廢話不多說，直接上程式碼，相信都能看的懂
一共兩布，第一步，建立Interceptor攔截

package com.cy.example.config;

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

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.servlet.HandlerInterceptor;
import
 
 org.springframework.web.servlet.ModelAndView;

public class LoginInterceptor implements HandlerInterceptor {

    private Logger logger = LoggerFactory.getLogger(LoginInterceptor.class);

    public void postHandle(HttpServletRequest request,
            HttpServletResponse response, Object handler,
            ModelAndView modelAndView) throws
 
 Exception {
        // TODO Auto-generated method stub

    }

    public void afterCompletion(HttpServletRequest request,
            HttpServletResponse response, Object handler, Exception ex)
            throws Exception {
        // TODO Auto-generated method stub

    }

    public boolean preHandle
 
(HttpServletRequest request,
            HttpServletResponse response, Object handler) throws Exception {
        // TODO Auto-generated method stub
        //獲取session
        HttpSession session = request.getSession(true);
        logger.info("----進入登入攔截器--url："+request.getServletPath()+"-----");
        if(session.getAttribute(WebConfig.LOGIN_USER) == null){
            logger.info("------跳轉到login頁面-----");
            response.sendRedirect(request.getContextPath()+"/index");
            return false;
        }else{
            session.setAttribute(WebConfig.LOGIN_USER, session.getAttribute(WebConfig.LOGIN_USER));
            return true;
        }
    }

}

第二步，註冊建立的攔截器

package com.cy.example.config;

import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.DefaultServletHandlerConfigurer;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;

@Configuration
public class WebConfig extends WebMvcConfigurerAdapter {

    public static String LOGIN_USER = "loginUser";

    public WebConfig() {
        super();
    }
    //因為新加了攔截器，這裡需要重新設定資源地址
    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("/static/**").addResourceLocations(
                "classpath:/static/");
        registry.addResourceHandler("/templates/**").addResourceLocations(
                "classpath:/templates/");

        super.addResourceHandlers(registry);
    }

    @Override
    public void configureDefaultServletHandling(
            DefaultServletHandlerConfigurer configurer) {
        configurer.enable();
    }

    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        // 攔截規則：除了login，其他都攔截判斷,excludePathPatterns是排除攔截的路徑，一個是登入驗證地址，一個是登入頁
        registry.addInterceptor(new
LoginInterceptor()).addPathPatterns("/**").excludePathPatterns("/index","/system/user/validate");
        super.addInterceptors(registry);
    }

}