationContext(), _username, _password);
startActivity(new Intent(getBaseContext(), DashboardActivity.class));
}
}
}
}
使用此類檢查互聯網連接...
public class CheckNetwork {
private Context context;
public CheckNetwork(Context context) {
this.context = context;
}
public boolean isNetworkAvailable() {
ConnectivityManager connectivityManager = (ConnectivityManager) context
.getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo activeNetworkInfo = connectivityManager
.getActiveNetworkInfo();
return activeNetworkInfo != null && activeNetworkInfo.isConnected();
}
}
然后.....
使用此ASyncTask進行登錄嘗試。
public class AttemptLogin extends AsyncTask<String, Void, String> {
private ProgressDialog dialog;
@Override
protected void onPreExecute() {
dialog = new ProgressDialog(LoginActivity.this);
dialog.setMessage("Loading...");
dialog.setCancelable(false);
dialog.show();
super.onPreExecute();
}
@Override
protected String doInBackground(String... arg0) {
if (new CheckNetwork(LoginActivity.this).isNetworkAvailable() {
// your get/post related code...
} else {
Toast.makeText(LoginActivity.this, "no internet!", Toast.LENGTH_SHORT).show();
}
return null;
}
@Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
if (dialog.isShowing()) {
dialog.dismiss();
}
}
}
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