java - Android Google Maps V2 - SD 卡作为 Tile Provider

Question

我正在使用 Google Maps API V2 开发一个 Android 应用程序，我必须使用离线图 block ，我的 SD 卡中有我整个城市的所有图 block (来自 png 格式的开放街道 map )。我已经尝试使用 TileProvider Interface 但没有用。我怎样才能做到这一点 ？提前致谢。

Answer 1

我修改了一些东西并且它起作用了。这是代码:

CustomMapTileProvider.java

public class CustomMapTileProvider implements TileProvider {
    private static final int TILE_WIDTH = 256;
    private static final int TILE_HEIGHT = 256;
    private static final int BUFFER_SIZE = 16 * 1024;

    Override
    public Tile getTile(int x, int y, int zoom) {
        byte[] image = readTileImage(x, y, zoom);
        return image == null ? null : new Tile(TILE_WIDTH, TILE_HEIGHT, image);
    }

    private byte[] readTileImage(int x, int y, int zoom) {
        FileInputStream in = null;
        ByteArrayOutputStream buffer = null;

        try { in = new FileInputStream(getTileFile(x, y, zoom));
            buffer = new ByteArrayOutputStream();
            int nRead;
            byte[] data = new byte[BUFFER_SIZE];

            while ((nRead = in .read(data, 0, BUFFER_SIZE)) != -1) {
                buffer.write(data, 0, nRead);
            }
            buffer.flush();
            return buffer.toByteArray();
        } catch (IOException e) {
            e.printStackTrace();
            return null;
        } catch (OutOfMemoryError e) {
            e.printStackTrace();
            return null;
        } finally {
            if ( in != null)
                try { in .close();
                } catch (Exception ignored) {}
            if (buffer != null)
                try {
                    buffer.close();
                } catch (Exception ignored) {}
        }
    }

    private File getTileFile(int x, int y, int zoom) {
        File sdcard = Environment.getExternalStorageDirectory();
        String tileFile = "/TILES_FOLDER/" + zoom + '/' + x + '/' + y + ".png";
        File file = new File(sdcard, tileFile);
        return file;
    }
}

将 TileOverlay 添加到您的 GoogleMap 实例

...

map.setMapType(GoogleMap.MAP_TYPE_NONE);
TileOverlayOptions tileOverlay = new TileOverlayOptions();
tileOverlay.tileProvider(new CustomMapTileProvider());
map.addTileOverlay(tileOverlay).setZIndex(0);

...