【SpringBoot WEB 系列】RestTemplate 之自定義請求頭

【WEB 系列】RestTemplate 之自定義請求頭

上一篇介紹了 RestTemplate 的基本使用姿勢，在文末提出了一些擴展的高級使用姿勢，本篇將主要集中在如何攜帶自定義的請求頭，如設置 User-Agent，攜帶 Cookie

Get 攜帶請求頭
Post 攜帶請求頭
攔截器方式設置統一請求頭

I. 項目搭建

1. 配置

藉助 SpringBoot 搭建一個 SpringWEB 項目，提供一些用於測試的 REST 服務

SpringBoot 版本: 2.2.1.RELEASE
核心依賴: spring-boot-stater-web

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
</dependencies>

爲了後續輸出的日誌更直觀，這裏設置了一下日誌輸出格式，在配置文件application.yml中，添加

logging:
  pattern:
    console: (%msg%n%n){blue}

2. Rest 服務

添加三個接口，分別提供 GET 請求，POST 表單，POST json 對象，然後返回請求頭、請求參數、cookie，具體實現邏輯相對簡單，也不屬於本篇重點，因此不贅述說明

@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);
    }
}

II. 使用姿勢

最常見的攜帶請求頭的需求，無非是 referer 校驗，user-agent 的防爬以及攜帶 cookie，使用 RestTemplate 可以藉助HttpHeaders來處理請求頭

1. Get 攜帶請求頭

前一篇博文介紹了 GET 請求的三種方式，但是getForObject/getForEntity都不滿足我們的場景，這裏需要引入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;");

        // 注意幾個請求參數
        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 的使用姿勢和我們前面介紹的postForEntity差不多，只是多了一個指定 HttpMethod 的參數而已

重點在於將請求頭塞入 HttpEntity

輸出結果

(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"]>

2. Post 攜帶請求頭

post 攜帶請求頭，也可以利用上面的方式實現；當然我們一般直接藉助postForObject/postForEntity就可以滿足需求了

// httpHeaders 和上面的一致，這裏省略相關代碼
// post 帶請求頭
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);

輸出結果

(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"}

3. 攔截器方式

如果我們可以確定每次發起請求時，都要設置一個自定義的 User-Agent，每次都使用上面的兩種姿勢就有點繁瑣了，因此我們是可以通過攔截器的方式來添加通用的請求頭，這樣使用這個 RestTemplate 時，都會攜帶上請求頭

// 藉助攔截器的方式來實現塞統一的請求頭
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);

上面這個使用姿勢比較適用於通用的場景，測試輸出

(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"}

4. 請求頭錯誤使用姿勢

在我們使用自定義請求頭時，有一個需要特殊重視的地方，HttpHeaders 使用不當，可能導致請求頭爆炸

/**
 * 錯誤的請求頭使用姿勢
 */
public void errorHeader() {
    RestTemplate restTemplate = new RestTemplate();

    int i = 0;
    // 爲了複用headers，避免每次都創建這個對象，但是在循環中又是通過 add 方式添加請求頭，那麼請求頭會越來越膨脹，最終導致請求超限
    // 這種case，要麼將add改爲set；要麼不要在循環中這麼幹
    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);
    }
}

上面演示的關鍵點爲

希望複用 HttpHeaders
headers.add 方式添加請求頭；而不是前面的 set方式

輸出如下，請注意每一次請求過後，請求頭膨脹了一次

(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"]>

II. 其他

0. 項目&系列博文

系列博文

【WEB 系列】RestTemplate 基礎用法小結

源碼

1. 一灰灰 Blog

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【SpringBoot WEB 系列】RestTemplate 之自定義請求頭

I. 項目搭建

1. 配置

2. Rest 服務

II. 使用姿勢

1. Get 攜帶請求頭

2. Post 攜帶請求頭

3. 攔截器方式

4. 請求頭錯誤使用姿勢

II. 其他

0. 項目&系列博文

1. 一灰灰 Blog

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https://yachay.unat.edu.pe/blog/index.php?comment_area=format_blog&comment_component=blog&comment_co

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