SpringBoot - 攔截器判斷用戶是否登錄後返回界面

1.POM依賴

<!--過濾、監聽、攔截-->

<dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-aop</artifactId>
    </dependency>

2.新建WebConfig

package com.spring.boot.config;
 
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.config.annotation.InterceptorRegistration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
 
@Configuration
public class WebConfig implements WebMvcConfigurer {
 
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
 
        InterceptorRegistration interceptorRegistration = registry.addInterceptor(new MyInterceptor());
        /*同一異常和無界面*/
        interceptorRegistration.excludePathPatterns("/error");
        interceptorRegistration.excludePathPatterns("/login");
//        interceptorRegistration.excludePathPatterns("/**");
//        interceptorRegistration.excludePathPatterns("/index");
        interceptorRegistration.addPathPatterns("/**");

}

@Override
public void addResourceHandlers(ResourceHandlerRegistry registry) {

    //須要配置1：須要告知系統，這是要被當成靜態文件的！
    //第一個方法設置訪問路徑前綴，第二個方法設置資源路徑
    registry.addResourceHandler("/static/**").addResourceLocations("classpath:/static/");
}

private class MyInterceptor implements HandlerInterceptor {

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws IOException {

        System.out.println("在控制器執行前調用 ");
        Object admin = request.getSession().getAttribute("admin");
        if (admin == null) {
            System.out.println("當前用戶未登陸!");
            response.sendRedirect( "/login");
            return false;
        }
        System.out.println("當前用戶已登陸，登陸的用戶名爲： " + admin);
        return true;
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) {
        //controller方法處理完畢後，調用此方法
        System.out.println("在後端控制器執行後調用 ");
    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) {
        //頁面渲染完畢後調用此方法
        System.out.println("整個請求執行完成後調用 ");
    }
}

}

3.須要Controller中重寫login

@RequestMapping(value = "/login")

public String admin(){

    return "login";
}

注：本身稍微梳理一下