【WEB 系列】RestTemplate 之自定义请求头
上一篇介绍了 RestTemplate 的基本使用姿势,在文末提出了一些扩展的高级使用姿势,本篇将主要集中在如何携带自定义的请求头,如设置 User-Agent,携带 Cookie
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借助 SpringBoot 搭建一个 SpringWEB 项目,提供一些用于测试的 REST 服务
2.2.1.RELEASE spring-boot-stater-web
<dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> </dependencies>
为了后续输出的日志更直观,这里设置了一下日志输出格式,在配置文件 application.yml
中,添加
logging: pattern: console: (%msg%n%n){blue}
添加三个接口,分别提供 GET 请求,POST 表单,POST json 对象,然后返回请求头、请求参数、cookie,具体实现逻辑相对简单,也不属于本篇重点,因此不赘述说明
@RestController public class DemoRest { private String getHeaders(HttpServletRequest request) { Enumeration<String> headerNames = request.getHeaderNames(); String name; JSONObject headers = new JSONObject(); while (headerNames.hasMoreElements()) { name = headerNames.nextElement(); headers.put(name, request.getHeader(name)); } return headers.toJSONString(); } private String getParams(HttpServletRequest request) { return JSONObject.toJSONString(request.getParameterMap()); } private String getCookies(HttpServletRequest request) { Cookie[] cookies = request.getCookies(); if (cookies == null || cookies.length == 0) { return ""; } JSONObject ck = new JSONObject(); for (Cookie cookie : cookies) { ck.put(cookie.getName(), cookie.getValue()); } return ck.toJSONString(); } private String buildResult(HttpServletRequest request) { return buildResult(request, null); } private String buildResult(HttpServletRequest request, Object obj) { String params = getParams(request); String headers = getHeaders(request); String cookies = getCookies(request); if (obj != null) { params += " | " + obj; } return "params: " + params + "/nheaders: " + headers + "/ncookies: " + cookies; } @GetMapping(path = "get") public String get(HttpServletRequest request) { return buildResult(request); } @PostMapping(path = "post") public String post(HttpServletRequest request) { return buildResult(request); } @Data @NoArgsConstructor public static class ReqBody implements Serializable { private static final long serialVersionUID = -4536744669004135021L; private String name; private Integer age; } @PostMapping(path = "body") public String postBody(@RequestBody ReqBody body) { HttpServletRequest request = ((ServletRequestAttributes) RequestContextHolder.getRequestAttributes()).getRequest(); return buildResult(request, body); } }
最常见的携带请求头的需求,无非是 referer 校验,user-agent 的防爬以及携带 cookie,使用 RestTemplate 可以借助 HttpHeaders
来处理请求头
前一篇博文介绍了 GET 请求的三种方式,但是 getForObject
/ getForEntity
都不满足我们的场景,这里需要引入 exchange
方法
public void header() { RestTemplate restTemplate = new RestTemplate(); HttpHeaders headers = new HttpHeaders(); headers.set("user-agent", "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/83.0.4103.97 Safari/537.36"); headers.set("cookie", "my_user_id=haha123; UN=1231923;gr_user_id=welcome_yhh;"); // 注意几个请求参数 HttpEntity<String> res = restTemplate .exchange("http://127.0.0.1:8080/get?name=一灰灰&age=20", HttpMethod.GET, new HttpEntity<>(null, headers), String.class); log.info("get with selfDefine header: {}", res); }
exchange 的使用姿势和我们前面介绍的 postForEntity
差不多,只是多了一个指定 HttpMethod 的参数而已
输出结果
(get with selfDefine header: <200,params: {"name":["一灰灰"],"age":["20"]} headers: {"cookie":"my_user_id=haha123; UN=1231923;gr_user_id=welcome_yhh;","host":"127.0.0.1:8080","connection":"keep-alive","accept":"text/plain, application/json, application/*+json, */*","user-agent":"Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/83.0.4103.97 Safari/537.36"} cookies: {"my_user_id":"haha123","UN":"1231923","gr_user_id":"welcome_yhh"},[Content-Type:"text/plain;charset=UTF-8", Content-Length:"447", Date:"Mon, 29 Jun 2020 07:48:49 GMT"]>
post 携带请求头,也可以利用上面的方式实现;当然我们一般直接借助 postForObject/postForEntity
就可以满足需求了
// httpHeaders 和上面的一致,这里省略相关代码 // post 带请求头 MultiValueMap<String, Object> params = new LinkedMultiValueMap<>(); params.add("name", "一灰灰Blog"); params.add("age", 20); String response = restTemplate .postForObject("http://127.0.0.1:8080/post", new HttpEntity<>(params, headers), String.class); log.info("post with selfDefine header: {}", response);
输出结果
(post with selfDefine header: params: {"name":["一灰灰Blog"],"age":["20"]} headers: {"content-length":"338","cookie":"my_user_id=haha123; UN=1231923;gr_user_id=welcome_yhh;","host":"127.0.0.1:8080","content-type":"multipart/form-data;charset=UTF-8;boundary=2VJHo9r6lYgR_WoSBy1FQC40jvBvGtLk7QUaymGg","connection":"keep-alive","accept":"text/plain, application/json, application/*+json, */*","user-agent":"Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/83.0.4103.97 Safari/537.36"} cookies: {"my_user_id":"haha123","UN":"1231923","gr_user_id":"welcome_yhh"}
