//1.构建securityManager工厂，加载资源文件中的shiro.ini
IniSecurityManagerFactory factory = new IniSecurityManagerFactory("classpath:shiro.ini");
//2.通过工厂创建securityManager
SecurityManager instance = factory.getInstance();
//3.将securityManager设置到运行环境中
SecurityUtils.setSecurityManager(instance);
//4.创建一个Subject实例
Subject subject = SecurityUtils.getSubject();
//5.创建token令牌
UsernamePasswordToken token = new UsernamePasswordToken("itlike", "1234");
//6.用户登陆
try{
    subject.login(token);
}catch (UnknownAccountException u){
    System.out.println("账号错误");
    u.printStackTrace();
}catch (IncorrectCredentialsException i){
    System.out.println("密码错误");
    i.printStackTrace();
}
System.out.println("是否认证："+subject.isAuthenticated());
//7.用户退出
subject.logout();
System.out.println("是否认证："+subject.isAuthenticated());

shiro.ini文件
[users]
itlike=1234
my=1234