我正在用google maps v2开发一个android应用程序，如果最近的加油站有没有汽油的话，我就可以找到它们的状态，现在我可以找到我的当前位置，在当前位置和给定的经纬度之间绘制路线，并在驾驶模式下获得到该位置的距离和持续时间。
我的问题是如何得到附近的加油站，是否有办法得到加油站的经度和纬度，因为我想执行的是得到距离最近的加油站，并有状态“有汽油在里面”，然后绘制到该位置的路线。
我想执行的场景是获取所有经纬度，并将它们存储到一个数据库中，数据库中有它们的状态，当用户去任何地方，它得到所有最近的加油站，然后去数据库中搜索状态，然后计算距离，然后画出附近加油站的“最短路径”，这是不是适合执行或者我可以用另一种方法来做，如果是的话，我该怎么做。
请查找我在下面使用的代码，我正在三星Galaxy S Duos S7562上进行测试
地图.java
package com.banzina;
public class Map extends Activity implements LocationListener{
GoogleMap map;
ArrayList<LatLng> markerPoints;
LatLng myposition;
LatLng position2;
float[] results = new float[1];
TextView tvDistanceDuration;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.show_map);
tvDistanceDuration = (TextView) findViewById(R.id.tv_dis);
MapFragment fm=(MapFragment) getFragmentManager().findFragmentById(R.id.map);
map=fm.getMap();
map.setMyLocationEnabled(true);
LocationManager locationManager=(LocationManager) getSystemService(LOCATION_SERVICE);
Criteria criteria=new Criteria(); // object to retrieve provider
String provider = locationManager.getBestProvider(criteria, true);
Location location=locationManager.getLastKnownLocation(provider);
if(location!=null){
onLocationChanged(location);
}
locationManager.requestLocationUpdates(provider, 20000, 0, this);
markerPoints = new ArrayList<LatLng>();
map = fm.getMap();
map.setMyLocationEnabled(true);
map.setOnMapClickListener(new OnMapClickListener() {
@Override
public void onMapClick(LatLng point){
if(markerPoints.size()>1) {
markerPoints.clear();
map.clear();
}
markerPoints.add(point);
MarkerOptions options = new MarkerOptions();
options.position(point);
if(markerPoints.size()==1) { options.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_GREEN));
}
else if(markerPoints.size()==2) { options.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_RED));
}
map.addMarker(options);
position2 = new LatLng(30.08393, 31.24225);
if(markerPoints.size() >= 2)
{
LatLng origin = markerPoints.get(0);
LatLng dest = markerPoints.get(1);
String url = getDirectionsUrl(myposition, position2);
DownloadTask downloadTask = new DownloadTask();
downloadTask.execute(url);
Location.distanceBetween(myposition.latitude, myposition.longitude, position2.latitude, position2.longitude, results);
map.addMarker(new MarkerOptions().position(position2).title("End"));
}
}
});
}
public void distanceTo (Location dest){}
public static void distanceBetween (double startLatitude, double startLongitude, double endLatitude, double endLongitude, float[] results){
}
public void onLocationChanged(Location location) {
double latitude = location.getLatitude();
double longitude = location.getLongitude();
LatLng latLng = new LatLng(latitude, longitude);
myposition = new LatLng(latitude, longitude);
map.addMarker(new MarkerOptions().position(myposition).title("Start"));
map.moveCamera(CameraUpdateFactory.newLatLng(latLng));
map.animateCamera(CameraUpdateFactory.zoomTo(17));
TextView t=(TextView) findViewById(R.id.tv_location);
t.setText("Latitude:" + latitude + ", Longitude:"+ longitude );
}
private String getDirectionsUrl(LatLng origin,LatLng dest){
String str_origin = "origin="+origin.latitude+","+origin.longitude;
String str_dest = "destination="+dest.latitude+","+dest.longitude;
String sensor = "sensor=false";
String parameters = str_origin+"&"+str_dest+"&"+sensor;
// Output format
String output = "json";
// Building the url to the web service
String url = "https://maps.googleapis.com/maps/api/directions/"+output+"?"+parameters;
return url;
}
/** A method to download json data from url */
private String downloadUrl(String strUrl) throws IOException{
String data = "";
InputStream iStream = null;
HttpURLConnection urlConnection = null;
try{
URL url = new URL(strUrl);
// Creating an http connection to communicate with url
urlConnection = (HttpURLConnection) url.openConnection();
// Connecting to url
urlConnection.connect();
// Reading data from url
iStream = urlConnection.getInputStream();
BufferedReader br = new BufferedReader(new InputStreamReader(iStream));
