如何在 Clojure 中将整个二进制文件(Nippy)读入字节数组?

问题描述

我需要将存储在磁盘上的 Nippy 数据结构转换为 Nippy 可以读取的数据吗?Nippy 使用字节数组，因此我需要某种方法将文件转换为字节数组.我试过了

I need to convert Nippy data structures stored on disk into something that can be read by Nippy? Nippy uses byte arrays, so I need some way to convert the file into a byte array. I have tried

(clojure.java.io/to-byte-array (clojure.java.io/file folder-path file-path))

但这给了

java.lang.IllegalArgumentException: Value out of range for byte: ?

然后我尝试:

(into-array Byte/TYPE  (map byte (slurp (clojure.java.io/file folder-path file-path))))

但不知何故命名空间是错误的，我找不到正确的.

but somehow the namespace is wrong, and I can't find the right one.

首先要编写 Nippy 结构，我使用:

To write the Nippy structures in the first place, I am using:

(with-open [w (clojure.java.io/output-stream file-path)]
    (.write w (nippy/freeze data)))))

推荐答案

我不知道 Clojure 有什么内置的可以处理这个问题.您绝对不想要 slurp 因为这会将流内容解码为文本.

I'm not aware of anything built-in to Clojure that will handle this. You definitely don't want slurp because that will decode the stream contents as text.

您可以编写自己的方法来执行此操作，基本上是从 InputStream 读取到缓冲区并将缓冲区写入 java.io.ByteArrayOutputStream.或者你可以使用 IOUtils来自 Apache Commons IO 的 类:

You could write your own method to do this, basically reading from the InputStream into a buffer and writing the buffer to a java.io.ByteArrayOutputStream. Or you could use the IOUtils class from Apache Commons IO:

 (require '[clojure.java.io :as io])
 (import '[org.apache.commons.io IOUtils])

 (IOUtils/toByteArray (io/input-stream file-path))

您还应该看看 Nippy 的 thaw-from-in! 和 freeze-to-out! 函数:

You should also take a look at Nippy's thaw-from-in! and freeze-to-out! functions:

 (import '[java.io DataInputStream DataOutputStream])

 (with-open [w (io/output-stream file-path)]
   (nippy/freeze-to-out! (DataOutputStream. w) some-data))

 (with-open [r (io/input-stream file-path)]
   (nippy/thaw-from-in! (DataInputStream. r)))

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