添加全局常量类

+package com.sunyo.wlpt.message.bus.service.common;
+
+/**
+ * @author 子诚
+ * Description：常量公共类
+ * 时间：2020/7/17 9:49
+ */
+public class Constant {
+    public static final String EXIST_SERVERNAME = "MQ服务器名称已存在";
+}