带有React Native的ClojureScript-文件下载

Question

我想用ClojureScript从移动应用程序下载一个文件到手机存储中，并使用本地react。文件已经上传到AmazonS3存储桶中。文件URL类似于https://s3.amazonaws.com/client-texastech/uploads/art_pictures-images/comma-2005-06/96acad35-7f3f-4b10-a104-5bf59b92b463/medium/image.jpg?X-Amz算法＝AWS4-HMAC-SHA256&X-Amz-Credential=AKIAIQETNIOQ45P7UIKQ%2F20181113%2Fus-east-1%2Fs3%2Faws4_request&X-Amz日期=20181113T023654Z&X-Amz-Expires=300&X-Amz-SignedHeaders=主机&X-Amz签名=576787721283e1c2b0d8fd2349cd304b5f7f717491edd3d8d7ba256ef52f6a8

我发现了react native fetch blob。

我试着用它：

(def RNFetchBlob (js/require "react-native-fetch-blob"))
(def fetch-blob (oget RNFetchBlob "default"))
(def fs (oget RNFetchBlob "fs"))
(defn download-url [app-db url]
(p/promise (fn [resolve reject]
(let [fs (oget fetch-blob "fs")
dir-path (str (oget (oget fs "dirs") "DocumentDir") "/image.png")
fetch-config (ocall fetch-blob "config" {
:addAndroidDownloads {:useDownloadManager true :path dir-path :notification true}
:Cache-Control "no-store"}) 
fetch-file (ocall fetch-config "fetch" "GET" url (util/get-token app-db))
base64 (oget fetch-blob "base64")]
(ocall fetch-file "then" (fn [res]
(.log js/console "Download file completed." res)
(resolve true)))
(ocall fetch-file "catch" (fn [res]
(.log js/console "Download file failed" res)
(resolve false)))
#js{:timeout 600000
:distanceFilter 1
:maximumAge 1000
:enableHighAccuracy false}))))

下载已完成。但是，我在任何文件夹中都找不到该文件。有什么问题吗？如果是，有人能分享代码片段吗？

Answer 1

如果您想下载并显示S3中的任何图像，您可以使用具有源属性的RN图像

[image {:source "https://your.s3.bucket/path.jpg"}]

如果它只是一个文件，那么使用rn提取blob

(defn fetch-file! [url]
(let [result (promise-chan)]
(-> RNFetchBlob
(.config #js{})
(.fetch "GET" url)
(.then #(.text %))
(.then #(put! result [true %]))
(.catch #(put! result [false %])))
result))

确保您可以访问S3文件

Answer 2

最后，我能够下载该文件。问题是我将参数传递到配置调用的位置。我们应该使用clj->JS将Clojure转换为JS。更新后的方法如下：

(defn download-image-android [app-db url image-id]
(p/promise (fn [resolve reject]
(let [fs (oget fetch-blob "fs")
android-dir-path (str (oget (oget fs "dirs") "DownloadDir") "/" image-id ".jpg")
params (parse-params url)
fetch-config (ocall fetch-blob "config" (clj->js {
:fileCache true
:addAndroidDownloads {:useDownloadManager true :path android-dir-path :notification true}})) 
fetch-file (ocall fetch-config "fetch" "GET" url (clj->js {:Signature (:X-Amz-Signature params)
:Cache-Control "no-store"}))]
(ocall fetch-file "then" (fn [res]
(show-alert "Success" "Image has been saved to the phone successfully!")
(resolve true)))
(ocall fetch-file "catch" (fn [res]
(show-alert "Error" "Image cannot be downloaded. Please try again!")
(.log js/console "Download file failed" res)
(resolve false)))
#js{:timeout 30000
:distanceFilter 1
:maximumAge 1000
:enableHighAccuracy false}))))