獲取用戶登錄信息

在上一篇博客中，實現了登錄、登錄憑證模塊的開發，今天，通過昨天session中的登錄憑證，是的其他請求可以持有用戶信息。主要利用攔截器以及ThreadLocal。

重寫攔截器的三個方法preHandle、postHandle、afterCompletion。分別實現獲取用戶信息，並保存到ThreadLocal中、向ModelAndView 中傳入用戶信息、以及清空ThreadLocal中用戶的功能。通過HostHolder工具類封裝起ThreadLocal的相應操作。 

package com.nowcoder.community.controller.interceptor;

import com.nowcoder.community.entity.LoginTicket;
import com.nowcoder.community.entity.User;
import com.nowcoder.community.service.UserService;
import com.nowcoder.community.util.CookieUtil;
import com.nowcoder.community.util.HostHolder;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.util.Date;

@Component
public class LoginTicketInterceptor implements HandlerInterceptor {

    @Autowired
    private UserService userService;

    @Autowired
    private HostHolder hostHolder;

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        // 從cookie中獲取憑證
        String ticket = CookieUtil.getValue(request, "ticket");

        if (ticket != null) {
            // 查詢憑證
            LoginTicket loginTicket = userService.findLoginTicket(ticket);
            // 檢查憑證是否有效
            if (loginTicket != null && loginTicket.getStatus() == 0 && loginTicket.getExpired().after(new Date())) {
                // 根據憑證查詢用戶
                User user = userService.findUserById(loginTicket.getUserId());
                // 在本次請求中持有用戶
                hostHolder.setUser(user);
            }
        }

        return true;
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        User user = hostHolder.getUser();
        if (user != null && modelAndView != null) {
            modelAndView.addObject("loginUser", user);
        }
    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        hostHolder.clear();
    }
}

package com.nowcoder.community.util;

import com.nowcoder.community.entity.User;
import org.springframework.stereotype.Component;

/**
 * 持有用戶信息,用於代替session對象.
 */
@Component
public class HostHolder {

    private ThreadLocal<User> users = new ThreadLocal<>();

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

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

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

}

此外，寫了一個注解。通過攔截器對方法判斷是否有@LoginRequired注解，若有改注解則需要先登錄。

注解聲明很簡單，只需通過元注解標明注解作用的目標和注解的保留位置。

package com.nowcoder.community.annotation;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface LoginRequired {



}

再寫一個攔截器檢驗是否有@LoginRequired注解

package com.nowcoder.community.controller.interceptor;

import com.nowcoder.community.annotation.LoginRequired;
import com.nowcoder.community.util.HostHolder;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import org.springframework.web.method.HandlerMethod;
import org.springframework.web.servlet.HandlerInterceptor;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.lang.reflect.Method;

@Component
public class LoginRequiredInterceptor implements HandlerInterceptor {

    @Autowired
    private HostHolder hostHolder;

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        if (handler instanceof HandlerMethod) {
            HandlerMethod handlerMethod = (HandlerMethod) handler;
            Method method = handlerMethod.getMethod();
            LoginRequired loginRequired = method.getAnnotation(LoginRequired.class);
            if (loginRequired != null && hostHolder.getUser() == null) {
                response.sendRedirect(request.getContextPath() + "/login");
                return false;
            }
        }
        return true;
    }
}

攔截器配置類代碼如下

package com.nowcoder.community.config;

import com.nowcoder.community.controller.interceptor.AlphaInterceptor;
import com.nowcoder.community.controller.interceptor.LoginRequiredInterceptor;
import com.nowcoder.community.controller.interceptor.LoginTicketInterceptor;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

@Configuration
public class WebMvcConfig implements WebMvcConfigurer {

    @Autowired
    private LoginTicketInterceptor loginTicketInterceptor;

    @Autowired
    private LoginRequiredInterceptor loginRequiredInterceptor;

    @Override
    public void addInterceptors(InterceptorRegistry registry) {

        registry.addInterceptor(loginTicketInterceptor)
                .excludePathPatterns("/**/*.css", "/**/*.js", "/**/*.png", "/**/*.jpg", "/**/*.jpeg");

        registry.addInterceptor(loginRequiredInterceptor)
                .excludePathPatterns("/**/*.css", "/**/*.js", "/**/*.png", "/**/*.jpg", "/**/*.jpeg");
    }

}