spring boot - Httpcache on springboot -

i have springboot application requests image url display on browser. want cache response using cache-control header.

i use responseentity , set header etag. checked response header in browser , shows :

cache-control:"max-age=31536000, public" content-type:"image/jpeg;charset=utf-8" etag:"db577053a18fa88f62293fbf1bd4b1ee" 

my request have if-none-match header. but, 200 status instead of 304.

here's code

@requestmapping(value = "/getimage", method=requestmethod.get) public responseentity<byte[]> getimage() throws exception {     string url = "www.example.com/image.jpeg";     string etag = getetag(url);      httpheaders headers = new httpheaders();     headers.setcontenttype(new mediatype("image", "jpeg"));     headers.add("cache-control", "max-age=31536000, public");     headers.add("etag", etag);      url imageurl = new url(url);     inputstream = imageurl.openstream();     bufferedimage imbuff = imageio.read(is);     bytearrayoutputstream baos = new bytearrayoutputstream();     imageio.write(imbuff, "jpeg", baos);     byte[] image = baos.tobytearray();      return new responseentity<byte[]>(image, headers, httpstatus.ok); } 

can me?

update

i tried using method described in unable cache images served spring mvc code become :

@requestmapping(value = "/getimage", method=requestmethod.get) public responseentity<byte[]> getimage() throws exception {     string url = "www.example.com/image.jpeg";     string etag = getetag(url);      url imageurl = new url(url);     httpurlconnection httpcon = (httpurlconnection)imageurl.openconnection();     long lastmodified = httpcon.getlastmodified();      httpheaders headers = new httpheaders();     headers.setcontenttype(new mediatype("image", "jpeg"));     headers.add("cache-control", "max-age=31536000, public");     headers.add("etag", etag);     headers.add("last-modified", new date(lastmodified).tostring());      if (webrequest.checknotmodified(etag)) {         return null;     }     inputstream = imageurl.openstream();     bufferedimage imbuff = imageio.read(is);     bytearrayoutputstream baos = new bytearrayoutputstream();     imageio.write(imbuff, "jpeg", baos);     byte[] image = baos.tobytearray();      return new responseentity<byte[]>(image, headers, httpstatus.ok); } 

but 304 status code if change url. checked webrequest.checkisnotmodified(...) either etag , last-modified , return true. did wrong here?

i ended changing code. instead of using webrequest.checknotmodified(etag) manually check last-modified , etag resource (which s3) , compare if-modified-since , if-none-match in request header.

besides, move related http caching in filter.