import com.google.maps.android.projection.SphericalMercatorProjection; //导入依赖的package包/类
@Override
public Set<? extends Cluster<T>> getClusters(double zoom) {
    long numCells = (long) Math.ceil(256 * Math.pow(2, zoom) / GRID_SIZE);
    SphericalMercatorProjection proj = new SphericalMercatorProjection(numCells);

    HashSet<Cluster<T>> clusters = new HashSet<Cluster<T>>();
    LongSparseArray<StaticCluster<T>> sparseArray = new LongSparseArray<StaticCluster<T>>();

    synchronized (mItems) {
        for (T item : mItems) {
            Point p = proj.toPoint(item.getPosition());

            long coord = getCoord(numCells, p.x, p.y);

            StaticCluster<T> cluster = sparseArray.get(coord);
            if (cluster == null) {
                cluster = new StaticCluster<T>(proj.toLatLng(new Point(Math.floor(p.x) + .5, Math.floor(p.y) + .5)));
                sparseArray.put(coord, cluster);
                clusters.add(cluster);
            }
            cluster.add(item);
        }
    }

    return clusters;
}
 

import com.google.maps.android.projection.SphericalMercatorProjection; //导入依赖的package包/类
public void setMapZoom(float zoom) {
    this.mMapZoom = zoom;
    this.mSphericalMercatorProjection = new SphericalMercatorProjection(256 * Math.pow(2, Math.min(zoom, mZoom)));
}