Change image response to 204 and always save an empty players.json

BlueMapCommon/src/main/java/de/bluecolored/bluemap/common/web/MapStorageRequestHandler.java

@@ -131,9 +131,18 @@ public class MapStorageRequestHandler implements HttpRequestHandler {
             return new HttpResponse(HttpStatusCode.INTERNAL_SERVER_ERROR);
         }
 
-        HttpResponse response = new HttpResponse(HttpStatusCode.OK);
-        response.setData("{}");
-        return response;
+        if (path.endsWith(".png")) {
+            return new HttpResponse(HttpStatusCode.NO_CONTENT);
+        }
+
+        if (path.endsWith(".json")) {
+            HttpResponse response = new HttpResponse(HttpStatusCode.OK);
+            response.addHeader("Content-Type", "application/json");
+            response.setData("{}");
+            return response;
+        }
+
+        return new HttpResponse(HttpStatusCode.NOT_FOUND);
     }
 
     private String calculateETag(String path, TileInfo tileInfo) {

BlueMapCommon/src/main/java/de/bluecolored/bluemap/common/web/http/HttpStatusCode.java

@@ -30,6 +30,7 @@ public enum HttpStatusCode {
     PROCESSING (102, "Processing"),
 
     OK (200, "OK"),
+    NO_CONTENT (204, "No Content"),
 
     MOVED_PERMANENTLY (301, "Moved Permanently"),
     FOUND (302, "Found"),

BlueMapCore/src/main/java/de/bluecolored/bluemap/core/map/BmMap.java

@@ -39,6 +39,7 @@ import de.bluecolored.bluemap.core.world.Grid;
 import de.bluecolored.bluemap.core.world.World;
 
 import java.io.*;
+import java.nio.charset.StandardCharsets;
 import java.util.Map;
 import java.util.Objects;
 import java.util.Optional;
@@ -134,6 +135,7 @@ public class BmMap {
         lowresTileManager.save();
         saveRenderState();
         saveMarkerState();
+        savePlayerState();
         saveMapSettings();
 
         // only save texture gallery if not present in storage
@@ -215,6 +217,16 @@ public class BmMap {
         }
     }
 
+    public synchronized void savePlayerState() {
+        try (
+                OutputStream out = storage.writeMeta(id, META_FILE_PLAYERS);
+        ) {
+            out.write("{}".getBytes(StandardCharsets.UTF_8));
+        } catch (Exception ex) {
+            Logger.global.logError("Failed to save markers for map '" + getId() + "'!", ex);
+        }
+    }
+
     public String getId() {
         return id;
     }