// 如果當前目錄下沒有 fileDirName 文件夾會自動創(chuàng)建
val file:File = context.getExternalFileDir("fileDirName") // fileDirName 文件夾名稱
// /storage/emulated/0/Android/data/packageName/files/fileDirName

  val appFileDirName = applicationContext.getExternalFilesDir("fileDirName")?.absolutePath
  val newFile = File(appFileDirName, "temp.txt")
  val fileWriter = FileWriter(newFile)
  fileWriter.write("test information")
  fileWriter.flush()
  fileWriter.close()

    /**
     * @param fileName 文件名稱
     * @param relativePath 包含某個媒體下的子路徑
     */
    fun insertFileIntroMediaStore(
        context: Context,
        fileName: String,
        relativePath: String
    ): Uri? {
        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.Q) {
            return null
        }
        val contentResolver = context.contentResolver
        val values = ContentValues()
        values.put(MediaStore.Downloads.DISPLAY_NAME, fileName)
        values.put(MediaStore.Downloads.MIME_TYPE, "text/plain")
        values.put(MediaStore.Downloads.RELATIVE_PATH, relativePath)
      	//驗證存儲空間的可用性 
      	//由于外部存儲空間位于用戶可能能夠移除的物理卷上，因此在嘗試從外部存儲空間讀取應用專
      	//屬數(shù)據(jù)或?qū)脤贁?shù)據(jù)寫入外部存儲空間之前，請驗證該卷是否可訪問。
      	//您可以通過調(diào)用 Environment.getExternalStorageState() 查詢該卷的狀態(tài)。如果返回的狀態(tài)為 MEDIA_MOUNTED，那么您就可以在外部存儲空間中讀取和寫入應用專屬文件。如果返回的狀態(tài)為 MEDIA_MOUNTED_READ_ONLY，您只能讀取這些文件。
        val externalStorageState = Environment.getExternalStorageState()
        return if (externalStorageState.equals(Environment.MEDIA_MOUNTED)) {
            contentResolver.insert(MediaStore.Downloads.EXTERNAL_CONTENT_URI, values)
        } else {
            contentResolver.insert(MediaStore.Downloads.INTERNAL_CONTENT_URI, values)
        }
    }

    /**
     * @param context 上下文
     * @param insertUri 存儲Uri
     * @param inputStream 文件輸出流
     */
    fun saveFile(context: Context, insertUri: Uri?, inputStream: InputStream?) {
        insertUri ?: return
        inputStream ?: return
        val resolver = context.contentResolver
        val out = resolver.openOutputStream(insertUri)
        var read: Int
        val buffer = ByteArray(1024)
        while (inputStream.read(buffer).also { read = it } != -1) {
            out?.write(buffer)
        }
        inputStream.close()
        out?.flush()
        out?.close()
    }

    /**
     * @param context 上下文
     * @param insertUri 存儲Uri
     * @param sourceFile 資源文件
     */
    fun saveFile(context: Context, insertUri: Uri?, sourceFile: File?) {
        insertUri ?: return
        sourceFile ?: return
        val inputStream = FileInputStream(sourceFile)
        val resolver = context.contentResolver
        val out = resolver.openOutputStream(insertUri)
        var read: Int
        val buffer = ByteArray(1024)
        while (inputStream.read(buffer).also { read = it } != -1) {
            out?.write(buffer)
        }
        inputStream.close()
        out?.flush()
        out?.close()
    }

    /**
     * 獲取文件輸出流 by uri
     * @param context 上下文
     * @param uri 文件路徑
     */
    fun getInputStreamByUri(context: Context, uri: Uri?): InputStream? {
        uri ?: return null
        val openFileDescriptor = context.contentResolver.openFileDescriptor(uri, "r")
        return FileInputStream(openFileDescriptor?.fileDescriptor)
    }