获取用户登录信息

在上一篇博客中，实现了登录、登录凭证模块的开发，今天，通过昨天session中的登录凭证，是的其他请求可以持有用户信息。主要利用拦截器以及ThreadLocal。

重写拦截器的三个方法preHandle、postHandle、afterCompletion。分别实现获取用户信息，并保存到ThreadLocal中、向ModelAndView 中传入用户信息、以及清空ThreadLocal中用户的功能。通过HostHolder工具类封装起ThreadLocal的相应操作。 

 1 package com.nowcoder.community.controller.interceptor;
 2 
 3 import com.nowcoder.community.entity.LoginTicket;
 4 import com.nowcoder.community.entity.User;
 5 import com.nowcoder.community.service.UserService;
 6 import com.nowcoder.community.util.CookieUtil;
 7 import com.nowcoder.community.util.HostHolder;
 8 import org.springframework.beans.factory.annotation.Autowired;
 9 import org.springframework.stereotype.Component;
10 import org.springframework.web.servlet.HandlerInterceptor;
11 import org.springframework.web.servlet.ModelAndView;
12 
13 import javax.servlet.http.HttpServletRequest;
14 import javax.servlet.http.HttpServletResponse;
15 import java.util.Date;
16 
17 @Component
18 public class LoginTicketInterceptor implements HandlerInterceptor {
19 
20     @Autowired
21     private UserService userService;
22 
23     @Autowired
24     private HostHolder hostHolder;
25 
26     @Override
27     public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
28         // 从cookie中获取凭证
29         String ticket = CookieUtil.getValue(request, "ticket");
30 
31         if (ticket != null) {
32             // 查询凭证
33             LoginTicket loginTicket = userService.findLoginTicket(ticket);
34             // 检查凭证是否有效
35             if (loginTicket != null && loginTicket.getStatus() == 0 && loginTicket.getExpired().after(new Date())) {
36                 // 根据凭证查询用户
37                 User user = userService.findUserById(loginTicket.getUserId());
38                 // 在本次请求中持有用户
39                 hostHolder.setUser(user);
40             }
41         }
42 
43         return true;
44     }
45 
46     @Override
47     public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
48         User user = hostHolder.getUser();
49         if (user != null && modelAndView != null) {
50             modelAndView.addObject("loginUser", user);
51         }
52     }
53 
54     @Override
55     public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
56         hostHolder.clear();
57     }
58 }

package com.nowcoder.community.util;

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

/**
 * 持有用户信息,用于代替session对象.
 */
@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，写了一个注解。通过拦截器对方法判断是否有@LoginRequired注解，若有改注解则需要先登录。

注解声明很简单，只需通过元注解标明注解作用的目标和注解的保留位置。

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 {



}

再写一个拦截器检验是否有@LoginRequired注解

 1 package com.nowcoder.community.controller.interceptor;
 2 
 3 import com.nowcoder.community.annotation.LoginRequired;
 4 import com.nowcoder.community.util.HostHolder;
 5 import org.springframework.beans.factory.annotation.Autowired;
 6 import org.springframework.stereotype.Component;
 7 import org.springframework.web.method.HandlerMethod;
 8 import org.springframework.web.servlet.HandlerInterceptor;
 9 
10 import javax.servlet.http.HttpServletRequest;
11 import javax.servlet.http.HttpServletResponse;
12 import java.lang.reflect.Method;
13 
14 @Component
15 public class LoginRequiredInterceptor implements HandlerInterceptor {
16 
17     @Autowired
18     private HostHolder hostHolder;
19 
20     @Override
21     public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
22         if (handler instanceof HandlerMethod) {
23             HandlerMethod handlerMethod = (HandlerMethod) handler;
24             Method method = handlerMethod.getMethod();
25             LoginRequired loginRequired = method.getAnnotation(LoginRequired.class);
26             if (loginRequired != null && hostHolder.getUser() == null) {
27                 response.sendRedirect(request.getContextPath() + "/login");
28                 return false;
29             }
30         }
31         return true;
32     }
33 }

拦截器配置类代码如下

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");
    }

}