update

src/main/java/com/lovenav/utils/UrlCheckUtil.java

@@ -124,6 +124,6 @@ public class UrlCheckUtil {
             }
         }
         double averageResponseTime = (double) totalResponseTime / (1 * numRequests);
-        return JSON.toJSONString(averageResponseTime + " ms");
+        return averageResponseTime + " ms";
     }
 }