java - 如何使用带有 json 的 Map 从数据库设置 map latlng 值？

Question

我尝试使用 json 从数据库设置纬度和经度值来解析从 php 返回的响应在函数 setmMap 中，我解析 json 并且 woking 会!我单独测试了它并工作了! 在mapReady上我调用setmMap()并使用log来测试日志打印map1和map2而不是打印map3这意味着不进入forloop如何让它进入谢谢

{package com.example.lef.firstapplication;
import android.graphics.Color;
import android.graphics.Typeface;
import android.location.Geocoder;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.util.Log;
import android.view.Gravity;
import android.view.View;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.TextView;
import android.widget.Toast;
import com.android.volley.Request;
import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.StringRequest;
import com.android.volley.toolbox.Volley;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.OnMapReadyCallback;
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.Marker;
import com.google.android.gms.maps.model.MarkerOptions;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.util.ArrayList;
import java.util.List;
import java.util.Locale;

   public class MapsActivity extends FragmentActivity implements 
   OnMapReadyCallback,GoogleMap.OnMarkerClickListener {

private GoogleMap mMap;

private static final LatLng PERTH = new LatLng(-31.952854, 115.857342);
private static final LatLng SYDNEY = new LatLng(-33.87365, 151.20689);
private static final LatLng BRISBANE = new LatLng(-27.47093, 153.0235);

private Marker mPerth;
private Marker mSydney;
private Marker mBrisbane;

RequestQueue requestQueue;
String allFriend = "http://192.168.0.103/PlaneEye/v1/allFriend";

int friend_id;
String friend_Fname;
String friend_Lname;
double latitude;
double longitude;

LinearLayout info ;
TextView title ;
Button button;
TextView snippet;
public List <User> userInf=new ArrayList<>();
public List <User> friendList=new ArrayList<>();

public List<User> getUserInf() {
    return userInf;
}

public void setUserInf(List<User> userInf) {
    this.userInf = userInf;
}

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_maps);
    info = new LinearLayout(this);
    title = new TextView(this);
    snippet = new TextView(this);
    button = new Button(this);
   // prepareFriendsLocation();
    info.setGravity(Gravity.CENTER_HORIZONTAL|Gravity.CENTER_VERTICAL);
    button.setBackgroundColor(Color.WHITE);
    SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
            .findFragmentById(R.id.map);
    mapFragment.getMapAsync(this);
    prepareFriendsList();

}


public void setmMap()
{
    Log.w("test","map1");
    friendList=prepareFriendsList();
    Log.w("test","map2");
    for (int i=0;i<friendList.size();i++)
    { Log.w("test","map3");
        mMap.addMarker(new MarkerOptions()
                .position(new LatLng(friendList.get(i).getLatitude(),friendList.get(i).getLongitude()))
                .title(friendList.get(i).getfName()+friendList.get(i).getlName())
                .snippet("(-27.47093,153.0235)")
                .icon(BitmapDescriptorFactory.fromResource(R.drawable.friends_on_map))).setTag(0);
        Log.w("jk",friendList.get(i).getfName()+friendList.get(i).getlName()+"yarb b2a");
    }
    mMap.setOnMarkerClickListener(this);
    //getCompleteAddressString(-27.47093,153.0235);
    //change markerInfoWindow style
    mMap.setInfoWindowAdapter(new GoogleMap.InfoWindowAdapter() {
        @Override
        public View getInfoWindow(Marker arg0) {
            return null;
        }
        @Override
        public View getInfoContents(Marker marker) {
            info.setOrientation(LinearLayout.VERTICAL);
            title.setTextColor(Color.BLACK);
            title.setGravity(Gravity.CENTER);
            title.setTypeface(null, Typeface.BOLD);
            title.setText(marker.getTitle());
            button.setText("Send Message");
            snippet.setTextColor(Color.GRAY);
            snippet.setText(marker.getSnippet());
            info.removeView(title);
            info.addView(title);
            info.removeView(snippet);
            info.addView(snippet);
            info.removeView(button);
            info.addView(button);
            return info;
        }
    });
}


private List prepareFriendsList() {
    requestQueue = Volley.newRequestQueue(this);
    StringRequest request=new StringRequest(Request.Method.POST, "http://192.168.0.103/PlaneEye/v1/allFriend", new Response.Listener<String>() {
        @Override
        public void onResponse(String response) {
            try {
                JSONObject user = new JSONObject(response);
                JSONArray friends=user.getJSONArray("users");
                for (int i = 0; i <friends.length() ; i++) {
                    final JSONObject friend = friends.getJSONObject(i);
                    friend_id      = friend.getInt("user_id");
                    friend_Fname = friend.getString("fName");
                    friend_Lname = friend.getString("lName");

                    latitude    = friend.getDouble("latitude");
                    longitude   = friend.getDouble("longitude");
                    int online = friend.getInt("online");
                    userInf.add(new User(friend_id,friend_Fname,friend_Lname,latitude,longitude,online));
                    setUserInf(userInf);
                }

