mysql use utf8 encoding

1.add some parameters on my.conf
#vim /etc/mysql/my.cnf
add two lines on [mysqld] section
default-character-set=utf8
skip-character-set-client-handshake

2.on mysql 5.5 add these into my.conf

init_connect='SET collation_connection = utf8_unicode_ci'
init_connect='SET NAMES utf8'
character-set-server=utf8
collation-server=utf8_unicode_ci
skip-character-set-client-handshake