如何在 kotlin 协程中通过 ok http 从 url 下载 pdf

Question

我想在 kotlin 中使用 ok HTTP 从 url 下载 pdf。我没有在协程中找到正确的解决方案是如何完成的。下载后我想存储在设备中并在 pdf 查看器中显示。当用户关闭 activity 时，存储文件会自动从内部存储中删除。有谁知道这是怎么做到的吗。提前致谢

class FileDownloader {

    companion object {
        private const val BUFFER_LENGTH_BYTES = 1024 * 8
        private const val HTTP_TIMEOUT = 30
    }

    private var okHttpClient: OkHttpClient

    init {
        val okHttpBuilder = okHttpClient.newBuilder()
            .connectTimeout(HTTP_TIMEOUT.toLong(), TimeUnit.SECONDS)
            .readTimeout(HTTP_TIMEOUT.toLong(), TimeUnit.SECONDS)
        this.okHttpClient = okHttpBuilder.build()
    }

    fun download(url: String, file: File): {
            val request = Request.Builder().url(url).build()
            val response = okHttpClient.newCall(request).execute()
            val body = response.body
            val responseCode = response.code
            if (responseCode >= HttpURLConnection.HTTP_OK &&
                responseCode < HttpURLConnection.HTTP_MULT_CHOICE &&
                body != null) {
                val length = body.contentLength()
                body.byteStream().apply {
                    file.outputStream().use { fileOut ->
                        var bytesCopied = 0
                        val buffer = ByteArray(BUFFER_LENGTH_BYTES)
                        var bytes = read(buffer)
                        while (bytes >= 0) {
                            fileOut.write(buffer, 0, bytes)
                            bytesCopied += bytes
                            bytes = read(buffer)
                        }
                    }
                }
            } else {
                throw IllegalArgumentException("Error occurred when do http get $url")
            }
        }
    }
}

当用户关闭 activity.

时，如何使用协程和删除文件也不起作用

Answer 1

您基本上可以将文件保存到下载文件夹中。

你要做的是；首先为您的清单文件添加读、写权限，

Android defines the following storage-related permissions: READ_EXTERNAL_STORAGE, WRITE_EXTERNAL_STORAGE, and MANAGE_EXTERNAL_STORAGE.

那么您应该为 android 高于 10 的版本使用内容解析器。例如

    val content = ContentValues().apply {
                put(MediaStore.MediaColumns.DISPLAY_NAME, fileName)
                put(MediaStore.MediaColumns.RELATIVE_PATH, Environment.DIRECTORY_DOWNLOADS)
            }
val uri = contentResolver.insert(MediaStore.Downloads.EXTERNAL_CONTENT_URI, content)
uri?.let {
      contentResolver.openOutputStream(uri)?.apply {
          BufferedOutputStream(this).write(bytes)
          }
      }

但是如果你的 android 版本低于 10 你可以使用这个例子

 val directory = File(
                    Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS).absolutePath
            ).apply {
                if (!exists()) {
                    mkdir()
                }
            }
            val file = File(directory, fileName)
            if (!file.exists()) {
                FileOutputStream(
                        File(directory, fileName)
                ).write(bytes)
            }
            uri = Uri.fromFile(file)

有关详细信息，请查看本指南https://developer.android.com/training/data-storage

如何在 kotlin 协程中通过 ok http 从 url 下载 pdf

How to download pdf from url through ok http in kotlin coroutine

android

httpurlconnection

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kotlin-coroutines