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我正在使用AsyncTask在mySQL在线数据库中运行信息。然后我使用JSON解析将数据库中的信息添加为MapBox地图上的标记。目前，当用户上传新标记（代码中的washroom）时，它会将信息上载到数据库，然后运行onPostExecute方法并返回到MapsActivity.java。 MapsActivity.java应重新加载地图并显示新添加的标记，但它不会;它只显示在添加新标记之前添加的标记。如果您关闭并打开应用程序，则会更新标记，并显示包括新标记在内的所有标记！任何帮助，将不胜感激！ MapsActivity.java的onPostExecute未正确启动活动
部分
public class MapsActivity extends FragmentActivity {
private MapView mapView;
private MapboxMap map;
private ImageButton locationToggle;
private LocationServices locationServices;
private String json_string;
private JSONObject jsonObject;
private JSONArray jsonArray;
public static String WASHROOMINFO;
public static String CURRENT_LOCATION;
private static final int PERMISSIONS_LOCATION = 0;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
MapboxAccountManager.start(this, getString(R.string.accessToken));
setContentView(R.layout.activity_maps);
//getting location services
locationServices = com.mapbox.mapboxsdk.location.LocationServices.getLocationServices(MapsActivity.this);
//onClick to go to add washroom activity
findViewById(R.id.addWashroom).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if (CURRENT_LOCATION != null) {
Intent intent = new Intent(getBaseContext(), AddWashroom.class);
startActivity(intent);
} else {
Toast.makeText(getBaseContext(),"You Must Turn on User Location Before Adding a Washroom!",Toast.LENGTH_LONG).show();
}
}
});
//washrooms have not been loaded in yet
if (!BackgroundTask.WASHROOMS_LOADED) {
//getting database info
String method = "getWashroom";
BackgroundTask backgroundTask = new BackgroundTask(getBaseContext());
backgroundTask.execute(method);
finish();
}
mapView = (MapView) findViewById(R.id.mapview);
mapView.onCreate(savedInstanceState);
mapView.getMapAsync(new OnMapReadyCallback() {
@Override
public void onMapReady(MapboxMap mapboxMap) {
//when map is ready assign mapboxMap variable
map = mapboxMap;
//Washroom loading has been requested and JSON data is ready
if (BackgroundTask.WASHROOMS_LOADED) {
//Getting JSON data from intent
json_string = getIntent().getExtras().getString("json_data");
try {
//new JSON object from JSON data
jsonObject = new JSONObject(json_string);
//gets JSON array from JSON object
jsonArray = jsonObject.getJSONArray("server_response");
//Marker list for buffering markers
List<Marker> markers = new ArrayList<Marker>();
//do this for all markers!
for (int i = 0; i < jsonArray.length(); i++) {
//Single JSON object of single marker
JSONObject JO = jsonArray.getJSONObject(i);
//Dividing location field into lat & lng
String latlng = JO.getString("location");
String[] latlngSplit = latlng.split(" , ",2);
double lat = Double.valueOf(latlngSplit[0]);
double lng = Double.valueOf(latlngSplit[1]);
//adding marker
Marker marker = map.addMarker(new MarkerOptions()
.title(JO.getString("name"))
.setSnippet(JO.getString("price"))
.position(new LatLng(lat,lng))
);
//add marker to markers list.
markers.add(marker);
}
BackgroundTask.WASHROOMS_LOADED = false;
} catch (JSONException e) {
e.printStackTrace();
}
}
}
});
locationToggle = (ImageButton) findViewById(R.id.location_toggle);
locationToggle.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (map != null) {
//toggle GPS when clicking show location button
toggleGps(!map.isMyLocationEnabled());
}
}
});
}
BackgroundTask（的AsyncTask）
class BackgroundTask extends AsyncTask<String, Void, String> {
Context ctx;
public static boolean WASHROOMS_LOADED;
private String JSON_STRING;
private String json_string;
BackgroundTask(Context ctx) {
this.ctx = ctx.getApplicationContext();
}
@Override
protected void onPreExecute() {
super.onPreExecute();
}
String add_url = "http://appart-software.com/add_washroom.php";
String get_url = "http://appart-software.com/get_washroom.php";
@Override
protected String doInBackground(String... params) {
String method = params[0];
if (method.equals("addWashroom")) {
String location = params[1];
String name = params[2];
String price = params[3];
try {
URL url = new URL(add_url);
HttpURLConnection httpUrlConnection = (HttpURLConnection) url.openConnection();
httpUrlConnection.setRequestMethod("POST");
httpUrlConnection.setDoOutput(true);
OutputStream outputStream = httpUrlConnection.getOutputStream();
BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(outputStream,"UTF-8"));
String data_string = URLEncoder.encode("WClocation","UTF-8")+"="+URLEncoder.encode(location,"UTF-8")+"&"+
URLEncoder.encode("WCname","UTF-8")+"="+URLEncoder.encode(name,"UTF-8")+"&"+
URLEncoder.encode("WCprice","UTF-8")+"="+URLEncoder.encode(price,"UTF-8");
bufferedWriter.write(data_string);
bufferedWriter.flush();
bufferedWriter.close();
outputStream.close();
InputStream inputStream = httpUrlConnection.getInputStream();
inputStream.close();
httpUrlConnection.disconnect();
return "Washroom Added!";
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
//You want to get washroom info
} else if (method.equals("getWashroom")){
try {
URL url = new URL(get_url);
HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
InputStream inputStream = httpURLConnection.getInputStream();
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream,"iso-8859-1"));
StringBuilder stringBuilder = new StringBuilder();
while ((JSON_STRING = bufferedReader.readLine())!=null) {
stringBuilder.append(JSON_STRING+"\n");
}
bufferedReader.close();
inputStream.close();
httpURLConnection.disconnect();
//Return JSON formatted info
return stringBuilder.toString().trim();
} catch (MalformedURLException e){
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
return null;
}
@Override
protected void onProgressUpdate(Void... values) {
super.onProgressUpdate(values);
}
@Override
protected void onPostExecute(String result) {
if (result.equals("Washroom Added!")) {
Toast.makeText(ctx,result,Toast.LENGTH_LONG).show();
WASHROOMS_LOADED = false;
} else {
//setting result as a movable string
json_string = result;
//intent and sending JSON data
Intent intent = new Intent(ctx,MapsActivity.class);
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
intent.putExtra("json_data",json_string);
ctx.startActivity(intent);
WASHROOMS_LOADED = true;
}
}
}
如果你不再需要我的代码，我会很乐意展示更多一些。
调查覆盖'onNewIntent'，否则意图数据不会更新。 – TWL
在你的'startActivity（）'中，你提供的'intent'基本上会创建一个你的'MapActivity'的新实例，因此，你会得到这个结果。你可以通过创建一个接口来解决这两个类，并使用它们进行交互。 – Shaishav