diff --git a/net/src/main/java/com/zfoo/net/handler/codec/json/JsonWebSocketCodecHandler.java b/net/src/main/java/com/zfoo/net/handler/codec/json/JsonWebSocketCodecHandler.java
index 98e2adbb..93a43869 100644
--- a/net/src/main/java/com/zfoo/net/handler/codec/json/JsonWebSocketCodecHandler.java
+++ b/net/src/main/java/com/zfoo/net/handler/codec/json/JsonWebSocketCodecHandler.java
@@ -44,7 +44,7 @@ public class JsonWebSocketCodecHandler extends MessageToMessageCodec<WebSocketFr
         var packetStr = jsonMap.get("packet");
         var attachmentStr = jsonMap.get("attachmentId");
         IAttachment attachment = null;
-        if (!StringUtils.isEmpty(attachmentStr)) {
+        if (StringUtils.isNotEmpty(attachmentStr)) {
             var attachmentId = Short.parseShort(attachmentStr);
             if (attachmentId >= 0) {
                 var attachmentClass = ProtocolManager.getProtocol(attachmentId).protocolConstructor().getDeclaringClass();