如何利用LRUCache製作安卓端谷歌地圖的三級快取
阿新 • • 發佈：2018-12-12
第一個檔案，繼承ArcGIS的TileServerLayer
/**
*
* @author wjf
* @date 2018/09/30
*/
public class GoogleMapLayer extends TiledServiceLayer {
private static final int MAXLRU_SIZE=1024*1024*8*1;//假設為1M；
private final int MIN_LEVEL = 0;//設定縮放的最小級別
private final int MAX_LEVEL = 19;//設定縮放的最大級別,這裡最大層級19，可以自定義（需要在下方的 MAP_SCALE 和 RESOLUTIONS 中設定相對應的資料）
private int GoogleMapLayerType;
private MapCacheHelper cacheHelper;
private double[] MAP_SCALE = new double[]{591657527.591555,
295828763.79577702, 147914381.89788899, 73957190.948944002,
36978595.474472001, 18489297.737236001, 9244648.8686180003,
4622324.4343090001, 2311162.217155, 1155581.108577, 577790.554289,
288895.277144, 144447.638572, 72223.819286, 36111.909643,
18055.954822, 9027.9774109999998, 4513.9887049999998, 2256.994353,
1128.4971760000001};
private double[] RESOLUTIONS = new double[]{156543.03392800014,
78271.516963999937, 39135.758482000092, 19567.879240999919,
9783.9396204999593, 4891.9698102499797, 2445.9849051249898,
1222.9924525624949, 611.49622628138, 305.748113140558,
152.874056570411, 76.4370282850732, 38.2185141425366,
19.1092570712683, 9.55462853563415, 4.7773142679493699,
2.3886571339746849, 1.1943285668550503, 0.59716428355981721,
0.29858214164761665};
private Point ORIGIN_PNT = new Point(-20037508.342787, 20037508.342787);
private int DPI = 96;
private int TILEWIDTH = 256;
private int TILEHEIGHT = 256;
public GoogleMapLayer(int layerType) {
super(true);
this.GoogleMapLayerType = layerType;
this.init();
}
private void init() {
try {
getServiceExecutor().submit(() -> GoogleMapLayer.this.initLayer());
// 這裡是設定快取到本地的路徑 可以自定義
String imgPtPath = AppConsts.CACHE_DIR + "/t" + GoogleMapLayerType + "/";
cacheHelper=new MapCacheHelper(GoogleMapLayerType,MAXLRU_SIZE,imgPtPath);
} catch (RejectedExecutionException rejectedexecutionexception) {
Log.e("Google Map Layer", "initialization of the layer failed.", rejectedexecutionexception);
}
}
@Override
protected byte[] getTile(int level, int col, int row) throws Exception {
byte[] res;
if (level > MAX_LEVEL || level < MIN_LEVEL) {
return new byte[0];
}
String s = "Galileo".substring(0, ((3 * col + row) % 8));
String url = getMapUrl(level,col,row,s);
//開始獲取三級快取1、記憶體
if((res=cacheHelper.getMapCache(url))!=null){
return res;
}else if((res=cacheHelper.getLocalMapCache(level,col,row))!=null){
cacheHelper.setMapCache(url,res);
return res;
}else{
if (isNetworkAvailable(MyApp.getContext())) {
Map<String, String> map = null;
res= com.esri.core.internal.io.handler.a.a(url, map);
cacheHelper.setLocalMapCache(level,col,row,res);
cacheHelper.setMapCache(url,res);
return res;
}else{
}
}
return new byte[0];
}
protected SpatialReference getSptialReference() {
return this.getDefaultSpatialReference();
}
@Override
protected void initLayer() {
if (getID() == 0L) {
nativeHandle = create();
changeStatus(com.esri.android.map.event.OnStatusChangedListener.STATUS.fromInt(-1000));
} else {
this.setDefaultSpatialReference(SpatialReference.create(102113));
this.setFullExtent(new Envelope(-20037508.34, -20037508.34, 20037508.34, 20037508.34));
this.setTileInfo(new TileInfo(ORIGIN_PNT, MAP_SCALE, RESOLUTIONS, MAP_SCALE.length, DPI, TILEWIDTH, TILEHEIGHT));
