1 前言
请求是任何Web服务要关注的对象,而请求头也是其中非常重要的信息。本文将通过代码讲解如何在Spring MVC项目中获取请求头的内容。主要通过两种方式获取:
(1)通过注解@RequestHeader获取,需要在Controller中显式获取;
(2)通过RequestContextHolder获取,可以任何地方获取。
接下来通过代码讲解。
2 通过注解@RequestHeader获取
需要在Controller中显示使用@RequestHeader。
2.1 获取某个请求头
只获取其中一个请求头,相当容易,代码如下:
@GetMapping("/webSite") public String webSite(@RequestHeader("webSite")String webSite) { return "The webSite is " + webSite; }
这里获取的是webSite这个请求头,测试如下:
$ curl http://localhost:8088/header/webSite -H 'webSite: www.pkslow.com' The webSite is www.pkslow.com
我们查看@RequestHeader的源码,它还有其它属性,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 属性required
required属性默认为true,如果不配置而客户端没有传递该请求头,会有报错。如果配置为false且没有请求头,值为null。代码如下:
@GetMapping("/webSite-not-required") public String webSiteNotRequired(@RequestHeader(value = "webSite", required = false)String webSite) { return "The webSite is " + webSite; }
测试结果如下:
$ 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 属性defaultValue
defaultValue更容易理解,通过它来设置默认值。如果有传递则获取客户端传递的值,如果没有传递为默认值。代码如下:
@GetMapping("/webSite-defaultValue") public String webSiteDefaultValue(@RequestHeader(value = "webSite", defaultValue = "pkslow.com")String webSite) { return "The webSite is " + webSite; }
测试结果如下:
$ 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 获取所有请求头
注解@RequestHeader除了可以获取某个请求头,还可以一次性获取所有请求头,这时不需要指定名字。可以通过Map、MultiValueMap和HttpHeaders来获取所有请求头的值,示例代码如下:
@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(); }
测试如下:
$ 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 通过RequestContextHolder获取
通过RequestContextHolder来获取则可以在其它层获取。它先获取Request对象,再获取请求头。代码如下:
@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"); }
测试如下:
$ curl http://localhost:8088/header/webSite-RequestContextHolder -H 'webSite: www.pkslow.com' The webSite is www.pkslow.com
4 总结
以上两个方法,对于WebFlux而言,通过注解@RequestHeader获取是可行的;通过RequestContextHolder获取则不行,可参考【在Spring WebFlux的任何地方获取Request对象】。
代码请查看:https://github.com/LarryDpk/pkslow-samples
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