重新认识一下跨域问题

package com.chaboshi.www.loginfo;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.OutputStream;
import java.util.concurrent.atomic.AtomicInteger;

@WebFilter("/*")
public class ACrosFilter implements Filter {

    private Logger logger = LoggerFactory.getLogger(ACrosFilter.class);
    private int second=60*60;//
    private AtomicInteger count;

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        count=new AtomicInteger();
        logger.info("跨域拦截器已经启动");
    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {

        HttpServletResponse resp = (HttpServletResponse) response;
        HttpServletRequest rest=(HttpServletRequest)request;
        String origin =null;
        if (null!=rest&&rest.getMethod().equals("OPTIONS")) {
            logger.info("收到预请求{"+rest.getHeader("Origin")+"}请求类型{"+rest.getMethod()+"}");
            resp.setStatus(HttpServletResponse.SC_OK);

        }
        origin = rest.getHeader("Origin");
        // 添加参数，允许任意domain访问
        resp.setHeader("Access-Control-Allow-Origin", origin );

        resp.setHeader("Access-Control-Allow-Methods","PUT,POST,GET,DELETE,OPTIONS");
        resp.setHeader("Access-Control-Max-Age", "0");
        // 被注释都得 Access-Control-Allow-Headers 属性值在测试环境是可以使用的，镜像不可以
        resp.setHeader("Access-Control-Allow-Headers", "Accept,Content-Type,X-Requested-With,accept,Origin,Access-Control-Request-Method,Access-Control-Request-Headers,TOKEN,Authorization,token");//
      
       //跨域允许携带Cookie 前端Ajax配合增加
        // xhrFields: {
       //  withCredentials: true
       //   } 属性   这里注意的是 如果允许跨域Cookie 则Access-Control-Allow-Origin不能为*
        resp.setHeader("Access-Control-Allow-Credentials", "true");
        
        resp.setCharacterEncoding("UTF-8");
        resp.setHeader("Access-Control-Expose-Headers", "*");//响应客户端的头部 允许携带Token 等等

        try {
            chain.doFilter(request, resp);

        } catch (Exception e) {
            response.setContentType("application/json; charset=utf-8");
            response.setCharacterEncoding("UTF-8");
            OutputStream out = resp.getOutputStream();
            String message=e.getMessage();
            out.write(message.getBytes("UTF-8"));
            out.flush();

        }


    }

    @Override
    public void destroy() {
        count=null;
        logger.info(" 跨域拦截器已经销毁");
    }
}