【项目】仿牛客网社区开发第2章 Spring Boot 实践开发社区登录模块 6 显示登录信息

小咪咪 2024-03-22 10:57 11阅读 0赞

### 【项目】仿牛客网社区开发 ###

#### 文章目录 ####

*   *  【项目】仿牛客网社区开发
     *   *  第2章 Spring Boot 实践 开发社区登录模块
         *   *  6 显示登录信息

![在这里插入图片描述][d0bc69daec4c4786862d9178bf3edc56.png_pic_center]

#### 第2章 Spring Boot 实践 开发社区登录模块 ####

##### 6 显示登录信息 #####

*  拦截器示例
    
     *  定义拦截器，实现HandlerInterceptor
     *  配置拦截器，为它指定拦截、排除的路径
 *  拦截器应用
    
     *  在请求开始时查询登录用户
     *  在本次请求中持有用户数据
     *  在模板视图上显示用户数据
     *  在请求结束时清理用户数据

![在这里插入图片描述][a8f5cddbf1974caea10ec9a21935c0ab.png_pic_center]

即根据登录与否，调整我们的页面头部显示的东西，现在我们的效果是，嗯，登没登陆都一样

【先来看看拦截器的示例，了解一下先】

package com.nowcoder.community.controller.interceptor;
    
    import org.slf4j.Logger;
    import org.slf4j.LoggerFactory;
    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;
    
    /**
     * @Projectname: community
     * @Classname: AlphaInterceptor
     * @Author: Ding Jiaxiong
     * @Date:2023/4/18 14:07
     */
    
    @Component
    public class AlphaInterceptor implements HandlerInterceptor {
        
    
        private static final Logger logger = LoggerFactory.getLogger(AlphaInterceptor.class);
    
        // 在Controller 之前执行
        @Override
        public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        
            logger.debug("preHandle: " + handler.toString());
            return true;
        }
    
        // 在controller 之后执行
        @Override
        public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        
            logger.debug("postHandle: " + handler.toString());
        }
    
        // 在模板引擎之后, 最后执行
        @Override
        public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        
            logger.debug("afterCompletion: " + handler.toString());
        }
    }

![在这里插入图片描述][034a41d3f26d4949afa7b4fa6e3b74f3.png_pic_center]

再来一个配置类

package com.nowcoder.community.config;
    
    import com.nowcoder.community.controller.interceptor.AlphaInterceptor;
    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;
    
    /**
     * @Projectname: community
     * @Classname: WebMvcConfig
     * @Author: Ding Jiaxiong
     * @Date:2023/4/18 14:12
     */
    
    @Configuration
    public class WebMvcConfig implements WebMvcConfigurer {
        
    
        @Autowired
        private AlphaInterceptor alphaInterceptor;
    
        @Override
        public void addInterceptors(InterceptorRegistry registry) {
        
            registry.addInterceptor(alphaInterceptor)
                    .excludePathPatterns("/**/*.css", "/**/*.js", "/**/*.png", "/**/*.jpg", "/**/*.jpeg")
                    .addPathPatterns("/register", "/login");
        }
    }

OK， 现在的意思就是放开静态资源，拦截`/register` 以及 `/login`

启动服务器，访问首页

![在这里插入图片描述][24176fafb732431a8451084764d8120f.png_pic_center]

没有打印我们设置那些日志，访问登录

![在这里插入图片描述][227a5836e04b4f9d83553e35a9e8d751.png_pic_center]

日志出来了

同理，试试注册

![在这里插入图片描述][a53b53fd169947d29056dcc1c0af7f7c.png_pic_center]

这就是被拦截到了。

OK，现在我们就要用这个东西来解决我们的实际问题了

拦截器应用

*  在请求开始时查询登录用户
 *  在本次请求中持有用户数据
 *  在模板视图上显示用户数据
 *  在请求结束时清理用户数据

先理清一下思路：

![在这里插入图片描述][735bd0c93b424f649e1b562cecc78b7b.png_pic_center]