super.initLayer();
}
}
private boolean isNetworkAvailable(Context context) {
ConnectivityManager manager = (ConnectivityManager) context.getApplicationContext().getSystemService(Context.CONNECTIVITY_SERVICE);
if (manager == null) {
return false;
}
NetworkInfo networkinfo = manager.getActiveNetworkInfo();
if (networkinfo == null || !networkinfo.isAvailable()) {
return false;
}
return true;
}
public String getMapUrl(int level, int col, int row,String s){
String url="";
switch (GoogleMapLayerType) {
case GoogleMapLayerTypes.IMAGE_GOOGLE_MAP:
url = "http://mt" + (col % 4) + ".google.cn/vt/lyrs=s&hl=zh-CN&gl=cn&" +
"x=" + col + "&" +
"y=" + row + "&" +
"z=" + level + "&" +
"s=" + s;
break;
case GoogleMapLayerTypes.VECTOR_GOOGLE_MAP:
url = "http://mt2.google.cn/vt/
第二個檔案：
public interface GoogleMapLayerTypes {
/**
* 谷歌向量地圖服務
*/
int VECTOR_GOOGLE_MAP = 1;
/**
* 谷歌影像地圖服務
*/
int IMAGE_GOOGLE_MAP = 2;
/**
* 谷歌地形地圖服務
*/
int TERRAIN_GOOGLE_MAP = 3;
/**
* 谷歌道路等POI地圖服務
*/
int ANNOTATION_GOOGLE_MAP = 4;
}
第三個檔案 實現快取
**
* @author:wjf
* @date:20180930
* 為谷歌地圖配置相對應的
*/
public class MapCacheHelper {
private int GoogleMapLayerType;
LruCache<String,byte[]> myLruCache;
String filePath;
/**
*
* @param googleMapLayerType 地圖型別
* @param mapLRUCapacity LRUCache的大小
* @param filePath 存放本地快取的路徑
*/
public MapCacheHelper(int googleMapLayerType, int mapLRUCapacity, String filePath){
this.GoogleMapLayerType=googleMapLayerType;
this.filePath=filePath;
FileUtils.createDirs(filePath);
myLruCache=new LruCache<String,byte[]>(mapLRUCapacity){
@Override
protected int sizeOf(String key, byte[] value) {
return value.length;
}
};
}
public byte[] getMapCache(String url){
return myLruCache.get(url);
}
public void setMapCache(String url,byte[] data){
myLruCache.put(url,data);
}
private byte[] getLocalMapCache(String imgPath,String imgName){
Bitmap bitmap = BitmapFactory.decodeFile(imgPath + imgName);
if(bitmap==null) return null;
ByteArrayOutputStream baos = new ByteArrayOutputStream();
bitmap.compress(Bitmap.CompressFormat.PNG, 100, baos);
return baos.toByteArray();
}
public byte[] getLocalMapCache(int level, int col, int row){
String imgPath = filePath+ "l" + level + "/";
String imgName = "c" + col + "r" + row + ".png";
return getLocalMapCache(imgPath,imgName);
}
private void saveFile(String filePath, byte[] data, String fileName) throws IOException {
Bitmap mBitmap = BitmapFactory.decodeByteArray(data, 0, data.length);// bitmap
File dirFile = new File(filePath);
if (!dirFile.exists()) {
dirFile.mkdir();
}
// 檢測是否有 .nomedia 檔案，該檔案防止相簿等媒體軟體掃描離線地圖圖片，以免造成不必要的麻煩
File nomediaFile = new File(filePath + ".nomedia");
if (!nomediaFile.exists()) {
nomediaFile.createNewFile();
}
File myCaptureFile = new File(filePath + fileName);
// 判斷離線的圖片是否已經存在，已經存在的地圖不用再次下載（節省流量）
if (myCaptureFile.exists()) {
return;
}
BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(myCaptureFile));
mBitmap.compress(Bitmap.CompressFormat.PNG, 80, bos);
bos.flush();
bos.close();
}
public void setLocalMapCache(int level, int col, int row, byte[] data){
try {
String imgPath = filePath+ "l" + level + "/";
String imgName = "c" + col + "r" + row + ".png";
saveFile(imgPath,data, imgName);
} catch (IOException e) {
e.printStackTrace();
}
}
}