Merge branch '333-tile-server-caching' into 'master'

Resolve "Tile server: caching"

Closes #333

See merge request genesys-pgr/genesys-server!226

src/main/java/org/genesys2/server/api/v1/TileController.java

@@ -56,7 +56,20 @@ public class TileController {
 
         response.setContentType(MediaType.IMAGE_PNG_VALUE);
         response.setContentLength(image.length);
-        response.setHeader(HttpHeaders.CACHE_CONTROL, "max-age=3600, s-maxage=3600, public, no-transform");
+
+		// HTTP maxAge
+		int maxAge;
+		if (zoom < 4) {
+			maxAge = 60 * 60 * 24; // 24 hrs
+		} else if (zoom < 6) {
+			maxAge = 60 * 60 * 2; // 2 hrs
+		} else if (zoom < 8) {
+			maxAge = 60 * 60; // 1 hr
+		} else {
+			maxAge = 60 * 5; // 5 min
+		}
+		response.setHeader(HttpHeaders.CACHE_CONTROL, "max-age=" + maxAge + ", s-maxage=" + maxAge + ", public, no-transform");
 		response.getOutputStream().write(image, 0, image.length);
+		response.getOutputStream().flush();
     }
 }