文件不存在时，就不显示图标

src/main/java/com/archser/aserver/controller/SettingController.java

@@ -122,7 +122,14 @@ public class SettingController extends Controller {
   public void logoUrl() {
     String filePath =
         PathKit.getRootClassPath()+ File.separator + "logo.png";
+    /**chenyong 20201218 文件不存在时，就不显示图标**/
+    File file=new File(filePath);
+    if(file.exists()) {
       this.renderJson(Ret.ok("logoUrl", ImageToBase64(filePath)));
+    }else {
+      this.renderJson(Ret.fail("logoUrl", ImageToBase64("")));
+    }
+    
   }
 
   private static String ImageToBase64(String imgPath) {