主要目的是：

確定是使用者是否登陸，通過每次請求檢測ticket時候存在來實現。

基本原理：註冊攔截器+實現攔截器+設定執行緒副本變數

一、註冊攔截器：extends WebMvcConfigurerAdapter

@Component
public class WendaWebConfiguration extends WebMvcConfigurerAdapter {
@Autowired
PassportInterceptor passportInterceptor;

@Override
public void addInterceptors(InterceptorRegistry registry) {
    registry.addInterceptor(passportInterceptor);    
    super.addInterceptors(registry);
    }
}
 

二、實現攔截器：implements HandlerInterceptor

1、配置自己的Interceptor並實現HandlerInterceptor中三個方法。preHandler：指的是請求之前，主要是可以做獲取請求引數如cookie，並由此獲取cookie中的內容ticket，–》得到loginticket –》得到userId–》得到user的引數。

並把該讀取的物件設定到ThreadLocal中，實現併發訪問。hostholder.set();

2、postHandler：指的是請求之後返回了modelAndView即將用此modelAndView渲染之前，這時候可以在model中加入自己引數 model.addObject(“user”,hostHolder.get(user));

3、afterCompletion:請求完成之後清楚ThreadLocal中的執行緒區域性變數：hostHolder.clean()

@Component
public class PassportInterceptor implements HandlerInterceptor {

@Autowired
private LoginTicketDao loginTicketDAO;

@Autowired
private UserDao userDAO;

@Autowired
private HostHolder hostHolder;


@Override
public boolean preHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o) throws Exception {
    String ticket = null;
    if (httpServletRequest.getCookies() != null) {
        for (Cookie cookie : httpServletRequest.getCookies()) {
            if (cookie.getName().equals("ticket")) {
                ticket = cookie.getValue();
                break;
            }
        }
    }

    if (ticket != null) {
        LoginTicket loginTicket = loginTicketDAO.selectByTicket(ticket);
        if (loginTicket == null || loginTicket.getExpired().before(new Date()) || loginTicket.getStatus() != 0) {
            return true;
        }

        User user = userDAO.selectById(loginTicket.getUserId());
        hostHolder.setUser(user);
    }
    return true;
}

@Override
public void postHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, ModelAndView modelAndView) throws Exception {
    if (modelAndView != null && hostHolder.getUser() != null) {
        modelAndView.addObject("user", hostHolder.getUser());
        System.out.println("passposrt setting user"+hostHolder.getUser());
    }
}

@Override
public void afterCompletion(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, Exception e) throws Exception {
        hostHolder.clear();
    }
}
 

三、設定執行緒副本變數：implements HandlerInterceptor

@Component
public class HostHolder {
private static ThreadLocal<User> users = new ThreadLocal<User>();

public User getUser() {
    return users.get();
}

public void setUser(User user) {
    users.set(user);
}

public void clear() {
    users.remove();
}
}