如何用Java WebClient或RestTemplate实现指定cURL请求？

原始请求参考 #

cURL示例 #

curl --location --request PUT '[url]' \
--header 'authorization: Bearer [token]' \
--form 'fileData="[json]"' \
--form 'file=@"/C:/path/file.json"'

原始HTTP请求 #

PUT [url]
authorization: Bearer [token]
User-Agent: PostmanRuntime/7.29.2
Accept: */*
Cache-Control: no-cache
Host: [host]
Accept-Encoding: gzip, deflate, br
Connection: keep-alive
Content-Type: multipart/form-data; boundary=--------------------------821418838150769919184719
Content-Length: 121986
 
----------------------------821418838150769919184719
Content-Disposition: form-data; name="fileData"
[json]
----------------------------821418838150769919184719
Content-Disposition: form-data; name="file"; filename="file.json"
<file.json>
----------------------------821418838150769919184719--
 
HTTP/1.1 200 OK
Date: Sat, 27 Aug 2022 01:33:15 GMT
Content-Type: application/json; charset=utf-8
Transfer-Encoding: chunked
Connection: keep-alive
Content-Encoding: br
Vary: Accept-Encoding
Request-Context: appId=cid-v1:55ff528b-00c0-4656-b479-7f1d61e8f50b
Strict-Transport-Security: max-age=86400; includeSubDomains; preload
 
[json response]

RestTemplate实现代码 #

直接构建multipart请求体，设置好授权头即可，框架会自动处理multipart的boundary：

import org.springframework.core.io.FileSystemResource;
import org.springframework.http.HttpEntity;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpMethod;
import org.springframework.http.MediaType;
import org.springframework.util.LinkedMultiValueMap;
import org.springframework.util.MultiValueMap;
import org.springframework.web.client.RestTemplate;

import java.io.File;

public class RestTemplateDemo {
    public static void main(String[] args) {
        // 替换成实际参数
        String targetUrl = "[你的请求URL]";
        String bearerToken = "[你的Bearer令牌]";
        String fileDataJsonStr = "[你的JSON字符串内容]";
        File targetFile = new File("C:/path/file.json");

        // 构建请求头
        HttpHeaders headers = new HttpHeaders();
        headers.setBearerAuth(bearerToken);
        headers.setContentType(MediaType.MULTIPART_FORM_DATA);

        // 组装multipart表单数据
        MultiValueMap<String, Object> formData = new LinkedMultiValueMap<>();
        formData.add("fileData", fileDataJsonStr);
        formData.add("file", new FileSystemResource(targetFile));

        // 发送PUT请求
        RestTemplate restTemplate = new RestTemplate();
        String responseBody = restTemplate.exchange(
                targetUrl,
                HttpMethod.PUT,
                new HttpEntity<>(formData, headers),
                String.class
        ).getBody();

        System.out.println(responseBody);
    }
}

WebClient实现代码 #

响应式方式的实现，同样处理multipart表单和授权头：

import org.springframework.core.io.FileSystemResource;
import org.springframework.http.HttpHeaders;
import org.springframework.http.MediaType;
import org.springframework.web.reactive.function.BodyInserters;
import org.springframework.web.reactive.function.client.WebClient;

import java.io.File;

public class WebClientDemo {
    public static void main(String[] args) {
        // 替换成实际参数
        String targetUrl = "[你的请求URL]";
        String bearerToken = "[你的Bearer令牌]";
        String fileDataJsonStr = "[你的JSON字符串内容]";
        File targetFile = new File("C:/path/file.json");

        WebClient webClient = WebClient.builder().build();

        // 发送PUT请求，同步获取结果（异步场景可去掉block()）
        String responseBody = webClient.put()
                .uri(targetUrl)
                .header(HttpHeaders.AUTHORIZATION, "Bearer " + bearerToken)
                .contentType(MediaType.MULTIPART_FORM_DATA)
                .body(BodyInserters.fromMultipartData(
                        "fileData", fileDataJsonStr,
                        "file", new FileSystemResource(targetFile)
                ))
                .retrieve()
                .bodyToMono(String.class)
                .block();

        System.out.println(responseBody);
    }
}

注意事项 #

• 如果fileData是Java对象，需要先转成JSON字符串，比如用Jackson的ObjectMapper：new ObjectMapper().writeValueAsString(yourObject)
• 不要手动设置multipart的boundary，框架会自动生成并匹配请求体
• 确保本地文件路径正确，程序有读取文件的权限

内容的提问来源于stack exchange，提问作者Tom D