Mysql Java connector detect wrong timezone from server

Question

I got a very strange problem.

My local timezone is UTC+8. I think server's timezone is also UTC+8 according to the following command:

mysql> SELECT TIMEDIFF(NOW(), UTC_TIMESTAMP);
+--------------------------------+
| TIMEDIFF(NOW(), UTC_TIMESTAMP) |
+--------------------------------+
| 08:00:00                       |
+--------------------------------+
1 row in set (0.01 sec)

But Java's driver detect the server's timezone is UTC-5. More specifically, assuming that my local time is 13:00, if I insert a new Date() into the database, then the actual time I inserted is 00:00.

However, if I append serverTimezone=Asia/Shanghai(which is UTF+8) to mysql's url, everything goes well.

Detail server's informations list below:

• Ubuntu 14.04.5 LTS

• Contents in /etc/timezone is Asia/Shanghai

• Mysql Server version: 5.6.31-0ubuntu0.14.04.2-log (Ubuntu)

• spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

• Driver version: mysql:mysql-connector-java:6.0.5

I've confused with this problem for long time, could anyone give me an answer?