使用Amazon SP-API SDK提供的Java代码，可以获取报告文件。示例如下：

//设置访问密钥信息
AWSStaticCredentialsProvider credentialsProvider = new AWSStaticCredentialsProvider(
        new BasicAWSCredentials(accessKey, secretKey));
//创建报告API客户端
AmazonS3ClientBuilder builder = AmazonS3ClientBuilder.standard()
        .withCredentials(credentialsProvider)
        .withRegion(region);
AmazonS3 s3Client = builder.build();

//设置报告的请求参数
GetReportRequest request = new GetReportRequest()
        .withReportId(reportId)
        .withReportDocumentStream(responseBody);

//获取报告文件
GetReportResult result = marketplaceWebService.getReport(request);