建立一個攔截器

import org.springframework.web.servlet.HandlerInterceptor;

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

/**
 * hander攔截器
 *
 * @author liu
 */
public class LoginHandlerInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        //return true就放行  false就是攔截
        //登入之後，應該有使用者的Session
        Object loginUser = request.getSession().getAttribute("loginUser");
        //沒有登入`
        if (loginUser == null) {
            request.setAttribute("msg", "沒有許可權，請先登入");
            request.getRequestDispatcher("/index.html").forward(request, response);
            return false;
        } else {
            return true;
        }
    }
}
 

登入時傳送一個session，可用於攔截器判斷是否登入

import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.thymeleaf.util.StringUtils;

import javax.servlet.http.HttpSession;

@Controller
public class loginController {

    @RequestMapping("/user/login")
    public String login(@RequestParam("UserName") String userName,
                        @RequestParam("PassWord") String pwd,
                        Model model,
                        HttpSession session) {

        if (!StringUtils.isEmpty(userName) && "123456".equals(pwd)) {
            //登入後傳送一個session，可用於攔截器判斷是否登入
            session.setAttribute("loginUser",userName);
            return "redirect:/dashboard";
        } else {
            model.addAttribute("msg", "使用者名稱或密碼錯誤");
            return "index";
        }
    }
}
 

config檔案配置，新增攔截器

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
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
public class MyMvcConfig implements WebMvcConfigurer {
    //拓展引用，重寫檢視控制器方法
    @Override
    public void addViewControllers(ViewControllerRegistry registry) {
        WebMvcConfigurer.super.addViewControllers(registry);
        registry.addViewController("/").setViewName("index");
        registry.addViewController("/index.html").setViewName("index");
        registry.addViewController("/list").setViewName("list");
        registry.addViewController("/list.html").setViewName("list");
        registry.addViewController("/dashboard").setViewName("dashboard");
        registry.addViewController("/dashboard.html").setViewName("dashboard");
    }


    //自定義的國際化元件就生效了
    @Bean
    public MyLocaleResolver localeResolver(){
        return  new MyLocaleResolver();
    }

    //攔截器，攔截什麼，放行什麼
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(new LoginHandlerInterceptor())
                .addPathPatterns("/**")
                //注意：不要攔截登入請求"/user/login"
                .excludePathPatterns("/index.html", "/","/user/login","/index", "/css/*", "/img/**", "/js/**");
    }
}