S3图片跨域请求

先修改bucket跨域相关设置。

Request 发送Origin 这个header

Response返回Vary这个header。

HTTP/1.1 200 OK
x-amz-id-2: /I5dU6Px2xMubgiu8mxzUheMdnlHf7M9UPNAs0K1VY+MzUPGBupdFVbhEEnxrP5A
x-amz-request-id: F35821F96B2F4B2F
Date: Mon, 25 May 2015 08:33:19 GMT
Access-Control-Allow-Origin: *
Access-Control-Allow-Methods: GET
Access-Control-Max-Age: 3000
Vary: Origin, Access-Control-Request-Headers, Access-Control-Request-Method
x-amz-version-id: S4ykWmm.nqZesRo9HLAFEWjsuiYrAp7I
Content-Encoding: gzip
Cache-Control: max-age=259200, public
Last-Modified: Mon, 25 May 2015 06:39:34 GMT
ETag: "06c91a9ce260f8e0e08914954181be2a"
Accept-Ranges: bytes
Content-Type: image/png
Content-Length: 7585

Server: AmazonS3

Origin 为null的请求有问题， chrome某些版本有bug。