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
- Get 携带请求头
- Post 携带请求头
- 拦截器方式设置统一请求头
I. 项目搭建
1. 配置
借助 SpringBoot 搭建一个 SpringWEB 项目，提供一些用于测试的 REST 服务
- SpringBoot 版本:
2.2.1.RELEASE - 核心依赖:
spring-boot-stater-web
<dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> </dependencies> 复制代码
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} 复制代码
2. Rest 服务
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); } } 复制代码
II. 使用姿势
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
1. Get 携带请求头
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); } 复制代码
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
重点在于将请求头塞入 HttpEntity
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"]> 复制代码
2. Post 携带请求头
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); 复制代码
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"} 复制代码
3. 拦截器方式
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); 复制代码
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"} 复制代码
4. 请求头错误使用姿势
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); } } 复制代码
上面演示的关键点为
- 希望复用 HttpHeaders
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/pla
