如何在下载前获得pdf的字节？- 圣杯

Question

我可以从这里下载pdf文件 AWS我可以从AWS下载pdf文件，下载工作正常，但我需要在下载前获得字节。

        String awsBucket = params.awsBucket
        String awsKey = params.awsKey
        String fileName = params.fileName
        String pdfLink = params.pdfLink

         File file = grailsApplication.mainContext.getResource('WSCredential.properties').file
                FileInputStream fileInputStream = new FileInputStream(file)
                AmazonS3 s3Client = new AmazonS3Client(new PropertiesCredentials(fileInputStream))

                GetObjectRequest getObjectRequest = new GetObjectRequest(awsBucket, awsKey)
                userReceipt = s3Client.getObject(getObjectRequest)
          if (userReceipt)
                {
                    response.setContentType("application/image/png") 
                    response.setHeader("Content-disposition", "attachment;filename=\"${fileName}\"")
                    response.outputStream << userReceipt.getObjectContent()

                 }

Answer 1

如果你的意思是PDF的大小，那么你可以使用 头部对象.