springboot redis 缓存跨域丢失问题

对于前后端分离的项目，在开发阶段经常会遇到跨域的问题。

1.首先，对于后台的处理方式，第一种是用 @CrossOrigin 注解，@crossorigin是后端SpringMVC框架（需4.2版本以上）Controller层的一个注解，这个注解是用在控制器方法上的，但这种方式不能做到统一跨域处理

@CrossOrigin(origins = "http://localhost:3000")
@RequestMapping(method = RequestMethod.GET)
List<User> getList() {
    return Lists.newArrayList(userdb.asMap().values());
}

2. 第二种方式是 构建一个拦截器

import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.stereotype.Component;

public class SimpleCORSFilter implements Filter {

    public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {

        HttpServletResponse response = (HttpServletResponse) res;
        HttpServletRequest request=  (HttpServletRequest)req;
        response.setHeader("Access-Control-Allow-Credentials","true");//允许跨域加载
        response.setHeader("Access-Control-Allow-Origin", request.getHeader("Origin"));
        response.setHeader("Access-Control-Allow-Methods", "POST, GET, OPTIONS, DELETE");
        response.setHeader("Access-Control-Max-Age", "");
        response.setHeader("Access-Control-Allow-Headers", "x-requested-with");//ajax请求
        chain.doFilter(req, res);
    }

    public void init(FilterConfig filterConfig) {
    }

    public void destroy() {}

}

3.当然，前端ajax请求时，也可以做相应的处理，关键代码 crossDomain: true, xhrFields: { withCredentials: true }

$.ajax({

             type: "POST",
             url: window.ServiceUrl+"/custom/clientLogin",
             crossDomain: true,
             xhrFields: { withCredentials: true },
             data: {username:loginName,password:password},
             dataType : "json",
             success: function(respMsg){
                       //正常操作
             },
             error:function(){
                 //异常操作
             }
         });

4.如果上述方法都不行，可以检查一下cookie的domain和path属性：这里引用一下大佬的章

https://blog.csdn.net/zhouziyu2011/article/details/61200943