解决 ajax请求 跨域问题

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错误信息

在前端用ajax 请求后端 接口 时候 出现下面错误时。

Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'null' is therefore not allowed access. The response had HTTP status code 403.

什么是跨域？

简单的说即为浏览器限制访问A站点下的js代码对B站点下的url进行ajax请求。

CORS协议

CORS是一个W3C标准，全称是”跨域资源共享”（Cross-origin resource sharing）

怎么解决?

定义一个Filter　

importorg.springframework.stereotype.Component;importjavax.servlet.*;importjavax.servlet.http.HttpServletResponse;importjava.io.IOException;/***Created by Wuhuahui on 2016/12/13.*/@ComponentPublic class CorsFilter implements Filter{    @Override    Publicvoid init (FilterConfigfilterConfig) throws ServletException{    }    @Override    public void doFilter (ServletRequestservletRequest, ServletResponseservletResponse, FilterChainfilterChain)throws IOException ,ServletException{        HttpServletResponseresponse=(HttpServletResponse)servletResponse;        Stringorigin=(String)servletRequest.getRemoteHost()+":"+servletRequest.getRemotePort();        response.setHeader("Access-Control-Allow-Origin","*");        response.setHeader("Access-Control-Allow-Methods","POST,GET,OPTIONS,DELETE");        response.setHeader("Access-Control-Max-Age","3600");        response.setHeader("Access-Control-Allow-Headers","x-requested-with,Authorization,Origin,Content-Type,Accept");        response.setHeader("Access-Control-Allow-Credentials","true");        filterChain.doFilter(servletRequest,servletResponse);    }    @Override    Public void destroy(){    }}

在web.xml中配置

<filter><filter-name>cors</filter-name><filter-class>top.annwz.base.filter.CorsFilter</filter-class></filter><filter-mapping><filter-name>cors</filter-name><url-pattern>/*</url-pattern></filter-mapping>

脚注

生成一个脚注1.

目录

用 [TOC]来生成目录：

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1. 这里是 脚注 的 内容. ↩