StringBuffer sb = new StringBuffer();
String line = "";
while( ( line = br.readLine()) != null){
sb.append(line);
}
data = sb.toString();
br.close();
}catch(Exception e){
Log.d("Exception while downloading url", e.toString());
}finally{
iStream.close();
urlConnection.disconnect();
}
return data;
}
// Fetches data from url passed
private class DownloadTask extends AsyncTask<String, Void, String>{
// Downloading data in non-ui thread
@Override
protected String doInBackground(String... url) {
// For storing data from web service
String data = "";
try{
// Fetching the data from web service
data = downloadUrl(url[0]);
}catch(Exception e){
Log.d("Background Task",e.toString());
}
return data;
}
// Executes in UI thread, after the execution of
// doInBackground()
@Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
ParserTask parserTask = new ParserTask();
// Invokes the thread for parsing the JSON data
parserTask.execute(result);
}
}
/** A class to parse the Google Places in JSON format */
private class ParserTask extends AsyncTask<String, Integer, List<List<HashMap<String,String>>> >{
// Parsing the data in non-ui thread
@Override
protected List<List<HashMap<String, String>>> doInBackground(String... jsonData) {
JSONObject jObject;
List<List<HashMap<String, String>>> routes = null;
try{
jObject = new JSONObject(jsonData[0]);
DirectionsJSONParser parser = new DirectionsJSONParser();
// Starts parsing data
routes = parser.parse(jObject);
}catch(Exception e){
e.printStackTrace();
}
return routes;
}
// Executes in UI thread, after the parsing process
@Override
protected void onPostExecute(List<List<HashMap<String, String>>> result) {
ArrayList<LatLng> points = null;
PolylineOptions lineOptions = null;
MarkerOptions markerOptions = new MarkerOptions();
String distance = "";
String duration = "";
// Traversing through all the routes
for(int i=0;i<result.size();i++){
points = new ArrayList<LatLng>();
lineOptions = new PolylineOptions();
// Fetching i-th route
List<HashMap<String, String>> path = result.get(i);
// Fetching all the points in i-th route
for(int j=0;j<path.size();j++){
HashMap<String,String> point = path.get(j);
if(j==0){ // Get distance from the list
distance = (String)point.get("distance");
continue;
}else if(j==1){ // Get duration from the list
duration = (String)point.get("duration");
continue;
}
double lat = Double.parseDouble(point.get("lat"));
double lng = Double.parseDouble(point.get("lng"));
LatLng position = new LatLng(lat, lng);
points.add(position);
}
// Adding all the points in the route to LineOptions
lineOptions.addAll(points);
lineOptions.width(2);
lineOptions.color(Color.RED);
}
tvDistanceDuration.setText("Distance:"+distance + ", Duration:"+duration);
// Drawing polyline in the Google Map for the i-th route
map.addPolyline(lineOptions);
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.map, menu);
return true;
}}
布局shou-map.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".ShowMap" >
<fragment
android:id="@+id/map"
android:layout_width="match_parent"
android:layout_height="match_parent"
class="com.google.android.gms.maps.MapFragment" />
<TextView
android:id="@+id/tv_location"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/map"
android:layout_alignTop="@+id/map"
android:layout_marginLeft="83dp"
android:text="TextView" />
<TextView
android:id="@+id/tv_dis"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_alignParentLeft="true"
android:layout_marginBottom="15dp"
android:layout_marginLeft="14dp"
android:text="TextView" />
</RelativeLayout>
清单.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.banzina"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="15"
android:targetSdkVersion="15" />
<permission
android:name="com.banzina.permission.MAPS_RECEIVE"
android:protectionLevel="signature" />
<uses-feature
android:glEsVersion="0x00020000"
android:required="true" />
<uses-permission android:name="com.banzina.permission.MAPS_RECEIVE" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="com.google.android.providers.gsf.permission.READ_GSERVICES" />
