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1 前言
請求是任何Web
服務要關注的對象,而請求頭也是其中非常重要的信息。本文將通過代碼講解如何在Spring MVC
項目中獲取請求頭的內容。主要通過兩種方式獲取:
(1)通過註解@RequestHeader
獲取,需要在Controller
中顯式獲取;
(2)通過RequestContextHolder
獲取,可以任何地方獲取。
接下來通過代碼講解。
2 通過註解@RequestHeader獲取
需要在Controller
中顯示使用@RequestHeader
。
2.1 獲取某個請求頭
只獲取其中一個請求頭,相當容易,代碼如下:
@GetMapping("/webSite")
public String webSite(@RequestHeader("webSite")String webSite) {
return "The webSite is " + webSite;
}
這裏獲取的是webSite
這個請求頭,測試如下:
$ curl http://localhost:8088/header/webSite -H 'webSite: www.pkslow.com'
The webSite is www.pkslow.com
我們查看@RequestHeader
的源碼,它還有其它屬性,如下所示:
public @interface RequestHeader {
@AliasFor("name")
String value() default "";
@AliasFor("value")
String name() default "";
boolean required() default true;
String defaultValue() default "\n\t\t\n\t\t\n\ue000\ue001\ue002\n\t\t\t\t\n";
}
2.1.1 屬性required
required
屬性默認爲true
,如果不配置而客戶端沒有傳遞該請求頭,會有報錯。如果配置爲false
且沒有請求頭,值爲null
。代碼如下:
@GetMapping("/webSite-not-required")
public String webSiteNotRequired(@RequestHeader(value = "webSite", required = false)String webSite) {
return "The webSite is " + webSite;
}
測試結果如下:
$ curl http://localhost:8088/header/webSite-not-required -H 'webSite: www.pkslow.com'
The webSite is www.pkslow.com
$ curl http://localhost:8088/header/webSite-not-required
The webSite is null
2.1.2 屬性defaultValue
defaultValue
更容易理解,通過它來設置默認值。如果有傳遞則獲取客戶端傳遞的值,如果沒有傳遞爲默認值。代碼如下:
@GetMapping("/webSite-defaultValue")
public String webSiteDefaultValue(@RequestHeader(value = "webSite", defaultValue = "pkslow.com")String webSite) {
return "The webSite is " + webSite;
}
測試結果如下:
$ curl http://localhost:8088/header/webSite-defaultValue -H 'webSite: www.pkslow.com'
The webSite is www.pkslow.com
$ curl http://localhost:8088/header/webSite-defaultValue
The webSite is pkslow.com
2.2 獲取所有請求頭
註解@RequestHeader
除了可以獲取某個請求頭,還可以一次性獲取所有請求頭,這時不需要指定名字。可以通過Map
、MultiValueMap
和HttpHeaders
來獲取所有請求頭的值,示例代碼如下:
@GetMapping("/allMap")
public Map<String, String> allMap(@RequestHeader Map<String, String> headers) {
return headers;
}
@GetMapping("/allMultiValueMap")
public Map<String, String> allMultiValueMap(@RequestHeader MultiValueMap<String, String> headers) {
return headers.toSingleValueMap();
}
@GetMapping("/allHttpHeaders")
public String allHttpHeaders(@RequestHeader HttpHeaders headers) {
return headers.toString();
}
測試如下:
$ curl http://localhost:8088/header/allMap -H 'Authorization: Basic cGtzbG93OjEyMzQ1Ng==' -H 'webSite: www.pkslow.com'
{"host":"localhost:8088","user-agent":"curl/7.64.1","accept":"*/*","authorization":"Basic cGtzbG93OjEyMzQ1Ng==","website":"www.pkslow.com"}
$ curl http://localhost:8088/header/allMultiValueMap -H 'Authorization: Basic cGtzbG93OjEyMzQ1Ng==' -H 'webSite: www.pkslow.com'
{"host":"localhost:8088","user-agent":"curl/7.64.1","accept":"*/*","authorization":"Basic cGtzbG93OjEyMzQ1Ng==","website":"www.pkslow.com"}
$ curl http://localhost:8088/header/allHttpHeaders -H 'Authorization: Basic cGtzbG93OjEyMzQ1Ng==' -H 'webSite: www.pkslow.com'
[host:"localhost:8088", user-agent:"curl/7.64.1", accept:"*/*", authorization:"Basic cGtzbG93OjEyMzQ1Ng==", website:"www.pkslow.com"]
3 通過RequestContextHolder獲取
通過RequestContextHolder
來獲取則可以在其它層獲取。它先獲取Request
對象,再獲取請求頭。代碼如下:
@GetMapping("/webSite-RequestContextHolder")
public String webSiteRequestContextHolder() {
ServletRequestAttributes requestAttributes = (ServletRequestAttributes)RequestContextHolder.getRequestAttributes();
// get the request
HttpServletRequest request = requestAttributes.getRequest();
return "The webSite is " + request.getHeader("webSite");
}
測試如下:
$ curl http://localhost:8088/header/webSite-RequestContextHolder -H 'webSite: www.pkslow.com'
The webSite is www.pkslow.com
4 總結
以上兩個方法,對於WebFlux
而言,通過註解@RequestHeader
獲取是可行的;通過RequestContextHolder
獲取則不行,可參考【在Spring WebFlux的任何地方獲取Request對象】。
代碼請查看:https://github.com/LarryDpk/pkslow-samples
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