SpringBoot 拦截器

拦截器实现的几个步骤

• 1、编写一个拦截器实现HandlerInterceptor接口
• 2、拦截器注册到容器中（实现WebMvcConfigurer）
• 3、指定拦截规则【如果是拦截所有，静态资源也会被拦截】

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一、编写一个拦截器实现HandlerInterceptor接口

package com.atguigu.admin.interceptor;

import lombok.extern.slf4j.Slf4j;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

/**
 * 拦截器：做登录检查
 *
 * 拦截器什么时候工作？
 *              1、配置好拦截器要拦截哪些请求
 *              2、把拦截器的配置放置在容器中
 *
 * @author LunarYouI
 * @create 2021-04-12 19:04
 */
@Slf4j
public class LoginInterceptor implements HandlerInterceptor {
    /**
     * 目标方法执行之前
     *
     * @param request
     * @param response
     * @param handler
     * @return
     * @throws Exception
     */
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        //查看拦截了哪些
        String requestURI = request.getRequestURI();
        log.info("preHandle拦截的请求路径是{}",requestURI);

        //执行之前 登录检查逻辑
        HttpSession session = request.getSession();
        Object loginUser = session.getAttribute("loginUser");
        if (loginUser!=null) {
            //return true：为true放行
            return true;
        }

        //拦截住了给提示信息“未登录“并且转发到登录页面
        request.setAttribute("msg","未登录！");
        request.getRequestDispatcher("/").forward(request,response);
        //return false：为flase不放行
        return false;
    }

    /**
     * 目标方法完成以后
     *
     * @param request
     * @param response
     * @param handler
     * @param modelAndView
     * @throws Exception
     */
    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        log.info("postHandle执行{}",modelAndView);
    }

    /**
     * 页面渲染以后
     *
     * @param request
     * @param response
     * @param handler
     * @param ex
     * @throws Exception
     */
    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        log.info("afterCompletion执行异常{}",ex);
    }
}

二、拦截器注册到容器中

package com.atguigu.admin.config;

import com.atguigu.admin.interceptor.LoginInterceptor;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

/**
 * @author LunarYouI
 * @create 2021-04-12 19:12
 */

/**
 * 拦截器实现的几个步骤
 *  1、编写一个拦截器实现HandlerInterceptor接口
 *  2、拦截器注册到容器中（实现WebMvcConfigurer）
 *  3、指定拦截规则【如果是拦截所有，静态资源也会被拦截】
 */
@Configuration
//所有定制web功能的都需要实现WebMvcConfigurer接口
public class AdminWebConfig implements WebMvcConfigurer {
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        /**
         * addInterceptor       添加一个拦截器
         * addPathPatterns      要拦截哪些路径？/**拦截所有，包括静态资源
         * excludePathPatterns  放行哪些？
         */
        registry.addInterceptor(new LoginInterceptor())
        .addPathPatterns("/**")
        .excludePathPatterns("/","/login","/css/**","/fonts/**","/images/**","/js/**");
    }
}

如果嫌上面放行静态麻烦的话 可以给个访问静态资源的前缀，那么就可以直接写/*/**就可以放行所有静态资源

#配置访问静态资源的前缀路径
#spring.mvc.static-path-pattern=/static/**