在 Android 应用程序中将 geojson 文件添加到我的地图

Posted 2023-04-14

【中文标题】在 Android 应用程序中将 geojson 文件添加到我的地图

【英文标题】：Add a geojson file to my Map in Android App

【发布时间】：2019-06-04 01:55:51

【问题描述】：

我对 android Studio 和 Java 非常陌生。我尝试制作一个带有一些兴趣点的地图应用程序。这些点是一个geojson文件。我阅读了 google 的示例及其网站 (Google Maps Android GeoJSON Utility) 中的说明，但我的代码中有一些错误。第一个错误与 getmMap 方法有关，（错误：找不到符号方法 getnMap()）。我找到解决方案的第二个是关于文件它不需要扩展名（geojson）。我在 rs 中创建了一个名为 raw 的文件夹，并在其中添加了 geojson 文件。

MapsActivity.java的完整代码

package com.example.vassilis.goldman_find_atm;

import android.Manifest;
import android.content.pm.PackageManager;
import android.os.Build;
import android.support.v4.app.ActivityCompat;
import android.support.v4.app.FragmentActivity;
import android.os.Bundle;

import com.google.android.gms.maps.CameraUpdateFactory;
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.LatLng;
import com.google.android.gms.maps.model.MarkerOptions;
import com.google.maps.android.data.geojson.GeoJsonLayer;

public class MapsActivity extends FragmentActivity implements OnMapReadyCallback 

    private static final int MY_REQUEST_INT = 177;
    private GoogleMap mMap;

    @Override
    protected void onCreate(Bundle savedInstanceState) 
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_maps);
        // Obtain the SupportMapFragment and get notified when the map is ready to be used.
        SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
                .findFragmentById(R.id.map);
        mapFragment.getMapAsync(this);
    


    /**
     * Manipulates the map once available.
     * This callback is triggered when the map is ready to be used.
     * This is where we can add markers or lines, add listeners or move the camera. In this case,
     * we just add a marker near Sydney, Australia.
     * If Google Play services is not installed on the device, the user will be prompted to install
     * it inside the SupportMapFragment. This method will only be triggered once the user has
     * installed Google Play services and returned to the app.
     */
    @Override
    public void onMapReady(GoogleMap googleMap) 
        mMap = googleMap;

        //Enable Current Location:

        //Here We want to check the permission of Location - GPS
        if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) 
            // TODO: Consider calling

            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M)

                requestPermissions(new String[]Manifest.permission.ACCESS_COARSE_LOCATION,
                        Manifest.permission.ACCESS_FINE_LOCATION,MY_REQUEST_INT);
            

            return;
        else 
            //Here the code of Grand Permission
            mMap.setMyLocationEnabled(true);

        

        // Add a marker in Sydney and move the camera
        /*LatLng sydney = new LatLng(-34, 151);
        mMap.addMarker(new MarkerOptions().position(sydney).title("Marker in Sydney"));
        mMap.moveCamera(CameraUpdateFactory.newLatLng(sydney));*/


        GeoJsonLayer layer = new GeoJsonLayer(getmMap(), R.raw.nbg_bank.geojson ,
                getApplicationContext());
        layer.addLayerToMap();
    

错误：cnnot find symbol method getmMap()

我将 getmMap() 更改为 mMap 和系统 :Surround with try/catch。我更改它并将代码更改为。代码的构建完成没有问题，但在地图上我没有看到点。

来自

GeoJsonLayer layer = new GeoJsonLayer(mMap, R.raw.nbg_bank,
                getApplicationContext());

        layer.addLayerToMap();

收件人

GeoJsonLayer layer = null;
        try 
            layer = new GeoJsonLayer(mMap, R.raw.nbg_bank,
                    getApplicationContext());
         catch (IOException e) 
            e.printStackTrace();
         catch (JSONException e) 
            e.printStackTrace();
        

        layer.addLayerToMap();

【问题讨论】：

只需使用mMap 而不是getmMap()

我改变了，但我必须从 GeoJsonLayer layer = new GeoJsonLayer(mMap, R.raw.nbg_bank, getApplicationContext()); layer.addLayerToMap();到 GeoJsonLayer 层 = null;尝试 layer = new GeoJsonLayer(mMap, R.raw.nbg_bank, getApplicationContext()); catch (IOException e) e.printStackTrace(); catch (JSONException e) e.printStackTrace(); layer.addLayerToMap();然后鳕鱼建立了，但地图中没有点

【参考方案1】：

确保您的 json 文件格式正确。

检查此geojson 文件代码：

    "type": "FeatureCollection",
    "features": [

        "type": "Feature",
         "geometry": 
             "type": "Point",
             "coordinates": 
                [102.0, 0.5]
         ,
         "properties": 
         "prop0": "value0"
         
        , 

           "type": "Feature",
           "geometry": 
               "type": "LineString",
               "coordinates": [
                 [102.0, 0.0],
                 [103.0, 1.0],
                 [104.0, 0.0],
                 [102.0, 0.0]
                 ]
               ,
               "properties": 
                "prop0": "value0",
                "prop1": 0.0
               
        
    ]

更多信息请参考：https://cran.r-project.org/web/packages/geojsonR/vignettes/the_geojsonR_package.html

要检查您的 GeoJson 文件是否正确，请访问：http://geojsonlint.com/