解决Feign无法传递HttpServletResponse

场景：前端调用的接口写在portal层，现在有一个下载的场景需要portal层通过feign调用Neams模块后端服务。

解决方法：使用feign原生的Response做返回，再将feign的Response转换成HttpServletResponse

服务提供方

/**
 * 下载接口
 */
@ApiOperation(value = "基础档案下载")
@GetMapping(value = "/download/{beid}")
public void download(HttpServletResponse response,@PathVariable("beid") String beid) throws Exception {
    try{
        eamsBaseRecordService.download(response, beid);
    }catch (Throwable e){
        log.error(e.getMessage());
        throw new RuntimeException(e);
    }
}

调用方

FeignClient

@FeignClient(contextId = "NeamsRemoteClient",
        name = "${nstc.service.neams.hosted-service:neams-service}",
        path = "${nstc.service.neams.context-path:}",
        fallback = RemoteFallback.class
)
public interface NeamsRemoteClient {

    //不需要传 HttpServletResponse
    @ApiOperation(value = "远程文件下载")
    @GetMapping(value = "/neams/eamsbaserecord/download/{beid}")
    Response download(@PathVariable("beid") String beid) throws Exception;
}

App下载附件Controller入口

@GetMapping("/download")
@ApiOperation(value = "App下载附件")
public void download(HttpServletResponse response, @ApiParam(value = "工单ID") @RequestParam String fileId){
    serviceLocator.getG20AppService().downloadFile(response, fileId);
}

Service具体处理

@Override
public void downloadFile(HttpServletResponse response, String fileId) {
    log.info("downloadFile fileId={}", fileId);
    try {
        //feign.Response
        Response download = neamsRemoteClient.download(fileId);
        log.info("downloadFile download={}", download.status()+";"+download.reason());
        feignResp2ServletResp(download, response);
    } catch (Exception e) {
       log.error("downloadFile err：", e);
    }
}

/**
 * 解决Feign无法传递HttpServletResponse
 * @param feignResponse
 * @param response
 * @throws IOException
 */
public static void feignResp2ServletResp(Response feignResponse, HttpServletResponse response) throws IOException {
    Response.Body body = feignResponse.body();
    try (InputStream inputStream = body.asInputStream(); OutputStream outputStream = response.getOutputStream()) {
        response.setHeader(HttpHeaders.CONTENT_DISPOSITION, feignResponse.headers().get(HttpHeaders.CONTENT_DISPOSITION).stream().findFirst().get());
        response.setContentType(feignResponse.headers().get(HttpHeaders.CONTENT_TYPE).stream().findFirst().get());
        IOUtils.copy(inputStream, outputStream);
    }
}