package com.dingwen.lir.filter;

import lombok.extern.slf4j.Slf4j;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import java.util.Arrays;

/**
 *  在請求到達(dá)之前對 request 進(jìn)行修改
 *
 * @author dingwen
 * 2021.04.30 14:54
 */
@Slf4j
public class RequestWrapper extends HttpServletRequestWrapper {
    public RequestWrapper(HttpServletRequest request) {
        super(request);
        log.info("RequestWrapper");
    }

    @Override
    public String getParameter(String name) {
        // 可以對請求參數(shù)進(jìn)行過濾
        return super.getParameter(name);
    }

    @Override
    public String[] getParameterValues(String name) {
        // 對請求參數(shù)值進(jìn)行過濾
//        String[] values =super.getRequest().getParameterValues(name);
//        return super.getParameterValues(name);
        return "t e s t".split(" ");
    }


}

package com.dingwen.lir.filter;

import lombok.extern.slf4j.Slf4j;
import org.springframework.web.filter.OncePerRequestFilter;

import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Arrays;

/**
 * 請求過濾器
 * OncePerRequestFilter:
 * OncePerRequestFilter，顧名思義，它能夠確保在一次請求中只通過一次filter.
 * 大家常識上都認(rèn)為，一次請求本來就只filter一次，為什么還要由此特別限定呢，往往我們的常識和實(shí)際的實(shí)現(xiàn)并不真的一樣，經(jīng)過一番資料的查閱，此方法是為了兼容不同的web container，
 * 也就是說并不是所有的container都入我們期望的只過濾一次，servlet版本不同，執(zhí)行過程也不同，
 * 因此，為了兼容各種不同運(yùn)行環(huán)境和版本，默認(rèn)filter繼承OncePerRequestFilter是一個比較穩(wěn)妥的選擇。
 *
 * @author dingwen
 * 2021.04.30 15:59
 */
@Slf4j
public class RequestFilter extends OncePerRequestFilter {


    @Override
    public void destroy() {
        super.destroy();
        log.info("RequestFilter destroy");
    }

    /*
            OncePerRequestFilter.doFilter方法中通過request.getAttribute判斷當(dāng)前過濾器是否已執(zhí)行
            若未執(zhí)行過，則調(diào)用doFilterInternal方法，交由其子類實(shí)現(xiàn)
        */
    @Override
    protected void doFilterInternal(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, FilterChain filterChain) throws ServletException, IOException {
        try {
            RequestWrapper requestWrapper = new RequestWrapper(httpServletRequest);
            filterChain.doFilter(requestWrapper, httpServletResponse);
            log.info("RequestFilter");
            log.info(Arrays.toString(requestWrapper.getParameterValues("name")));
        } catch (Exception exception) {
            httpServletResponse.setCharacterEncoding("utf-8");
            httpServletResponse.setContentType("application/json; charset=utf-8");
            PrintWriter writer = httpServletResponse.getWriter();
            writer.write(exception.toString());
        }
    }
}

package com.dingwen.lir.configuration;

import com.dingwen.lir.filter.RequestFilter;
import com.dingwen.lir.filter.RequestWrapper;
import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import javax.servlet.Filter;

/**
 * 過濾器配置類
 *
 * @author dingwen
 * 2021.04.30 16:10
 */
@Configuration
public class FilterConfig {

    @Bean
    public RequestFilter requestFilter(){
        return new RequestFilter();
    }
    @Bean
    public FilterRegistrationBean<RequestFilter> registrationBean() {
        FilterRegistrationBean<RequestFilter> registrationBean = new FilterRegistrationBean<>();
        registrationBean.setFilter(requestFilter());
        registrationBean.addUrlPatterns("/filter/*");
        registrationBean.setName("RequestFilter");
        //過濾器的級別，值越小級別越高越先執(zhí)行
        registrationBean.setOrder(1);
        return registrationBean;
    }
}

package com.dingwen.lir.interceptor;

import com.dingwen.lir.entity.User;
import org.springframework.stereotype.Component;
import org.springframework.util.ObjectUtils;
import org.springframework.web.servlet.HandlerInterceptor;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

