如何使用Google App Engine Blobstore压缩图像 [英] How to compress images with Google App Engine Blobstore

问题描述

我们有一个应用程序，用于从blobstore服务一系列图像。一个
的例子就在这里：

http ：//lh4.ggpht.com/f76xUkRZLRkb_Qz5uu82TX3LoBRh4eYb9hxYwMRMLCk5ghO_OL0DW2v4rRnkewUyDWfBuBttgbUvuJJXwtFQosEB=s0

这是一个庞大的png，所以这个下载量为536K。

如果我们把它调整到400，它仍然很大（263k）： b
$ b

http://lh4.ggpht.com/f76xUkRZLRkb_Qz5uu82TX3LoBRh4eYb9hxYwMRMLCk5ghO_OL0DW2v4rRnkewUyDWfBuBttgbUvuJJXwtFQosEB=s400

我们如何可以请求或存储图片的某种更好的
压缩？我们有一个移动客户端用于我们的应用程序，并且通过
等待273K使它真的很慢。

图片API 。压缩和调整图像大小：

  //从blobstore获取图像
 ImagesService imagesService = ImagesServiceFactory.getImagesService（）; 
 Image oldImage = ImagesServiceFactory.makeImageFromBlob（blobKey）; 
 
 // compress&调整大小
 OutputSettings settings = new OutputSettings（ImagesService.OutputEncoding.JPEG）; 
 settings.setQuality（90）; 
 Transform transform = ImagesServiceFactory.makeResize（newWidth，newHeight）
图片newImage = imagesService.applyTransform（transform，oldImage，settings）; 
 byte [] blobData = newImage.getImageData（）; 
 
 //将数据保存到blobstore 
 FileService fileService = FileServiceFactory.getFileService（）; 
 AppEngineFile file = fileService.createNewBlobFile（image / jpeg，someFilename）; 
 FileWriteChannel writeChannel = fileService.openWriteChannel（file，true）; 
 writeChannel.write（ByteBuffer.wrap（blobData））; 
 writeChannel.closeFinally（）; 
 
 //将blobKey写入新写入的数据
 BlobKey blobKey = fileService.getBlobKey（file）; 
  

We have an app that servers a series of images from blobstore. An example is here:

http://lh4.ggpht.com/f76xUkRZLRkb_Qz5uu82TX3LoBRh4eYb9hxYwMRMLCk5ghO_OL0DW2v4rRnkewUyDWfBuBttgbUvuJJXwtFQosEB=s0

It was a huge png, so this downloads at 536K.

If we resize it to 400 across, it's still huge (263k):

http://lh4.ggpht.com/f76xUkRZLRkb_Qz5uu82TX3LoBRh4eYb9hxYwMRMLCk5ghO_OL0DW2v4rRnkewUyDWfBuBttgbUvuJJXwtFQosEB=s400

How can we request or store the picture in some kind of better compression? We have a mobile client for our app, and waiting through 273K is making it really slow.

解决方案

There is Images API. To compress and resize image:

// get image from blobstore
ImagesService imagesService = ImagesServiceFactory.getImagesService();
Image oldImage = ImagesServiceFactory.makeImageFromBlob(blobKey); 

// compress & resize it
OutputSettings settings = new OutputSettings(ImagesService.OutputEncoding.JPEG);
settings.setQuality(90);
Transform transform = ImagesServiceFactory.makeResize(newWidth, newHeight) 
Image newImage = imagesService.applyTransform(transform, oldImage, settings);
byte[] blobData = newImage.getImageData();

//save data to blobstore
FileService fileService = FileServiceFactory.getFileService();
AppEngineFile file = fileService.createNewBlobFile("image/jpeg", someFilename);
FileWriteChannel writeChannel = fileService.openWriteChannel(file, true);
writeChannel.write(ByteBuffer.wrap(blobData));
writeChannel.closeFinally();

// get the blobKey to newly written data
BlobKey blobKey = fileService.getBlobKey(file);

这篇关于如何使用Google App Engine Blobstore压缩图像的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！