Android map顯示藍屏而不是map

Question

我有用於在 map 上顯示兩個位置的代碼，但它只顯示標記，而不是 map，它只顯示藍屏。 我在移動設備上運行，而不是模擬器。

我的代碼：

public class HelloGoogleMaps3 extends MapActivity {
    private MapView map=null;
    private MyLocationOverlay me=null;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        map=(MapView)findViewById(R.id.map);

        map.getController().setCenter(getPoint
                (40.76793169992044,-173.98180484771729));
        map.getController().setZoom(17);
        map.setBuiltInZoomControls(true);

        Drawable marker=getResources().getDrawable(R.drawable.marker);

        marker.setBounds(0, 0, marker.getIntrinsicWidth(),
                        marker.getIntrinsicHeight());

        map.getOverlays().add(new SitesOverlay(marker));

        me=new MyLocationOverlay(this, map);
        map.getOverlays().add(me);
    }

    @Override
    public void onResume() {
        super.onResume();

        me.enableCompass();
    }       

    @Override
    public void onPause() {
        super.onPause();

        me.disableCompass();
    }       

    @Override
    protected boolean isRouteDisplayed() {
        return(false);
    }

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if (keyCode == KeyEvent.KEYCODE_S) {
            map.setSatellite(!map.isSatellite());
            return(true);
        }
        else if (keyCode == KeyEvent.KEYCODE_Z) {
            map.displayZoomControls(true);
            return(true);
        }

        return(super.onKeyDown(keyCode, event));
    }

    private GeoPoint getPoint(double lat, double lon) {
        return(new GeoPoint((int)(lat*1000000.0),
                            (int)(lon*1000000.0)));
    }

    private class SitesOverlay extends ItemizedOverlay<OverlayItem> {
        private List<OverlayItem> items=new ArrayList<OverlayItem>();
        private Drawable marker=null;

        public SitesOverlay(Drawable marker) {
            super(marker);
            this.marker=marker;

            items.add(new OverlayItem(getPoint
                    (40.748963847316034,-173.96807193756104),
                                "UN", "United Nations"));
            items.add(new OverlayItem(getPoint
                    (40.76866299974387,-173.98268461227417),
                                "Lincoln Center",
                                "Home of Jazz at Lincoln Center"));
            items.add(new OverlayItem(getPoint
                    (40.765136435316755,-173.97989511489868),
                                "Carnegie Hall",
                        "Where you go with practice, practice, practice"));
            items.add(new OverlayItem(getPoint
                    (40.70686417491799,-174.01572942733765),
                                "The Downtown Club",
                        "Original home of the Heisman Trophy"));

            populate();
        }

        @Override
        protected OverlayItem createItem(int i) {
            return(items.get(i));
        }

        @Override
        public void draw(Canvas canvas, MapView mapView,
                                        boolean shadow) {
            super.draw(canvas, mapView, shadow);

            boundCenterBottom(marker);
        }

        @Override
        protected boolean onTap(int i) {
            Toast.makeText(HelloGoogleMaps3.this,
                                items.get(i).getSnippet(),
                                Toast.LENGTH_SHORT).show();

            return(true);
        }

        @Override
        public int size() {
            return(items.size());
        }
    }
}

我做錯了什么？

Answer 1

這可能意味着以下兩件事之一：

一個。 您的 API 密鑰不正確

灣。 您的坐標設置為 (0, 0)，並且 map 標記指向海洋。 嘗試將 map 放大。您可能會看到土地。 :)

Answer 2

如果您從位置管理器獲取位置並嘗試使用坐標而不首先轉換它們，則可能會發生這種情況：

Location location = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
// location.getLatitude() is, say, 56.8751841974
// location.getLongitude() is, say, -3.9548756201
GeoPoint mapPoint = new GeoPoint((int)(location.getLatitude() * 1E6), (int)(location.getLongitude() * 1E6));

基本上，您需要將值乘以 100 萬到 map 到正確的坐標。

Answer 3

您可以使用不同的坐標集自定義 MapView 顏色，例如：

• 40.76793169992044,-173.98180484771729 是藍色的，正如您所經歷的
• -77.199943,11.913063為淺灰色
• 75.913515,-30.443115 為綠色
• 43.318418,11.331644 是錫耶納