如果我们可以确定每次发起请求时,都要设置一个自定义的 User-Agent
,每次都使用上面的两种姿势就有点繁琐了,因此我们是可以通过拦截器的方式来添加通用的请求头,这样使用这个 RestTemplate 时,都会携带上请求头
// 借助拦截器的方式来实现塞统一的请求头 ClientHttpRequestInterceptor interceptor = (httpRequest, bytes, execution) -> { httpRequest.getHeaders().set("user-agent", "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/83.0.4103.97 Safari/537.36"); httpRequest.getHeaders().set("cookie", "my_user_id=haha123; UN=1231923;gr_user_id=interceptor;"); return execution.execute(httpRequest, bytes); }; restTemplate.getInterceptors().add(interceptor); response = restTemplate.getForObject("http://127.0.0.1:8080/get?name=一灰灰&age=20", String.class); log.info("get with selfDefine header by Interceptor: {}", response);
上面这个使用姿势比较适用于通用的场景,测试输出
(get with selfDefine header by Interceptor: params: {"name":["一灰灰"],"age":["20"]} headers: {"cookie":"my_user_id=haha123; UN=1231923;gr_user_id=interceptor;","host":"127.0.0.1:8080","connection":"keep-alive","accept":"text/plain, application/json, application/*+json, */*","user-agent":"Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/83.0.4103.97 Safari/537.36"} cookies: {"my_user_id":"haha123","UN":"1231923","gr_user_id":"interceptor"}
在我们使用自定义请求头时,有一个需要特殊重视的地方,HttpHeaders 使用不当,可能导致请求头爆炸
/** * 错误的请求头使用姿势 */ public void errorHeader() { RestTemplate restTemplate = new RestTemplate(); int i = 0; // 为了复用headers,避免每次都创建这个对象,但是在循环中又是通过 add 方式添加请求头,那么请求头会越来越膨胀,最终导致请求超限 // 这种case,要么将add改为set;要么不要在循环中这么干 HttpHeaders headers = new HttpHeaders(); while (++i < 5) { headers.add("user-agent", "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/83.0.4103.97 Safari/537.36"); headers.add("cookie", "my_user_id=haha123; UN=1231923;gr_user_id=welcome_yhh;"); HttpEntity<String> res = restTemplate.exchange("http://127.0.0.1:8080/get?name=一灰灰&age=20", HttpMethod.GET, new HttpEntity<>(null, headers), String.class); log.info("get with selfDefine header: {}", res); } }
上面演示的关键点为
headers.add
方式添加请求头;而不是前面的 set
方式 输出如下,请注意每一次请求过后,请求头膨胀了一次
(get with selfDefine header: <200,params: {"name":["一灰灰"],"age":["20"]} headers: {"cookie":"my_user_id=haha123; UN=1231923;gr_user_id=welcome_yhh;","host":"127.0.0.1:8080","connection":"keep-alive","accept":"text/plain, application/json, application/*+json, */*","user-agent":"Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/83.0.4103.97 Safari/537.36"} cookies: {"my_user_id":"haha123","UN":"1231923","gr_user_id":"welcome_yhh"},[Content-Type:"text/plain;charset=UTF-8", Content-Length:"447", Date:"Mon, 29 Jun 2020 07:48:49 GMT"]> (get with selfDefine header: <200,params: {"name":["一灰灰"],"age":["20"]} headers: {"cookie":"my_user_id=haha123; UN=1231923;gr_user_id=welcome_yhh;; my_user_id=haha123; UN=1231923;gr_user_id=welcome_yhh;","host":"127.0.0.1:8080","connection":"keep-alive","accept":"text/plain, application/json, application/*+json, */*","user-agent":"Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/83.0.4103.97 Safari/537.36"} cookies: {"my_user_id":"haha123","UN":"1231923","gr_user_id":"welcome_yhh"},[Content-Type:"text/plain;charset=UTF-8", Content-Length:"503", Date:"Mon, 29 Jun 2020 07:48:49 GMT"]> (get with selfDefine header: <200,params: {"name":["一灰灰"],"age":["20"]} headers: {"cookie":"my_user_id=haha123; UN=1231923;gr_user_id=welcome_yhh;; my_user_id=haha123; UN=1231923;gr_user_id=welcome_yhh;; my_user_id=haha123; UN=1231923;gr_user_id=welcome_yhh;","host":"127.0.0.1:8080","connection":"keep-alive","accept":"text/plain, application/json, application/*+json, */*","user-agent":"Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/83.0.4103.97 Safari/537.36"} cookies: {"my_user_id":"haha123","UN":"1231923","gr_user_id":"welcome_yhh"},[Content-Type:"text/plain;charset=UTF-8", Content-Length:"559", Date:"Mon, 29 Jun 2020 07:48:49 GMT"]> (get with selfDefine header: <200,params: {"name":["一灰灰"],"age":["20"]} headers: {"cookie":"my_user_id=haha123; UN=1231923;gr_user_id=welcome_yhh;; my_user_id=haha123; UN=1231923;gr_user_id=welcome_yhh;; my_user_id=haha123; UN=1231923;gr_user_id=welcome_yhh;; my_user_id=haha123; UN=1231923;gr_user_id=welcome_yhh;","host":"127.0.0.1:8080","connection":"keep-alive","accept":"text/plain, application/json, application/*+json, */*","user-agent":"Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/83.0.4103.97 Safari/537.36"} cookies: {"my_user_id":"haha123","UN":"1231923","gr_user_id":"welcome_yhh"},[Content-Type:"text/plain;charset=UTF-8", Content-Length:"615", Date:"Mon, 29 Jun 2020 07:48:49 GMT"]>
尽信书则不如,以上内容,纯属一家之言,因个人能力有限,难免有疏漏和错误之处,如发现 bug 或者有更好的建议,欢迎批评指正,不吝感激
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