如何在Cassandra中存储和检索base64编码的图像 [英] How to store and retrieve base64 encoded image in Cassandra

问题描述

我正在通过 json 消息以 base64 格式发送图像

I am sending an image in base64 format in a json message

image:["data:image/png; base64，iVBORw ..."，"data:image/png; base64，idfsd ..."]

我想将此图像存储在 Cassandra 中.此 json 作为 Array [String] -

I want to store this image in Cassandra. This json maps to my model as an Array[String] -

case class ImageArray(
image: Array[String]
}

我已经读过要在cassandra中存储图像，我需要ByteBuffer.因此，我使用ByteBuffer.wrap()将数组的数组不同索引转换为ByteBuffer.

I have read that to store images in cassandra, I need ByteBuffer. So I use ByteBuffer.wrap() to convert the array different indexes of the array into ByteBuffer.

ByteBuffer.wrap(model.image(0).getBytes()) //for the moment, I am taking only 1 image

我无法弄清楚如何将 ByteBuffer 转换回 String .我可以从 Cassandra 中检索字节，如下所示

I am unable to figure out how to conovert the ByteBuffer back into a String. I can retrieve the bytes from Cassandra like follows

(row.getBytes("image"))

以上内容为我提供了一个 ByteBuffer .如何将其转换为 String ，以后可以用来创建 Array [String]

The above gives me a ByteBuffer. How do I convert this into a String which I could use later to create an Array[String]

推荐答案

尽管我能够解决它，但是该方法非常缓慢，因此我放弃了将图像存储为字节并将其保存为字符串(base64)的想法.这就是我从服务器上得到的.

Though I was able to solve it, the method was very slow so I dropped the idea of storing images as bytes and kept them as string (base64) as that is what I am getting from the server.

出于原始问题，为了解决该问题，我进行了一些更改.

Coming to the original issue, to solve the problem, I made a few changes.

随着Cassandra了解列表，将数组中的数组更改为列表

Changed Array to List in the model as Cassandra understand Lists

case class ImageArray(
image: List[String]
}

通过创建自定义的 Reads -(JsPath \"image").read [List [String]]

在 cassandra 中，用于存储图像数组的表模式为 image list< blob>，

In cassandra, the table schema for storing the image arrays was image list<blob>,

一旦在模型中有了列表，我便将其转换为 String 的 List 到 Byte List >使用 .value("image"，seqAsJavaList((((ByteBuffer.wrap(model.image(0).getBytes())).array().toList):::((ByteBuffer.wrap(model.image(1).getBytes())).array().toList)))

Once I had the List in the model, I converted it into List of String into List of Byte using .value("image",seqAsJavaList(((ByteBuffer.wrap(model.image(0).getBytes())).array().toList):::((ByteBuffer.wrap(model.image(1).getBytes())).array().toList)))

上面，我获取了图像列表的第一个元素(一个字符串，它是索引0处图像的base64表示形式)，使用 ByteBuffer.wrap 将其转换为字节，然后转换为 ByteBuffer 转换为 Array ，然后将其转换为 List .这给了我 List [Byte] 作为第一张图片.我对image(1)重复此操作，然后使用 ::: 将两个图像合并.然后，我使用 seqAsJavaList 将此 Scala List 转换为 Java .

Above, I took the first element of image list (a string which is base64 representation of image at index 0), convert it into byte using ByteBuffer.wrap, then converted ByteBuffer to Array and then converted it to List. This gave me List[Byte] for 1st image. I repeat it for image(1) and then join the two images using :::. Then I convert this Scala List to Java using seqAsJavaList.

注意:由于上述方法需要多次转换，因此这不是最佳方法.相反，我决定将图像存储为List [String]

Note: As the above method required multiple conversions, it isn't a optimal way. I instead decided to store the image as List[String]

这篇关于如何在Cassandra中存储和检索base64编码的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！