使用JAR作为有效负载的REST POST服务抛出错误'将请求主体写入服务器'

Question

我得到“将请求主体写入服务器时出错;嵌套异常是java.io.IOException：将请求主体写入服务器时出错”使用下面的代码使用带有jar文件作为有效负载的RestTemplate进行POST服务调用

请告诉我这里可能存在的问题

    RestTemplate restTemplate = new RestTemplate();

    SimpleClientHttpRequestFactory requestFactory = new SimpleClientHttpRequestFactory();
    requestFactory.setBufferRequestBody(false);
    restTemplate.setRequestFactory(requestFactory);

    ClassLoader classLoader = getClass().getClassLoader();
    File file = new File(classLoader.getResource("*.jar").getFile());

    HttpEntity<FileSystemResource> requestEntity = new HttpEntity<>(new FileSystemResource(file));
    ResponseEntity<String> response = restTemplate.exchange(url, HttpMethod.POST, requestEntity, String.class);