springboot设置拦截器

1.创建类实现HandlerInterceptor接口

@Component
public class AdminLoginInterceptor implements HandlerInterceptor {

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object o) throws Exception {
        System.out.println("进入拦截器...");
        String uri = request.getRequestURI();
        if (uri.startsWith("/admin") && null == request.getSession().getAttribute("loginUser")) {
            request.getSession().setAttribute("errorMsg", "请登录");
            response.sendRedirect(request.getContextPath() + "/admin/login");
            System.out.println("未登录，拦截成功...");
            return false;
        } else {
            request.getSession().removeAttribute("errorMsg");
            System.out.println("已登录，放行...");
            return true;
        }
    }

    @Override
    public void postHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, ModelAndView modelAndView) throws Exception {
    }

    @Override
    public void afterCompletion(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, Exception e) throws Exception {

    }

preHandle：在业务处理器处理请求之前被调用。预处理，可以进行编码、安全控制、权限校验等处理。postHandle：在业务处理器处理请求执行完成后，生成视图之前执行。afterCompletion：在DispatcherServlet完全处理完请求后被调用，可用于清理资源等，返回处理（已经渲染了页面）。

2. 新建配置类，该类需要实WebMvcConfigurer接口

@Configuration
public class NeeBeeMallWebMvcConfigurer implements WebMvcConfigurer {

    @Autowired
    private AdminLoginInterceptor adminLoginInterceptor;
    
    public void addInterceptors(InterceptorRegistry registry) {
        // 添加一个拦截器，拦截以/admin为前缀的URL路径（后台登录拦截）
        registry.addInterceptor(adminLoginInterceptor)
                .addPathPatterns("/admin/**")
                .excludePathPatterns("/admin/login")
                .excludePathPatterns("/admin/dist/**")
                .excludePathPatterns("/admin/plugins/**");
    }
}

addPathPatterns()方法和excludePathPatterns()两个方法，它们分别是添加路径拦截规则和排除路径拦截规则