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数据缓存
大部分接口应该在响应头中携带 Last-Modified
, ETag
, Vary
, Date
信息,客户端可以在随后请求这些资源的时候,在请求头中使用 If-Modified-Since
, If-None-Match
等请求头来确认资源是否经过修改。
如果资源没有进行过修改,那么就可以响应 304 Not Modified
并且不在响应实体中返回任何内容。
$ curl -i http://api.example.com/#{RESOURCE_URI}
HTTP/1.1 200 OK
Cache-Control: public, max-age=60
Date: Thu, 05 Jul 2012 15:31:30 GMT
Vary: Accept, Authorization
ETag: "644b5b0155e6404a9cc4bd9d8b1ae730"
Last-Modified: Thu, 05 Jul 2012 15:31:30 GMT
Content
$ curl -i http://api.example.com/#{RESOURCE_URI} -H "If-Modified-Since: Thu, 05 Jul 2012 15:31:30 GMT"
HTTP/1.1 304 Not Modified
Cache-Control: public, max-age=60
Date: Thu, 05 Jul 2012 15:31:45 GMT
Vary: Accept, Authorization
Last-Modified: Thu, 05 Jul 2012 15:31:30 GMT
$ curl -i http://api.example.com/#{RESOURCE_URI} -H 'If-None-Match: "644b5b0155e6404a9cc4bd9d8b1ae730"'
HTTP/1.1 304 Not Modified
Cache-Control: public, max-age=60
Date: Thu, 05 Jul 2012 15:31:55 GMT
Vary: Accept, Authorization
ETag: "644b5b0155e6404a9cc4bd9d8b1ae730"
Last-Modified: Thu, 05 Jul 2012 15:31:30 GMT
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