从网上找到如下资料：
$sudo gedit /etc/mysql/my.cnf
[client]下添加：
default-character-set=utf8
[mysqld]下添加：
default-character-set=utf8
然后保存退出
$ /etc/init.d/mysql restart
结果出现了:
Since the script you are attempting to invoke has been converted to an
Upstart job, you may also use the stop(8) and then start(8) utilities,
e.g. stop mysql ; start mysql. The restart(8) utility is also available.
start: Job failed to start
----------------------------------------------------------------------------------------------------------------------------
可能是版本的问题，查5.5以后的版本对字符编码方式修改的办法，发现[mysqld]修改方法变了：
[mysqld]下添加的应该为：
character-set-server=utf8
collation-server=utf8_general_ci
记住文档中已经存在的设置要注释掉
保存退出
$ /etc/init.d/mysql restart
成功
进入MySQL控制台：
show variables like 'character%';
+-----------------------------------+-----------------------------------+
| Variable_name | Value |
+-----------------------------------+-----------------------------------+
| character_set_client | utf8 |
| character_set_connection | utf8 |
| character_set_database | utf8 |
| character_set_filesystem | binary |
| character_set_results | utf8 |
| character_set_server | utf8 |
| character_set_system | utf8 |
| character_sets_dir | /usr/share/mysql/charsets/ |
+------------------------------------+-----------------------------------+
8 rows in set (0.00 sec)