修复导出没有传链接字符串的问题

AppStart/Helper/ExportService.cs

@@ -112,11 +112,18 @@ namespace MySystem
             string ConnectStr = "";
             if(content.Contains("\"ConnectStr\""))
             {
-                ConnectStr = GetConnectStr(jsonObj["ConnectStr"].ToString());
+                if(!string.IsNullOrEmpty(jsonObj["ConnectStr"].ToString()))
+                {
+                    ConnectStr = GetConnectStr(jsonObj["ConnectStr"].ToString());
+                }
+                else
+                {
+                    ConnectStr = MysqlConn.readconnstr;
+                }
             }
             else
             {
-                ConnectStr = MysqlConn.connstr;
+                ConnectStr = MysqlConn.readconnstr;
             }
             bool SubSqlFlag = content.Contains("\"SubSqlString\"");