Google地图通过Android中的HTTPS反向地理编码 [英] Google maps reverse geocoding via HTTPS in Android
问题描述
我正在制作谷歌地图应用程序。由于Geocoder类返回空（在[0]越界）我目前正在尝试HTTPS谷歌地图反向地理编码。
这是我的onClick调用：
public JSONArray getAddress（LatLng latLng）throws IOException {
URL url =新网址（https://maps.googleapis.com/maps/api/geocode/json?latlng=+ latLng.latitude +，+ latLng.longitude +& key = AIza ******* ****************）;
Async async = new Async（）;
async.execute（url）;
JSONArray response = async.jsonArray;
返回响应;
$ b 这是Async子类：
public class Async extends AsyncTask< URL，Void，JSONArray> {
public JSONArray jsonArray;
@Override
protected JSONArray doInBackground（URL ... params）{
BufferedReader reader;
InputStream是;
尝试{
StringBuilder responseBuilder = new StringBuilder（）;
HttpURLConnection conn =（HttpURLConnection）params [0] .openConnection（）;
conn.setReadTimeout（10000）;
conn.setConnectTimeout（15000）;
conn.setRequestMethod（GET）;
conn.setDoInput（true）;
conn.connect（）;
is = conn.getInputStream（）;
reader = new BufferedReader（new InputStreamReader（is））;
for（String line;（line = reader.readLine（））！= null;）{
responseBuilder.append（line）.append（\\\
）;
}
jsonArray = new JSONArray（responseBuilder.toString（））;
} catch（MalformedURLException e）{
e.printStackTrace（）;
} catch（ProtocolException e）{
e.printStackTrace（）;
} catch（IOException e）{
e.printStackTrace（）;
} catch（JSONException e）{
e.printStackTrace（）;
}
return jsonArray;
}
和manifest.xml：
< uses-permission android：name =android.permission.ACCESS_COARSE_LOCATION/>
< uses-permission android：name =android.permission.ACCESS_FINE_LOCATION/>
< uses-permission android：name =android.permission.INTERNET/>
< uses-permission android：name =android.permission.WRITE_EXTERNAL_STORAGE/>
< uses-permission android：name =android.permission.ACCESS_NETWORK_STATE/>
Onclick方法：
@Override
public void onMapClick（LatLng latLng）{
JSONArray js = null;
尝试{
js = getAddress（latLng）;
mMap.addMarker（new MarkerOptions（）。position（latLng）.title（js.getString（0））。draggable（true））; // NullPointer
} catch（IOException e）{
e.printStackTrace（）;
} catch（JSONException p）{
// todo
}
4天后，我试图获得与NullPointerException不同的内容。任何想法我做错了什么？在以调试模式连接的平板电脑上测试。
任何帮助都会有用。我非常绝望。
解决方案由于AsyncTask是Activity的子类，因此您只需将LatLng分配给Activity的成员变量它可以在AsyncTask中访问。
然后，将标记添加到onPostExecute（）。
首先，更改为活动代码。
除JSONArray之外，还创建一个LatLng成员变量：
public class MyMapActivity extends AppCompatActivity implements OnMapReadyCallback
{
JSONArray js;
LatLng currLatLng;
// ...............
然后，修改onMapClick以将LatLng分配给实例变量：
@Override
public void onMapClick（LatLng latLng ）{
JSONArray js = null;
尝试{
//分配给成员变量：
currLatLng = latLng;
//不使用返回值：
getAddress（latLng）;
//删除：
//mMap.addMarker（new MarkerOptions（）。position（latLng）.title（js.getString（0））。draggable（true））; / NullPointer
} catch（IOException e）{
e.printStackTrace（）;
} catch（JSONException p）{
// todo
}
然后，在获得响应后，使用onPostExecute放置标记。
另一个主要问题是JSON响应是一个包含JSONArray的JSONObject。
在以下代码中修复：
$ pre code> public class Async extends AsyncTask< URL，Void，JSONArray> {
public JSONArray jsonArray;
@Override
protected JSONArray doInBackground（URL ... params）{
BufferedReader reader;
InputStream是;
尝试{
StringBuilder responseBuilder = new StringBuilder（）;
HttpURLConnection conn =（HttpURLConnection）params [0] .openConnection（）;
conn.setReadTimeout（10000）;
conn.setConnectTimeout（15000）;
conn.setRequestMethod（GET）;
conn.setDoInput（true）;
conn.connect（）;
is = conn.getInputStream（）;
reader = new BufferedReader（new InputStreamReader（is））;
for（String line;（line = reader.readLine（））！= null;）{
responseBuilder.append（line）.append（\\\
）;
}
JSONObject jObj = new JSONObject（responseBuilder.toString（））;
jsonArray = jObj.getJSONArray（results）;
} catch（MalformedURLException e）{
e.printStackTrace（）;
} catch（ProtocolException e）{
e.printStackTrace（）;
} catch（IOException e）{
e.printStackTrace（）;
} catch（JSONException e）{
e.printStackTrace（）;
}
return jsonArray;
@Override
protected void onPostExecute（JSONArray jsonArrayResponse）{
js = jsonArrayResponse;
尝试{
if（js！= null）{
JSONObject jsFirstAddress = js.getJSONObject（0）;
mMap.addMarker（new MarkerOptions（）。position（currLatLng）.title（jsFirstAddress.getString（formatted_address））。draggable（true））;
}
} catch（JSONException e）{
e.printStackTrace（）;
}
}
}
请注意，需要从getAddress（）返回任何东西，所以只需要返回类型 void ，然后让AsyncTask执行其余部分：
public void getAddress（LatLng latLng）throws IOException {
URL url = new URL（https://maps.googleapis.com/maps/api/geocode /json?latlng=\"+latLng.latitude+\",\"+latLng.longitude+\"&key=AIza***********************）;
Async async = new Async（）;
async.execute（url）;
// JSONArray response = async.jsonArray;
//返回响应;
}
I am making google map app. Since Geocoder class returns empty(out of bounds at [0]) i am currently trying the HTTPS Google maps reverse GeoCoding. This is my onClick call:
