使用这段代码并享受，这段代码使用 RxJava 进行网络调用：
import android.content.ContentValues
import android.content.Context
import android.os.Build
import android.os.Environment
import android.provider.MediaStore
import io.reactivex.Observable
import io.reactivex.ObservableEmitter
import okhttp3.OkHttpClient
import okhttp3.Request
import okhttp3.ResponseBody
import java.io.*
import java.net.HttpURLConnection
import java.util.concurrent.TimeUnit
class FileDownloader(
private val context: Context,
private val url: String,
private val fileName: String
) {
private val okHttpClient: OkHttpClient = OkHttpClient.Builder()
.connectTimeout(60, TimeUnit.SECONDS)
.readTimeout(60, TimeUnit.SECONDS)
.build()
private val errorMessage = "File couldn't be downloaded"
private val bufferLengthBytes: Int = 1024 * 4
fun download(): Observable<Int> {
return Observable.create<Int> { emitter ->
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) { // To Download File for Android 10 and above
val content = ContentValues().apply {
put(MediaStore.MediaColumns.DISPLAY_NAME, fileName)
put(MediaStore.MediaColumns.RELATIVE_PATH, Environment.DIRECTORY_DOWNLOADS)
}
val uri = context.contentResolver.insert(
MediaStore.Downloads.EXTERNAL_CONTENT_URI,
content
)
uri?.apply {
val responseBody = getResponseBody(url)
if (responseBody != null
) {
responseBody.byteStream().use { inputStream ->
context.contentResolver.openOutputStream(uri)?.use { fileOutStream ->
writeOutStream(
inStream = inputStream,
outStream = fileOutStream,
contentLength = responseBody.contentLength(),
emitter = emitter
)
}
emitter.onComplete()
}
} else {
emitter.onError(Throwable(errorMessage))
}
}
}
else { // For Android versions below than 10
val directory = File(
Environment.getExternalStoragePublicDirectory(
Environment.DIRECTORY_DOWNLOADS).absolutePath
).apply {
if (!exists()) {
mkdir()
}
}
val file = File(directory, fileName)
val responseBody = getResponseBody(url)
if (responseBody != null) {
responseBody.byteStream().use { inputStream ->
file.outputStream().use { fileOutStream ->
writeOutStream(
inStream = inputStream,
outStream = fileOutStream,
contentLength = responseBody.contentLength(),
emitter = emitter
)
}
emitter.onComplete()
}
} else {
emitter.onError(Throwable(errorMessage))
}
}
}
}
private fun getResponseBody(url: String): ResponseBody? {
val response = okHttpClient.newCall(Request.Builder().url(url).build()).execute()
return if (response.code >= HttpURLConnection.HTTP_OK &&
response.code < HttpURLConnection.HTTP_MULT_CHOICE &&
response.body != null
)
response.body
else
null
}
private fun writeOutStream(
inStream: InputStream,
outStream: OutputStream,
contentLength: Long,
emitter: ObservableEmitter<Int>) {
var bytesCopied = 0
val buffer = ByteArray(bufferLengthBytes)
var bytes = inStream.read(buffer)
while (bytes >= 0) {
outStream.write(buffer, 0, bytes)
bytesCopied += bytes
bytes = inStream.read(buffer)
// emitter.onNext(
((bytesCopied * 100) / contentLength).toInt()
// )
}
outStream.flush()
outStream.close()
}
}
在调用方你必须纠正这个：
private fun downloadFileFromUrl(context: Context, url: String, fileName: String) {
FileDownloader(
context = context,
url = url,
fileName = fileName
).download()
.throttleFirst(2, TimeUnit.SECONDS)
.toFlowable(BackpressureStrategy.LATEST)
.subscribeOn(Schedulers.io())
.observeOn(mainThread())
.subscribe({
// onNext: Downloading in progress
}, { error ->
// onError: Download Error
requireContext()?.apply {
Toast.makeText(this, error.message, Toast.LENGTH_SHORT).show()
}
}, {
// onComplete: Download Complete
requireContext()?.apply {
Toast.makeText(this, "File downloaded to Downloads Folder", Toast.LENGTH_SHORT).show()
}
})
}