编写代码：【注意这一系列操作我们别通过发送多次请求来解决，而是通过拦截器一次性实现】

先来一个Cookie 工具类：

package com.nowcoder.community.util;
    
    import javax.servlet.http.Cookie;
    import javax.servlet.http.HttpServletRequest;
    
    /**
     * @Projectname: community
     * @Classname: CookieUtil
     * @Author: Ding Jiaxiong
     * @Date:2023/4/18 15:16
     */
    
    public class CookieUtil {
        
    
        public static String getValue(HttpServletRequest request, String name) {
        
            if (request == null || name == null) {
        
                throw new IllegalArgumentException("参数为空!");
            }
    
            Cookie[] cookies = request.getCookies();
            if (cookies != null) {
        
                for (Cookie cookie : cookies) {
        
                    if (cookie.getName().equals(name)) {
        
                        return cookie.getValue();
                    }
                }
            }
    
            return null;
        }
    
    }

![在这里插入图片描述][96cfda488e2541d2874d3cf42e098498.png_pic_center]

和一个持有用户信息的类，用于代替session 对象

package com.nowcoder.community.util;
    
    import com.nowcoder.community.entity.User;
    import org.springframework.stereotype.Component;
    
    /**
     * @Projectname: community
     * @Classname: HostHolder
     * @Author: Ding Jiaxiong
     * @Date:2023/4/18 15:32
     */
    
    @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();
        }
    
    }

来一个正经的拦截器类：

package com.nowcoder.community.controller.interceptor;
    
    /**
     * @Projectname: community
     * @Classname: LoginTicketInterceptor
     * @Author: Ding Jiaxiong
     * @Date:2023/4/18 15:13
     */
    
    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 {
        
            // 从cookie中获取凭证
            String ticket = CookieUtil.getValue(request, "ticket");
    
            if (ticket != null) {
        
                // 查询凭证
                LoginTicket loginTicket = userService.findLoginTicket(ticket);
                // 检查凭证是否有效
                if (loginTicket != null && loginTicket.getStatus() == 0 && loginTicket.getExpired().after(new Date())) {
        
                    // 根据凭证查询用户
                    User user = userService.findUserById(loginTicket.getUserId());
                    // 在本次请求中持有用户
                    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();
        }
    }

在配置类中进行配置

![在这里插入图片描述][4904cd3681d84c1fb66bd1dc4764181a.png_pic_center]

接着修改显示首页的模板

![在这里插入图片描述][d133e8ad309e4d8dbdb9e5820d222113.png_pic_center]

OK， 启动服务器试试

![在这里插入图片描述][86103b1867fb4a04ac2f934dc9e62dc6.png_pic_center]

访问首页

![在这里插入图片描述][53c8bb446d7d422f8411584476796042.png_pic_center]

进行登录操作

![在这里插入图片描述][e1a5e9bcc7bd4f1da58f742e23dfdc4f.png_pic_center]

![在这里插入图片描述][504b1f9d7d9e47bfae269328d233715f.png_pic_center]

没问题，登出

![在这里插入图片描述][81f12c05ab8345d3a4dbc96f344a9ac2.png_pic_center]

没问题，因为凭证失效了，所以显示回去

![在这里插入图片描述][1492fa6ae2ab4da2834870362203c848.png_pic_center]

OK， 显示登录信息就是这样了

[d0bc69daec4c4786862d9178bf3edc56.png_pic_center]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/22/893aaebc7bff4cadb0a2d3b738b6e88e.png
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[4904cd3681d84c1fb66bd1dc4764181a.png_pic_center]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/22/00705a7cb7084b358b7833bb1a6bc1c5.png
[d133e8ad309e4d8dbdb9e5820d222113.png_pic_center]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/22/17b478d48f204878b493d6d2d65a7773.png
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