http - 如何在 Common Lisp/dexador 中从 http 地址下载并保存图像？

Question

在 Common Lisp 中，您如何从网站下载图像并将其保存到包文件夹中？我很难在 dexador 的文档中查找此类功能。

提前致谢

Answer 1

你得到一个字节向量，所以只保存它:

(let ((bytes (dex:get uri)))
  (with-open-file (out filename
                       :direction :output
                       :if-exists :supersede
                       :if-does-not-exist :create
                       :element-type 'unsigned-byte)
    (write-sequence bytes out)))

如果数据太多，您可能需要使用缓冲流副本:

(let ((byte-stream (dex:get uri :want-stream t))
      (buffer (make-array buffer-size :element-type 'unsigned-byte)))
  (with-open-file (out filename
                       :direction :output
                       :if-exists :supersede
                       :if-does-not-exist :create
                       :element-type 'unsigned-byte)
    (loop :for p := (read-sequence buffer byte-stream)
          :while (plusp p)
          :do (write-sequence buffer out :end p))))