public JSONArray getAddress(LatLng latLng) throws IOException {
URL url = new URL("https://maps.googleapis.com/maps/api/geocode/json?latlng="+latLng.latitude+","+latLng.longitude+"&key=AIza***********************");
Async async =new Async();
async.execute(url);
JSONArray response = async.jsonArray;
return response;
}
This is the Async subclass:
public class Async extends AsyncTask<URL, Void, JSONArray> {
public JSONArray jsonArray;
@Override
protected JSONArray doInBackground(URL... params) {
BufferedReader reader;
InputStream is;
try {
StringBuilder responseBuilder = new StringBuilder();
HttpURLConnection conn = (HttpURLConnection) params[0].openConnection();
conn.setReadTimeout(10000);
conn.setConnectTimeout(15000);
conn.setRequestMethod("GET");
conn.setDoInput(true);
conn.connect();
is = conn.getInputStream();
reader = new BufferedReader(new InputStreamReader(is));
for (String line; (line = reader.readLine()) != null; ) {
responseBuilder.append(line).append("\n");
}
jsonArray = new JSONArray(responseBuilder.toString());
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (ProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (JSONException e) {
e.printStackTrace();
}
return jsonArray;
}
and manifest.xml:
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
Onclick method :
@Override
public void onMapClick(LatLng latLng) {
JSONArray js=null;
try {
js = getAddress(latLng);
mMap.addMarker(new MarkerOptions().position(latLng).title(js.getString(0)).draggable(true));//NullPointer
} catch (IOException e) {
e.printStackTrace();
} catch (JSONException p) {
//todo
}
For 4 days now i am trying to get something different than NullPointerException. Any idea what am i doing wrong? Tested on tablet connected in debug mode. Any help will be useful. I am quite desperate.
Since the AsyncTask is a subclass of the Activity, you just need to assign the LatLng to a member variable of the Activity so that it's accessible in the AsyncTask.
Then, add the Marker in onPostExecute().
First, the change to the Activity code. Make a LatLng member variable in addition to the JSONArray:
public class MyMapActivity extends AppCompatActivity implements OnMapReadyCallback
{
JSONArray js;
LatLng currLatLng;
//...............
Then, modify the onMapClick to assign the LatLng to the instance variable:
@Override
public void onMapClick(LatLng latLng) {
JSONArray js=null;
try {
//assign to member variable:
currLatLng = latLng;
//don't use the return value:
getAddress(latLng);
//remove this:
//mMap.addMarker(new MarkerOptions().position(latLng).title(js.getString(0)).draggable(true));//NullPointer
} catch (IOException e) {
e.printStackTrace();
} catch (JSONException p) {
//todo
}
Then, use onPostExecute to place the marker after you have the response. The other main issue is that the JSON response is a JSONObject that contains a JSONArray inside it. Fixed in the code below:
public class Async extends AsyncTask<URL, Void, JSONArray> {
public JSONArray jsonArray;
@Override
protected JSONArray doInBackground(URL... params) {
BufferedReader reader;
InputStream is;
try {
StringBuilder responseBuilder = new StringBuilder();
HttpURLConnection conn = (HttpURLConnection) params[0].openConnection();
conn.setReadTimeout(10000);
conn.setConnectTimeout(15000);
conn.setRequestMethod("GET");
conn.setDoInput(true);
conn.connect();
is = conn.getInputStream();
reader = new BufferedReader(new InputStreamReader(is));
for (String line; (line = reader.readLine()) != null; ) {
responseBuilder.append(line).append("\n");
}
JSONObject jObj= new JSONObject(responseBuilder.toString());
jsonArray = jObj.getJSONArray("results");
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (ProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (JSONException e) {
e.printStackTrace();
}
return jsonArray;
}
@Override
protected void onPostExecute(JSONArray jsonArrayResponse) {
js = jsonArrayResponse;
try {
if (js != null) {
JSONObject jsFirstAddress = js.getJSONObject(0);
mMap.addMarker(new MarkerOptions().position(currLatLng).title(jsFirstAddress.getString("formatted_address")).draggable(true));
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}
Note that you don't need to return anything from getAddress(), so just make the return type void and let the AsyncTask do the rest once it's executed:
public void getAddress(LatLng latLng) throws IOException {
URL url = new URL("https://maps.googleapis.com/maps/api/geocode/json?latlng="+latLng.latitude+","+latLng.longitude+"&key=AIza***********************");
Async async =new Async();
async.execute(url);
//JSONArray response = async.jsonArray;
//return response;
}
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