使用RestTemplate 调用远程接口上传文件方式

import org.springframework.core.io.InputStreamResource; 
import java.io.InputStream; 
public class CommonInputStreamResource extends InputStreamResource {
    private long length;
    private String fileName; 
    public CommonInputStreamResource(InputStream inputStream, long length, String fileName) {
        super(inputStream);
        this.length = length;
        this.fileName = fileName;
    }
 
    /**
     * 覆写父类方法
     * 如果不重写这个方法，并且文件有一定大小，那么服务端会出现异常
     * {@code The multi-part request contained parameter data (excluding uploaded files) that exceeded}
     */
    @Override
    public String getFilename() {
        return fileName;
    }
 
    /**
     * 覆写父类 contentLength 方法
     * 因为 {@link org.springframework.core.io.AbstractResource#contentLength()}方法会重新读取一遍文件，
     * 而上传文件时，restTemplate 会通过这个方法获取大小。然后当真正需要读取内容的时候，发现已经读完，会报如下错误。
     */
    @Override
    public long contentLength() {
        long estimate = length;
        return estimate == 0 ? 1 : estimate;
    }
 
    public void setLength(long length) {
        this.length = length;
    }
 
    public void setFileName(String fileName) {
        this.fileName = fileName;
    }
}

try{
    String applySeqNo = "123456";
    String cookie="654321";
    File file=new File("E:\\1.rar");
    FileInputStream fileInputStream=new FileInputStream(file);
 
    //请求头设置为MediaType.MULTIPART_FORM_DATA类型
    HttpHeaders requestHeaders = new HttpHeaders();
    requestHeaders.setContentType(MediaType.MULTIPART_FORM_DATA);
    
    //构建请求体
    MultiValueMap<String, Object> requestBody = new LinkedMultiValueMap<>();
    CommonInputStreamResource commonInputStreamResource = null;
    try {
        commonInputStreamResource = new CommonInputStreamResource(fileInputStream,file.length(),file.getName());
    } catch (Exception e) { 
        log.error("文件输入流转换错误",e);
    }
    requestBody.add("cookie", cookie);
    requestBody.add("seqNoFile", applySeqNo);
    requestBody.add("file",commonInputStreamResource);
    HttpEntity<MultiValueMap> requestEntity = new HttpEntity<MultiValueMap>(requestBody, requestHeaders);
    
    //直接调用远程接口
    ResponseEntity<String> responseEntity = restTemplate.postForEntity("http://xxx.xxx.xxx.xxx:8080/test/upload",requestEntity, String.class);
    System.out.println("返回结果："+responseEntity.getBody())
}catch (Exception e){
    log.error("远程调用出现异常：", e);
}

@Component
@FeignClient(name = "taxRecodes", url = "${spider.url}", qualifier = "TaxRecodeFeignClient",fallback = TaxRecodeFallBack.class)
public interface TaxRecodeFeignClient {    
    /**
     * 单证申请-合同信息表附件上传
     */
    @PostMapping(value = "/attachFile/upload",consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
    String attachFileUpload(MultiValueMap<String, Object> multiValueMap);
}

@PostMapping("/upload")
public void upload(){
    try {
        File file=new File("E:\\1.rar");
        FileInputStream fileInputStream=new FileInputStream(file); 
        CommonInputStreamResource commonInputStreamResource = null;
        try {
            commonInputStreamResource = new CommonInputStreamResource(fileInputStream,fileInputStream.available(),file.getName());
        } catch (Exception e) {
            log.error("文件输入流转换错误:",e);
        } 
        MultiValueMap<String, Object> dto=new LinkedMultiValueMap<String, Object>();
        dto.add("cookie","xxx");
        dto.add("file",commonInputStreamResource);
        dto.add("seqNoFile","xxx");
 
        String returnInfo = taxRecodeFeignClient.attachFileUpload(dto);
        JSONObject returnInfoJsonObject = JSONObject.parseObject(returnInfo);
    }catch (Exception e){
        log.error("异常：",e);
    }
}

// 获取第三方的authorization
String auth= OAuthContentHelper.getAuthorizationHeader();
HttpHeaders requestHeader=new HttpHeaders();
// 将获取到的authorization添加到请求头
requestHeader.add(AuthConstants.AUTHORIZATION_HEADER,auth);
// 构建请求实体
HttpEntity<Object> requestEntity=new HttpEntity(requestParam,requestHeaders);
// 使用restTemplate调用第三方接口
restTemplate.exchage(url,HttpMethod.POST,requestEntity,responseClass);