創建一個外部類來繪製Android上的路線

Question

我想在Android上的兩點之間繪製一條路線。我已經找到了如何在主要活動中使用它（我使用在stackoverflow上找到的DirectionsJSONParser類）。

但是，我想繪製很多路線，所以如果我要創建其他課程會更好。

我的夢想是有這樣的MainActivity：

public class MainActivity extends Activity { 

GoogleMap map; 
LatLng origin1; 
LatLng origin2; 
LatLng destination1; 
LatLng destination2; 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 

    // definition of origin1, origin2, destination1, destination2 

    ... 

    // here the call to the missing class ClassDrawingPath 
    PolylineOptions path1 = new ClassDrawingPath (origin1,destination1); 
    PolylineOptions path2 = new ClassDrawingPath (origin2,destination2); 

    gMap.addPolyline(path1); 
    gMap.addPolyline(path2); 

} 

} 

我複製源文件MainActity和DirectionsJSONParser，但你知道我不想顏色標記相同的活動，我只是想獲得一個「PolylineOptions」返回。

package example; 

import java.io.BufferedReader; 
import java.io.IOException; 
import java.io.InputStream; 
import java.io.InputStreamReader; 
import java.net.HttpURLConnection; 
import java.net.URL; 
import java.util.ArrayList; 
import java.util.HashMap; 
import java.util.List; 

import org.json.JSONObject; 

import android.graphics.Color; 
import android.os.AsyncTask; 
import android.os.Bundle; 
import android.support.v4.app.FragmentActivity; 
import android.util.Log; 
import android.view.Menu; 

import com.google.android.gms.maps.GoogleMap; 
import com.google.android.gms.maps.GoogleMap.OnMapClickListener; 
import com.google.android.gms.maps.SupportMapFragment; 
import com.google.android.gms.maps.model.BitmapDescriptorFactory; 
import com.google.android.gms.maps.model.LatLng; 
import com.google.android.gms.maps.model.MarkerOptions; 
import com.google.android.gms.maps.model.PolylineOptions; 


public class MainActivity extends FragmentActivity { 

    GoogleMap gMap; 
    ArrayList<LatLng> markerPoints; 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 

     // Initializing 
     markerPoints = new ArrayList<LatLng>(); 

     // Getting reference to SupportMapFragment of the activity_main 
     SupportMapFragment fm = (SupportMapFragment)getSupportFragmentManager().findFragmentById(R.id.map); 

     // Getting Map for the SupportMapFragment 
     map = fm.getMap();  

     if(map!=null){ 

      // Enable MyLocation Button in the Map 
      map.setMyLocationEnabled(true);  

      // Setting onclick event listener for the map 
      map.setOnMapClickListener(new OnMapClickListener() { 

       @Override 
       public void onMapClick(LatLng point) { 

        // Already two locations     
        if(markerPoints.size()>1){ 
         markerPoints.clear(); 
         map.clear();      
        } 

        // Adding new item to the ArrayList 
        markerPoints.add(point);     

        // Creating MarkerOptions 
        MarkerOptions options = new MarkerOptions(); 

        // Setting the position of the marker 
        options.position(point); 

        /** 
        * For the start location, the color of marker is GREEN and 
        * for the end location, the color of marker is RED. 
        */ 
        if(markerPoints.size()==1){ 
         options.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_GREEN)); 
        }else if(markerPoints.size()==2){ 
         options.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_RED)); 
        } 


        // Add new marker to the Google Map Android API V2 
        map.addMarker(options); 

        // Checks, whether start and end locations are captured 
        if(markerPoints.size() >= 2){     
         LatLng origin = markerPoints.get(0); 
         LatLng dest = markerPoints.get(1); 

         // Getting URL to the Google Directions API 
         String url = getDirectionsUrl(origin, dest);     

         DownloadTask downloadTask = new DownloadTask(); 

         // Start downloading json data from Google Directions API 
         downloadTask.execute(url); 
        } 

       } 
      }); 
     }  
    } 

    private String getDirectionsUrl(LatLng origin,LatLng dest){ 

     // Origin of route 
     String str_origin = "origin="+origin.latitude+","+origin.longitude; 

     // Destination of route 
     String str_dest = "destination="+dest.latitude+","+dest.longitude;  


     // Sensor enabled 
     String sensor = "sensor=false";   

     // Building the parameters to the web service 
     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(); 

      // 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);     

        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); 

      } 

      // 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.main, menu); 
     return true; 
    } 
} 

而且

package example; 

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;  

     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"); 

        /** 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 : http://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; 
    } 
} 

感謝您的幫助:)

Answer 1

我跟着this answer創建一個類來繪製的方向。 有一點自定義它真的很有用。我設法在地圖上畫一條折線，並得到方向列表。