一：新增攔截器：實現HandlerInterceptor介面，並在由配置類(有@Configuration註解)加入該interceptor，並設定攔截路徑

package com.wzp.interceptor;

import com.wzp.domain.User;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

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

public class LoginHandlerInterceptor implements HandlerInterceptor {

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("intercept url:" + request.getRequestURL());
        System.out.println(
 
"intercept uri:" + request.getRequestURI());
        User user = (User) request.getSession().getAttribute("user");
        if (null != user) {
            return true;
        }
        request.setAttribute("flag", "error");
        request.getRequestDispatcher("/login").forward(request, response);
        
 
return false;
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {

    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {

    }
}

package com.wzp.config;

import com.wzp.interceptor.LoginHandlerInterceptor;
import com.wzp.resolver.MyLocaleResolver;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.LocaleResolver;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.ViewControllerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

@Configuration
//@EnableWebMvc// 如果配置了這個，springboot的webMvc將不會自動裝配，也就是說springboot給我們的預設很多web功能將失效，完全有自己接管
public class MyConfig implements WebMvcConfigurer {// 通過實現WebMvcConfigurer來在原來springboot自動化的基礎上進行擴充套件
    
    // 新增攔截器
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        // 除了去登入頁面，其他請求全部攔截
        registry.addInterceptor(new LoginHandlerInterceptor()).addPathPatterns("/**").excludePathPatterns("/", "/index", "/index.html", "/", "/login", "/login.html", "/user/login",
                "/images/*", "/webjars/**");
    }

    
}