我正在尝试从网络服务器获取数据并显示一条消息“确定”或“无效 key ”。当它获取数据时，它应该产生一个进度对话框。我尝试了很多方法，包括将其放入线程内，但是在线程内，警报对话框将不起作用。我尝试过使用异步任务方法，但它似乎也不起作用。有人可以帮我找到解决方案吗？谢谢
verifyCode.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View arg0) {
//I surround the async task with the progressdialog so that it should show while the method is working in the background
final ProgressDialog progressDialog = ProgressDialog.show(
Activate.this, "", "Loading...");
new checkActivationCode().execute(activationCode.toString().toUpperCase()
);
progressDialog.dismiss();
}
});
public class checkActivationCode extends AsyncTask<String, Void, Void> {
@Override
protected Void doInBackground(String... activationCode) {
// TODO Auto-generated method stub
try {
DefaultHttpClient httpclient = new DefaultHttpClient();
HttpPost httpost = new HttpPost(
"https://iphone-radar.com/accounts/confirmation");
JSONObject holder = new JSONObject();
holder.put("code", activationCode);
StringEntity se = new StringEntity(holder.toString());
httpost.setEntity(se);
httpost.setHeader("Accept", "application/json");
httpost.setHeader("Content-type", "application/json");
ResponseHandler responseHandler = new BasicResponseHandler();
String response = httpclient.execute(httpost, responseHandler);
if (response != null) {
org.json.JSONObject obj = new org.json.JSONObject(response);
if ("00000000-0000-0000-0000-000000000000".equals(obj
.getString("id"))) {
new AlertDialog.Builder(Activate.this)
.setTitle(
getResources().getString(
R.string.InvalidKey))
.setMessage(
getResources()
.getString(
R.string.PleaseEntervalidRegistration))
.setNeutralButton("OK", null).show();
} else {
// add permanent variables
SharedPreferences prefs = getSharedPreferences(
"Settings", 0);
SharedPreferences.Editor editor = prefs.edit();
editor.putBoolean("ACTIVATED", true);
editor.putString("ID", obj.getString("id"));
editor.commit();
Intent imTracking = new Intent(Activate.this,
ImTracking.class);
imTracking.putExtra("ActivationSuccessful", true);
// transfer more data
startActivity(imTracking);
}
}
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (UnsupportedEncodingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (ClientProtocolException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return null;
}
}
最佳答案
您无法通过 doInBackground() 方法显示任何类型的对话框或进度对话框，因为它不在 UI 线程上运行。您将需要使用 onProgressUpdate() 方法通过进度更新来更新 UI。如果您想在完成时显示 AlertDialog，请使用 onPostExecute() 方法。 onProgressUpdate() 和 onPostExecute() 都在 UI 线程上运行，因此您的 AlertDialog 代码将正常工作。
这里是 AsyncTask 页面，其中包含一些有关如何正确使用它的示例代码(包括在何处提供 UI 更新):http://developer.android.com/reference/android/os/AsyncTask.html
这里有一些涉及同一主题的问题:How to use AsyncTask to show a ProgressDialog while doing background work in Android?
Updating progress dialog in Activity from AsyncTask
How can I remove an alert dialog after a AsyncTask has done it's work
关于java - 异步任务的问题，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/7071364/