Golang how can I integrate new package into my image upload code

huangapple
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英文:

Golang how can I integrate new package into my image upload code

问题

我是新手使用Golang，我有一个函数可以将图像上传到我的Amazon S3账户并保存。一切都很顺利，但是我想找到一种方法来调整图像的大小，因为有些图像大小高达4MB。我找到了一个可以正确调整图像大小的包https://github.com/disintegration/imaging。我的问题是，我如何使用新调整大小的图像而不是旧文件进行上传？例如，这是我的原始代码，用于上传图像而不调整大小：

  1. func UploadProfile(w http.ResponseWriter, r *http.Request) {
  2.     r.ParseForm()
  3.     var buff bytes.Buffer
  4.     var result string
  6.     sess, _ := "access keys"
  8.     svc := s3.New(sess)
  10.     file, handler, err := r.FormFile("file")
  11.     if err != nil {
  12.         fmt.Println("Error Uploading Image")
  13.         return
  14.     }
  15.     defer file.Close()
  16.     read_file,err := ioutil.ReadAll(file)
  17.     fileBytes := bytes.NewReader(read_file)
  18.     if err != nil {
  19.         fmt.Println("Error Reading file")
  20.         return
  21.     }
  24.     file.Read(read_file)
  25.     path := handler.Filename
  26.     params := &s3.PutObjectInput{
  27.         Bucket: aws.String("amazon-bucket"),
  28.         Key: aws.String(path),
  29.         Body: fileBytes,
  30.     }
  31.     resp, err := svc.PutObject(params)
  32.     if err != nil {
  33.         fmt.Printf("bad response: %s", err)
  35.     }
  37. }

我现在遇到的问题是下面的代码片段：

  1. file_open,err := imaging.Open("myImage.jpg")
  3. if err != nil {
  4.     print("Imaging Open error")
  5. }
  6. new_image := imaging.Resize(file_open, 300, 300, imaging.Lanczos)
  7. errs := imaging.Save(new_image, "dst.jpg")
  8. if errs != nil {
  9.     print(err)
  10. }

上面的代码获取任何图像并将其调整为300x300，这正是我想要的，现在我如何使用这个新图像并将其发送到我的S3图像存储桶？让我困惑的部分是，new_image的类型是image.NRGBA，而原始图像的类型是Multipart.File。当我将图像上传到Amazon时，它想要知道图像有多少字节，我不能像下面这样做：

  1. read_file,err := ioutil.ReadAll(new_image)
  2. if err != nil {
  3.     fmt.Println("Error Reading file")
  4.     return
  5. }

因为它只接受io.Reader类型的参数，有没有解决这个问题的方法？这样我就可以将新图像保存到Amazon S3了。

英文:

I am new to Golang and have a function that uploads an image to my Amazon s3 account and saves it . Everything works great however I was looking for a way to resize images as some images are up to 4MB in size. I found a package that works correctly for resizing images https://github.com/disintegration/imaging . My question is how can I use the new resized image instead of the old file to upload ? For instance this is my original code that uploads an image and does not resize

  1. func UploadProfile(w http.ResponseWriter, r *http.Request) {
  2. 	 r.ParseForm()
  3. 	 var buff bytes.Buffer
  4.          var result string
  6. 	
  7. 	 sess, _ := "access keys"
  9. 	 svc := s3.New(sess)
  11. 	 file, handler, err := r.FormFile("file")
  12. 	 if err != nil {
  13. 		 fmt.Println("Error Uploading Image")
  14. 		 return
  15. 	 }
  16. 	 defer file.Close()
  17. 	 read_file,err := ioutil.ReadAll(file)
  18.      fileBytes := bytes.NewReader(read_file)
  19. 	 if err != nil {
  20. 		 fmt.Println("Error Reading file")
  21. 		 return
  22. 	 }
  25. 	 file.Read(read_file)
  26. 	 path := handler.Filename
  27. 	 params := &s3.PutObjectInput{
  28. 		 Bucket: aws.String("amazon-bucket"),
  29. 		 Key: aws.String(path),
  30.          Body: fileBytes,
  31. 	 }
  32. 	 resp, err := svc.PutObject(params)
  33. 	 if err != nil {
  34. 		 fmt.Printf("bad response: %s", err)
  35. 	
  36. 	 }
  38.  }

The issue I am now having is with this snippet below

  1.  file_open,err := imaging.Open("myImage.jpg")
  3. 		if err != nil {
  4. 			print("Imaging Open error")
  5. 		}
  6. 		new_image := imaging.Resize(file_open, 300, 300, imaging.Lanczos)
  7. 		errs := imaging.Save(new_image, "dst.jpg")
  8. 		if errs != nil {
  9. 			print(err)
  10. 		}

The code above gets any image and resizes it to 300 by 300 which is exactly what I want, now how can I use that new Image and send it to my s3 image bucket ? The part that confuses me is that the new_image is of type image.NRGBA while the original image is of type Multipart.File . When I upload an image to Amazon it wants to know how many bytes it has and I can't do something like

  1. read_file,err := ioutil.ReadAll(new_image)
  2. 		if err != nil {
  3. 			fmt.Println("Error Reading file")
  4. 			return
  5. 		}

because it only expects something of type io.Reader is there any work around this ? so that I can save my new Image to Amazon s3 ?

答案1

得分: 2

你正在将新图像保存到文件中，然后没有对该文件进行任何操作。如果你想要的话，可以从磁盘中读取该文件，或者可以在内存中对其进行编码：

  1. ...
  2. resized := imaging.Resize(fileOpen, 300, 300, imaging.Lanczos)
  4. var buf bytes.Buffer
  5. err = imaging.Encode(&buf, resized, imaging.JPEG)
  6. if err != nil {
  7.     log.Println(err)
  8.     return
  9. }
  11. params := &s3.PutObjectInput{
  12.     Bucket: aws.String("amazon-bucket"),
  13.     Key:    aws.String(path),
  14.     Body:   buf.Bytes(),
  15. }
  16. ...
英文:

You're saving the new image to a file, then not doing anything with that file. You could read the file off the disk if you want, or you could encode it in memory:

  1. ...
  2. resized := imaging.Resize(fileOpen, 300, 300, imaging.Lanczos)
  4. var buf byte.Buffer
  5. err = imaging.Encode(&buf, resized, imaging.JPEG)
  6. if err != nil {
  7. 	log.Println(err)
  8. 	return
  9. }
  11. params := &s3.PutObjectInput{
  12. 	Bucket: aws.String("amazon-bucket"),
  13. 	Key:    aws.String(path),
  14. 	Body:   buf.Bytes(),
  15. }
  16. ...

huangapple
  • 本文由 发表于 2017年1月14日 06:57:30
  • 转载请务必保留本文链接：https://go.coder-hub.com/41644747.html
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