shiro认证过程

Subject currentUser = SecurityUtils.getSubject();
UsernamePasswordToken token = new UsernamePasswordToken(username, password);
token.setRememberMe(true);
try {
　　currentUser.login(token);
} catch (UnknownAccountException e) {
　　logger.error(String.format("user not found: %s", username), e); // 用户不存在
} catch (IncorrectCredentialsException e) {
　　logger.error(String.format("incorrent credentials: %s", username), e); // 密码不正确
} catch (ConcurrentAccessException e) {
　　logger.error(String.format("user has been authenticated: %s", username), e); // 用户重复登录
} catch (AccountException e) {
　　logger.error(String.format("account except: %s", username), e); // 其他账户异常
}