diff --git a/src/main/java/club/joylink/xiannccda/ats/message/MessageData.java b/src/main/java/club/joylink/xiannccda/ats/message/MessageData.java
index e3880e7..32a45e0 100644
--- a/src/main/java/club/joylink/xiannccda/ats/message/MessageData.java
+++ b/src/main/java/club/joylink/xiannccda/ats/message/MessageData.java
@@ -49,7 +49,9 @@ public abstract class MessageData {
    *
    * @return
    */
-  public abstract int messageLength();
+  public int messageLength() {
+    return 8;
+  }
 
   public ByteBuf encode() {
     final int messageLength = this.messageLength();
@@ -67,6 +69,7 @@ public abstract class MessageData {
    *
    * @param buf
    */
-  protected abstract void encode2(ByteBuf buf);
+  protected void encode2(ByteBuf buf) {
+  }
 
 }