1. 关掉mysql服务，打开系统设置最后的mysql,然后将mysql先关掉
2. 生成一个文件命名mysql-init，文件中放入：一句话，这句话不同版本不一样，如下：（括号里面不包含）
alter user ‘root’@‘localhost’ identified by ‘新密码’；(MySQL 5.7.6 and later)
set password for ‘root’@‘localhost’=password(‘新密码’);(MySQL 5.7.5 and earlier)
3. cd /usr/local/mysql/bin/
sudo su
mysqld_safe —init-file=/home/me/mysql-init &
mysqld_safe —skip-grant-tables &
./mysql
flush privileges;
update mysql.user set authentication_string = password(‘你在文件中定义的新密码’)，password_expired = ’N’ where user = ‘root’ and host = ‘localhost’;
flush privileges;
quit;
./mysql -u root -p
输入你的新密码就好了
参考：B.5.3.2.2 Resetting the Root Password: Unix and Unix-Like Systems小节(http://dev.mysql.com/doc/refman/5.7/en/resetting-permissions.html)