我正在尝试在用户等待来自网络服务的响应时出现“正在加载...”消息。
我已经看过各种其他类似的问题/答案以及我在网上找到的教程，但却无法让它正常运作。
非常感谢任何帮助！
代码在这里：
public class SunriseSunset extends Activity implements OnClickListener {
public Button getLocation;
public Button setLocationJapan;
public TextView LongCoord;
public TextView LatCoord;
public double longitude;
public double latitude;
public LocationManager lm;
public Spinner Locationspinner;
public DateDialogFragment frag;
public Button date;
public Calendar now;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.sunrisesunset);
// Show the Up button in the action bar.
setupActionBar();
//Setting onClickListener for Calculate Sunrise/Sunset Button
findViewById(R.id.CalculateSunriseSunset).setOnClickListener(this);
//Sets up LocationManager to enable GPS data to be accessed.
lm = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
lm.requestLocationUpdates(LocationManager.GPS_PROVIDER, 1000, 1,
new MyLocationListener());
//Declares Latitude and Longitude TextViews
LatCoord = (TextView) findViewById(R.id.LatCoord);
LongCoord = (TextView) findViewById(R.id.LongCoord);
//Declares for Location Spinner/Dropdown
addListenerOnSpinnerItemSelection();
//Date shit
now = Calendar.getInstance();
date = (Button)findViewById(R.id.date_button);
date.setText(DateFormat.format("dd MMMM yyyy", Calendar.getInstance()));
date.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
showDialog();
}
});
}
/**
* Set up the {@link android.app.ActionBar}.
*/
private void setupActionBar() {
getActionBar().setDisplayHomeAsUpEnabled(true);
}
// More date shit
@SuppressLint("CommitTransaction")
public void showDialog() {
FragmentTransaction ft = getFragmentManager().beginTransaction(); //get the fragment
frag = DateDialogFragment.newInstance(this, new DateDialogFragmentListener(){
public void updateChangedDate(int year, int month, int day){
now.set(year, month, day);
date.setText(DateFormat.format("dd MMMM yyyy", now));
}
}, now);
frag.show(ft, "DateDialogFragment"); }
public interface DateDialogFragmentListener{
//this interface is a listener between the Date Dialog fragment and the activity to update the buttons date
public void updateChangedDate(int year, int month, int day);
}
public void addListenerOnSpinnerItemSelection() {
Locationspinner = (Spinner) findViewById(R.id.Locationspinner);
Locationspinner
.setOnItemSelectedListener(new CustomOnItemSelectedListener(
this));
}
protected void showCurrentLocation() {
// TODO Auto-generated method stub
// This is called to find current location based on GPS data and sends
// these values to the LongCoord and LatCoord TextViews
Location location = lm
.getLastKnownLocation(LocationManager.GPS_PROVIDER);
latitude = location.getLatitude();
longitude = location.getLongitude();
LongCoord.setText(Double.toString(longitude));
LatCoord.setText(Double.toString(latitude));
}
@Override
public void onClick(View arg0) {
Button b = (Button) findViewById(R.id.CalculateSunriseSunset);
b.setClickable(false);
new LongRunningGetIO().execute();
}
public class LongRunningGetIO extends AsyncTask<Void, Void, String> {
//Reads in the web service
protected String getASCIIContentFromEntity(HttpEntity entity)
throws IllegalStateException, IOException {
InputStream in = entity.getContent();
StringBuffer out = new StringBuffer();
int n = 1;
while (n > 0) {
byte[] b = new byte[4096];
n = in.read(b);
if (n > 0)
out.append(new String(b, 0, n));
}
return out.toString();
}
@SuppressLint("SimpleDateFormat")
@Override
protected String doInBackground(Void... params) {
HttpClient httpClient = new DefaultHttpClient();
HttpContext localContext = new BasicHttpContext();
// Finds todays date and adds that into the URL in simple date format DD/MM
SimpleDateFormat df = new SimpleDateFormat("dd/MM");
String formattedDate = df.format(now.getTime());
String finalURL = "http://www.earthtools.org/sun/"
+ LatCoord.getText().toString().trim() + "/"
+ LongCoord.getText().toString().trim() + "/"
+ formattedDate + "/99/0";
HttpGet httpGet = new HttpGet(finalURL);
String text = null;
try {
HttpResponse response = httpClient.execute(httpGet,
localContext);
HttpEntity entity = response.getEntity();
text = getASCIIContentFromEntity(entity);
} catch (Exception e) {
return e.getLocalizedMessage();
}
return text;
}
protected void onPostExecute(String results) {
if (results != null) {
try {
DocumentBuilderFactory dbFactory = DocumentBuilderFactory
.newInstance();
DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
InputSource s = new InputSource(new StringReader(results));
Document doc = dBuilder.parse(s);
doc.getDocumentElement().normalize();
TextView tvSunrise = (TextView) findViewById(R.id.Sunrise);
TextView tvSunset = (TextView) findViewById(R.id.Sunset);
tvSunrise.setText(doc.getElementsByTagName("sunrise").item(0).getTextContent());
tvSunset.setText(doc.getElementsByTagName("sunset").item(0).getTextContent());
} catch (Exception e) {
e.printStackTrace();
}
}
Button b = (Button) findViewById(R.id.CalculateSunriseSunset);
b.setClickable(true);
}
}
class MyLocationListener implements LocationListener {
@Override
public void onLocationChanged(Location location) {
// TODO Auto-generated method stub
}
@Override
public void onProviderDisabled(String provider) {
// TODO Auto-generated method stub
}
@Override
public void onProviderEnabled(String provider) {
// TODO Auto-generated method stub
}
@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
// TODO Auto-generated method stub
}
}
}
任何帮助都会非常感激:) x
答案 0 :(得分：3)
如果您还没有阅读，请阅读AsyncTask。
此类允许执行后台操作并发布结果 在UI线程上，无需操纵线程和/或处理程序。
您可以在其中使用的功能很少。例如： onPreExecute，doInBackground，onProgressUpdate和onPostExecute。
在onPreExecute（）上，使用以下内容声明一个对话框并显示一个loading ...框：
private final ProgressDialog dialog = new ProgressDialog(YourClass.this);
protected void onPreExecute() {
this.dialog.setMessage("loading...");
this.dialog.show();
}
然后在doInBackground中，您可以完成任务。即调用webservice并等待响应（这样你就可以在后台线程中等待而无需锁定UI）。
protected Boolean doInBackground(final Void unused) {
// call your web service here and do other stuff(wait).
// return true when success else false
}
上面的函数返回boolean，它被接受为onPostExecute中的参数 OnpostExecute（），停止对话框并显示其他事项，如成功等。如：
protected void onPostExecute(final Boolean result) {
if (this.dialog.isShowing()) { // if dialog box showing = true
this.dialog.dismiss(); // dismiss it
}
if (result.booleanValue()) {
//also show register success dialog
}
}
同时检查this个帖子。希望这可以帮助。
答案 1 :(得分：0)
在执行AsyncTask时尝试显示进度对话框，并在执行AsyncTask后关闭对话框。此外：
private ProgressDialog progressDialog;
@Override
public void onClick(View arg0) {
Button b = (Button) findViewById(R.id.CalculateSunriseSunset);
b.setClickable(false);
progressDialog = ProgressDialog.show(SunriseSunset.this, "Loading",
"Please wait while fetching data");
new LongRunningGetIO().execute();
}
...
protected void onPostExecute(String results) {
progressDialog.dismiss();
if (results != null) {
try {