<p>如果我们访问的资源是不需要授权的，也就是在HTTP请求头中不包含 authentication 头那么以上做法就足够了。但是如果该资源是需要权限验证的，那么这个时候跨域请求的预检测 <strong> option 请求，由于不会携带身份信息而被拒绝 </strong> 。浏览器会报出401错误。</p>    <p>前几天的文章 <a href="http://www.open-open.com/lib/view/open1463878352785.html" rel="nofollow,noindex">Spring通过CROS协议解决跨域问题</a> 中提到了如何解决跨域问题的基本思路,解决了跨域请求时浏览器403错误。</p>    <pre>  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  </pre>    <p>401错误信息如下：</p>    <pre>  Failed to load resource:  the server responded with a status of 401 (Unauthorized)  XMLHttpRequest cannot load http://localhost/api/test.  Response for preflight has invalid HTTP status code 401  </pre>    <p>既然知道了问题的原因，答案也就很容易得出： 对需要进行跨域请求的资源（api），当服务端检测到是 OPTONS 请求时候统统放行，给出HTTP.OK(200)的状态和必要的响应头，哪怕它是不带身份信息的 。</p>    <p>这个问题既可以通过编写对应的后端代码实现，也可以通过设置服务器配置文件实现。也就是如何设置响应头和返回200状态码的办法了。</p>    <h2>Spring+Shrio的解决方案</h2>    <p>shiro中可以在自己实现的身份验证filter中加入以下代码：</p>    <pre>  @Override    protected boolean preHandle(ServletRequest servletRequest, ServletResponse servletResponse) throws Exception {        HttpServletRequest request = (HttpServletRequest) servletRequest;        HttpServletResponse response = (HttpServletResponse) servletResponse;        if(request.getMethod().equals(RequestMethod.OPTIONS.name()))        {            response.setStatus(HttpStatus.OK.value());            return false;        }        return super.preHandle(request, response);    }  </pre>    <p>shiro中AccessControlFilter提供了访问控制的基础功能；比如是否允许访问/当访问拒绝时如何处理等，也是我们一般自定义权限验证时候的一个父类，我们通过重写他的 onPreHandle 方法判断是否是 option 请求，如果是则设置相应状态，（响应头已经在之前文章中通过filter配置过了）返回false表示该拦截器实例已经处理了，将直接返回即可。</p>    <h2>Tomcat配置</h2>    <p>需要修改tomcat的全局web.xml文件在 CATALINA_HOME/conf 下，加入以下配置。</p>    <pre>  <filter>         <filter-name>CorsFilter</filter-name>         <filter-class>org.apache.catalina.filters.CorsFilter</filter-class>       </filter>       <filter-mapping>         <filter-name>CorsFilter</filter-name>         <url-pattern>/*</url-pattern>       </filter-mapping>  </pre>    <h2>Nginx配置</h2>    <pre>  add_header 'Access-Control-Allow-Methods' 'GET,OPTIONS,PUT,DELETE' always;  add_header 'Access-Control-Allow-Credentials' 'true' always;  add_header 'Access-Control-Allow-Origin' '$http_origin' always;  add_header 'Access-Control-Allow-Headers' 'Authorization,DNT,User-Agent,Keep-Alive,Content-Type,accept,origin,X-Requested-With' always;    if ($request_method = OPTIONS ) {      return 200;  }  </pre>    <h2>Apache配置</h2>    <pre>  Header always set Access-Control-Allow-Origin "http://waffle"  Header always set Access-Control-Allow-Methods "POST, GET, OPTIONS"  Header always set Access-Control-Allow-Credentials "true"  Header always set Access-Control-Allow-Headers "Authorization,DNT,User-Agent,Keep-Alive,Content-Type,accept,origin,X-Requested-With"    RewriteCond %{REQUEST_METHOD} OPTIONS  RewriteRule ^(.*)$ $1 [R=200,L]  </pre>    <h2>js请求示例</h2>    <p>请求时候需要加上 Authorization 和 Content-Type 头。</p>    <pre>  $http({    method: 'POST',    url: scope.webdav.url,    withCredentials: true,    headers: {      Authorization: 'Basic ' + btoa(user + ':' + password),      'Content-Type': 'application/vnd.google-earth.kml+xml; charset=utf-8'    },    data: getKml()  })  </pre>    <p>参考文章： <a href="/misc/goto?guid=4959673493200095131" rel="nofollow,noindex">http://www.jujens.eu/posts/en/2015/Jun/27/webdav-options/</a></p>    <p> </p>    <p>来自： <a href="/misc/goto?guid=4959673493287354045" rel="nofollow">http://blog.kbiao.me/2016/05/21/CROS实现跨域时授权问题（401错误）的解决/</a></p>    <p> </p>