<uses-permission android:name="android.permission.com.google.android.providers.gsf.permission.READ_GSERVICES" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-feature
android:name="android.hardware.location"
android:required="false" />
<uses-feature
android:name="android.hardware.location.network"
android:required="false" />
<uses-feature android:name="android.hardware.location.gps" />
<uses-feature
android:name="android.hardware.wifi"
android:required="false" />
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name="com.banzina.Map"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<meta-data
android:name="com.google.android.maps.v2.API_KEY"
android:value="*********My Key********" />
</application>
</manifest>
目录jsonparser.java
package com.banzina;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import com.google.android.gms.maps.model.LatLng;
public class DirectionsJSONParser {
/** Receives a JSONObject and returns a list of lists containing latitude and longitude */
public List<List<HashMap<String,String>>> parse(JSONObject jObject){
List<List<HashMap<String, String>>> routes = new ArrayList<List<HashMap<String,String>>>() ;
JSONArray jRoutes = null;
JSONArray jLegs = null;
JSONArray jSteps = null;
JSONObject jDistance = null;
JSONObject jDuration = null;
try {
jRoutes = jObject.getJSONArray("routes");
/** Traversing all routes */
for(int i=0;i<jRoutes.length();i++){
jLegs = ( (JSONObject)jRoutes.get(i)).getJSONArray("legs");
List path = new ArrayList<HashMap<String, String>>();
/** Traversing all legs */
for(int j=0;j<jLegs.length();j++){
// jSteps = ( (JSONObject)jLegs.get(j)).getJSONArray("steps");
/** Getting distance from the json data */
jDistance = ((JSONObject) jLegs.get(j)).getJSONObject("distance");
HashMap<String, String> hmDistance = new HashMap<String, String>();
hmDistance.put("distance", jDistance.getString("text"));
/** Getting duration from the json data */
jDuration = ((JSONObject) jLegs.get(j)).getJSONObject("duration");
HashMap<String, String> hmDuration = new HashMap<String, String>();
hmDuration.put("duration", jDuration.getString("text"));
/** Adding distance object to the path */
path.add(hmDistance);
/** Adding duration object to the path */
path.add(hmDuration);
jSteps = ( (JSONObject)jLegs.get(j)).getJSONArray("steps");
/** Traversing all steps */
for(int k=0;k<jSteps.length();k++){
String polyline = "";
polyline = (String)((JSONObject)((JSONObject)jSteps.get(k)).get("polyline")).get("points");
List<LatLng> list = decodePoly(polyline);
/** Traversing all points */
for(int l=0;l<list.size();l++){
HashMap<String, String> hm = new HashMap<String, String>();
hm.put("lat", Double.toString(((LatLng)list.get(l)).latitude) );
hm.put("lng", Double.toString(((LatLng)list.get(l)).longitude) );
path.add(hm);
}
}
routes.add(path);
}
}
} catch (JSONException e) {
e.printStackTrace();
}catch (Exception e){
}
return routes;
}
/**
* Method to decode polyline points
* Courtesy : jeffreysambells.com/2010/05/27/decoding-polylines-from-google-maps-direction-api-with-java
* */
private List<LatLng> decodePoly(String encoded) {
List<LatLng> poly = new ArrayList<LatLng>();
int index = 0, len = encoded.length();
int lat = 0, lng = 0;
while (index < len) {
int b, shift = 0, result = 0;
do {
b = encoded.charAt(index++) - 63;
result |= (b & 0x1f) << shift;
shift += 5;
} while (b >= 0x20);
int dlat = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
lat += dlat;
shift = 0;
result = 0;
do {
b = encoded.charAt(index++) - 63;
result |= (b & 0x1f) << shift;
shift += 5;
} while (b >= 0x20);
int dlng = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
lng += dlng;
LatLng p = new LatLng((((double) lat / 1E5)),
(((double) lng / 1E5)));
poly.add(p);
}
return poly;
}
}
最佳答案
对于您的应用程序，您将需要访问包含位置的数据库，例如google places或yelp。
这个过程与解析方向的过程相同。通过向格式正确的url发送http get请求来查询api，下载返回的数据（很可能是json格式），解析它，然后添加Markers。
链接到我提到的api文档
https://developers.google.com/places/documentation/
http://www.yelp.com/developers/documentation/v2/overview