            } catch (JSONException e) {

            }
        }
    }, new Response.ErrorListener() {
        @Override
        public void onErrorResponse(VolleyError error) {
            Log.d("userData", "Error");
        }
    });
    requestQueue.add(request);
    return getUserInf();
}
@Override
public void onMapReady(GoogleMap map) {
    mMap = map;
    // Add  markers to the map


    setmMap();

}
@Override
//CLick setOnMarkerClickListener
public boolean onMarkerClick(final Marker marker) {
    // Retrieve the data from the marker.
    Integer clickCount = (Integer) marker.getTag();
    // Check if a click count was set, then display the click count.
    if (clickCount != null) {
        clickCount = clickCount + 1;
        marker.setTag(clickCount);
        Toast.makeText(this,
                marker.getTitle() +
                        " has been clicked " + clickCount + " times.",
                Toast.LENGTH_SHORT).show();
    }
    return false;
}
//get the location from lattude logtude
private String getCompleteAddressString(double LATITUDE, double LONGITUDE) 
 {
    String strAdd = "";
    Geocoder geocoder = new Geocoder(this, Locale.getDefault());
        try {
            List<android.location.Address> addresses = 
            geocoder.getFromLocation(LATITUDE, LONGITUDE, 1);
            if(Geocoder.isPresent()) {
                if (addresses != null) {
                    android.location.Address returnedAddress =addresses.get(0);
                    StringBuilder strReturnedAddress = new StringBuilder("");
                    for (int i = 0; i <= returnedAddress.getMaxAddressLineIndex(); i++) {
                        strReturnedAddress.append(returnedAddress.getAddressLine(i)).append("\n");
                    }
                    strAdd = strReturnedAddress.toString();
                } else {
                    //strAdd = "unfortunately, we can't display address Now";
                }
            }
        else
        {
            Log.w("error","false");
        }
    }  
    catch (Exception e) {
        e.printStackTrace();
        //strAdd = "Please check your internet connection";
    }
    return strAdd;
}

Answer 1

这可以构造得更好，但这里有一个代码示例来帮助您开始。

private void prepareFriendsList() {
    requestQueue = Volley.newRequestQueue(this);
    StringRequest request=new StringRequest(Request.Method.POST,
            "http://192.168.0.103/PlaneEye/v1/allFriend",
            new Response.Listener<String>() {
                @Override
                public void onResponse(String response) {
                    try {
                        List<User> users = new ArrayList<>();
                        JSONObject user = new JSONObject(response);


                        JSONArray friends=user.getJSONArray("users");
                        for (int i = 0; i <friends.length() ; i++) {
                            final JSONObject friend = friends.getJSONObject(i);
                            friend_id      = friend.getInt("user_id");
                            friend_Fname = friend.getString("fName");
                            friend_Lname = friend.getString("lName");

                            latitude    = friend.getDouble("latitude");
                            longitude   = friend.getDouble("longitude");
                            int online = friend.getInt("online");
                            users.add(new User(friend_id,friend_Fname,friend_Lname,latitude,longitude,online));
                            //setUserInf(userInf); // Dont update the entire list every iteration.
                        }
                        Log.d("Users parsed, call back to set Users!");
                        setUserInf(users);

                    } catch (JSONException e) {

                    }
                }
            }, 
            new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {
                    Log.d("userData", "Error");
            }
    });
    requestQueue.add(request);
    Log.d("Request Sent!");
    //return getUserInf(); // empty list since users not parsed yet 
}

然后更改 setUserInf，这是异步响应准备就绪时的回调。使用此函数来构建 map 对象。

public void setUserInf(List<User> users) {
    this.userInf = users;
    Log.d("Response callback!!"); 
    for (int i=0;i<friendList.size();i++){ 

       mMap.addMarker(new MarkerOptions() ...
    }
    ...   
}

这将为您提供预期的流程。

> Request Sent!
> //... other logs while waiting for response. 
> Users parsed, call back to set Users!
> Response callback!!