如何正確獲取天氣圖層？

Question

我想讓降雪天氣圖層出現在我的Google地圖活動中，但無法理解它爲什麼沒有顯示在地圖上。我在app\src\debug\res\values\google_maps_api.xml中實施了我的Google地圖密鑰，已經在Android SDK管理器中安裝了Google Play服務，並且我已經在OpenWeatherMap中爲其API（在下面列出）中創建了一個帳戶。

地圖加載正常，當我在帶有輸入縮放的單獨瀏覽器中搜索圖層時，x，y顯示正常，但我無法讓圖層出現在我的Google地圖活動中。

我需要定義x，y，縮放還是這些從URL中拉出來？

這是我的java：

package com.example.user.project; 

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.android.gms.maps.model.TileOverlay; 
import com.google.android.gms.maps.model.TileOverlayOptions; 
import com.google.android.gms.maps.model.TileProvider; 
import com.google.android.gms.maps.model.UrlTileProvider; 

import java.net.MalformedURLException; 
import java.net.URL; 
import java.util.Locale; 

public class MapsActivity extends FragmentActivity implements OnMapReadyCallback { 

    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; 

     // Move the camera 
     LatLng indy = new LatLng(39, -86.5); 
     mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(indy, 8)); 

     TileProvider tileProvider = new UrlTileProvider(256, 256) { 
      @Override 
      public URL getTileUrl(int x, int y, int zoom) { 

    /* Define the URL pattern for the tile images */ 
       String s = String.format(Locale.US, "http://tile.openweathermap.org/map/precipitation/%d/%d/%d.png?appid={my_key}", 
         zoom, x, y); 

       if (!checkTileExists(x, y, zoom)) { 
        return null; 
       } 

       try { 
        return new URL(s); 
       } catch (MalformedURLException e) { 
        throw new AssertionError(e); 
       } 
      } 

      /* 
      * Check that the tile server supports the requested x, y and zoom. 
      * Complete this stub according to the tile range you support. 
      * If you support a limited range of tiles at different zoom levels, then you 
      * need to define the supported x, y range at each zoom level. 
      */ 
      private boolean checkTileExists(int x, int y, int zoom) { 
       int minZoom = 12; 
       int maxZoom = 16; 

       return !(zoom < minZoom || zoom > maxZoom); 

      } 
     }; 

     TileOverlay tileOverlay = mMap.addTileOverlay(new TileOverlayOptions() 
       .tileProvider(tileProvider)); 
    } 
} 

下面是Android Studio生成佈局：

<fragment xmlns:android="http://schemas.android.com/apk/res/android" 
      xmlns:map="http://schemas.android.com/apk/res-auto" 
      xmlns:tools="http://schemas.android.com/tools" 
      android:id="@+id/map" 
      android:name="com.google.android.gms.maps.SupportMapFragment" 
      android:layout_width="match_parent" 
      android:layout_height="match_parent" 
      tools:context="com.example.user.project.MapsActivity"/> 

我按照教程和文檔從OpenWeatherMap，谷歌地圖API和Android開發者提供的，但不明白爲什麼這不起作用。

我錯過了什麼？

Answer 1

您正在將級別8設置爲地圖的縮放級別，但您也將縮放級別限制在12和16之間，以使TileProvider可見。

刪除此：

if (!checkTileExists(x, y, zoom)) { 
    return null; 
} 

如果您不需要任何規模的限制，你還可以去除checkTileExists方法。