package com.boying.common;

import com.boying.common.util.StringUtil;
import org.aspectj.lang.annotation.Aspect;
import org.springframework.stereotype.Component;

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

/**
 * 跨域过滤器
 * @author jitwxs
 * @since 2018/10/16 20:53
 */
@Component
public class CorsFilter implements Filter {
    @Override
    public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {
        HttpServletResponse response = (HttpServletResponse) res;
        HttpServletRequest request = (HttpServletRequest) req;

        // 不使用*，自动适配跨域域名，避免携带Cookie时失效
        String origin = request.getHeader("Origin");
        if(!StringUtil.isNullOrEmpty(origin)) {
            response.setHeader("Access-Control-Allow-Origin", origin);
        }

        // 自适应所有自定义头
        String headers = request.getHeader("Access-Control-Request-Headers");
        if(!StringUtil.isNullOrEmpty(headers)) {
            response.setHeader("Access-Control-Allow-Headers", headers);
            response.setHeader("Access-Control-Expose-Headers", headers);
        }

        // 允许跨域的请求方法类型
        response.setHeader("Access-Control-Allow-Methods", "*");
        // 预检命令（OPTIONS）缓存时间，单位：秒
        response.setHeader("Access-Control-Max-Age", "3600");
        // 明确许可客户端发送Cookie，不允许删除字段即可
        response.setHeader("Access-Control-Allow-Credentials", "true");

        chain.doFilter(request, response);
    }

    @Override
    public void init(FilterConfig filterConfig) {

    }

    @Override
    public void destroy() {
    }

    /*
    注册过滤器：
    @Bean
    public FilterRegistrationBean registerFilter() {
        FilterRegistrationBean<CorsFilter> bean = new FilterRegistrationBean<>();
        bean.addUrlPatterns("/*");
        bean.setFilter(new CorsFilter());
        // 过滤顺序，从小到大依次过滤
        bean.setOrder(Ordered.HIGHEST_PRECEDENCE);
        return bean;
    }
     */
}