/**
 * 登錄攔截
 *
 * @author dingwen
 * 2021.04.25 13:50
 */
@Component
public class PageInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        User user = (User)request.getSession().getAttribute("user");
        if (!ObjectUtils.isEmpty(user)) {
            return true;
        } else {
            // 不管是轉(zhuǎn)發(fā)還是重定向，必須返回false。否則出現(xiàn)多次提交響應(yīng)的錯誤
            redirect(request, response);
            return false;
        }
    }

    /*
     * 對于請求是ajax請求重定向問題的處理方法
     * @param request
     * @param response
     *
     */
    public void redirect(HttpServletRequest request, HttpServletResponse response) throws IOException {

        if("XMLHttpRequest".equals(request.getHeader("X-Requested-With"))){// ajax
            //獲取當(dāng)前請求的路徑
            response.setHeader("Access-Control-Expose-Headers", "REDIRECT,CONTENT_PATH");
            //告訴ajax我是重定向
            response.setHeader("REDIRECT", "REDIRECT");
            //告訴ajax我重定向的路徑
            StringBuffer url = request.getRequestURL();
            String contextPath = request.getContextPath();
            response.setHeader("CONTENT_PATH", url.replace(url.indexOf(contextPath) + contextPath.length(), url.length(), "/").toString());
        }else{// http
            response.sendRedirect( "/page/login");
        }

        response.getWriter().write(403);
        response.setStatus(HttpServletResponse.SC_FORBIDDEN);
    }
}

package com.dingwen.lir.configuration;

import com.dingwen.lir.interceptor.PageInterceptor;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.ViewControllerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

/**
 * mvc 控制器配置
 * MyWebMvcConfigurer: Springboot2.x以后版本使用
 *
 * @author dingwen
 * 2021.04.26 17:52
 */
@Configuration
public class MyWebMvcConfigurer implements WebMvcConfigurer {

    /*
     * 攔截器依賴于Spring容器，此處攔截了所有，需要對靜態(tài)資源進(jìn)行放行
     */
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        // 攔截器默認(rèn)的執(zhí)行順序，就是它的注冊順序，也可以通過Order手動設(shè)置控制，值越小越先執(zhí)行。
//        registry.addInterceptor(new PageInterceptor()).addPathPatterns("/**").order()
        registry.addInterceptor(new PageInterceptor()).addPathPatterns("/**")
                .excludePathPatterns("/page/login", "/user/login","/page/ajax","/static/**");
    }


    /*
     * 不要要寫控制器即可完成頁面跳轉(zhuǎn)訪問
     * @param registry
     */
    @Override
    public void addViewControllers(ViewControllerRegistry registry) {
        registry.addViewController("/page/ajax").setViewName("ajax");
    }


    /*
     * 自定義靜態(tài)資源映射
        Spring Boot 默認(rèn)為我們提供了靜態(tài)資源映射：
                classpath:/META-INF/resources
                classpath:/resources
                classpath:/static
                classpath:/public
              優(yōu)先級：META-INF/resources > resources > static > public
     * @param registry
     *
     */
//    @Override
//    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("/static/**").addResourceLocations("classpath:/static/");
        registry.addResourceHandler("/static/**").addResourceLocations("file:E:/static/");
//    }
}

 /*
     * 攔截器依賴于Spring容器，此處攔截了所有，需要對靜態(tài)資源進(jìn)行放行
     */
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(new PageInterceptor()).addPathPatterns("/**")
                .excludePathPatterns("/page/login", "/user/login","/page/ajax","/static/**");
    }

spring:
  mvc:
    static-path-pattern: /static/**

// 前端處理
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>AJAX</title>
    <script src="https://code.jquery.com/jquery-3.0.0.min.js"></script>
</head>
<body>
    <button>USER</button>
</body>
</html>

<script>
    $.ajaxSetup({
        complete:function(xhr,status){
            //攔截器實(shí)現(xiàn)超時跳轉(zhuǎn)到登錄頁面
            let win = window;
            // 通過xhr取得響應(yīng)頭
            let REDIRECT = xhr.getResponseHeader("REDIRECT");
            //如果響應(yīng)頭中包含 REDIRECT 則說明是攔截器返回的需要重定向的請求
            if (REDIRECT === "REDIRECT")
            {
                while (win !== win.top)
                {
                    win = win.top;
                }
                win.location.href = xhr.getResponseHeader("CONTEXTPATH");
            }
        }
    });
    $("button").click(function(){
        $.get("/page/user", function(result){
            $("div").html(result);
        });
    });
</script>