[Android] deletes existing file when trying to create new file

Author: rupinderjeet

android/src/main/kotlin/vn/hunghd/flutterdownloader/DownloadWorker.kt

@@ -148,7 +148,8 @@ class DownloadWorker(context: Context, params: WorkerParameters) :
         dbHelper = TaskDbHelper.getInstance(applicationContext)
         taskDao = TaskDao(dbHelper!!)
         val url: String =
-            inputData.getString(ARG_URL) ?: throw IllegalArgumentException("Argument '$ARG_URL' should not be null")
+            inputData.getString(ARG_URL)
+                ?: throw IllegalArgumentException("Argument '$ARG_URL' should not be null")
         val filename: String? =
             inputData.getString(ARG_FILE_NAME) // ?: throw IllegalArgumentException("Argument '$ARG_FILE_NAME' should not be null")
         val savedDir: String = inputData.getString(ARG_SAVED_DIR)
@@ -170,9 +171,9 @@ class DownloadWorker(context: Context, params: WorkerParameters) :
         val task = taskDao?.loadTask(id.toString())
         log(
             "DownloadWorker{url=$url,filename=$filename,savedDir=$savedDir,header=$headers,isResume=$isResume,status=" + (
-                task?.status
-                    ?: "GONE"
-                )
+                    task?.status
+                        ?: "GONE"
+                    )
         )
 
         // Task has been deleted or cancelled
@@ -209,7 +210,14 @@ class DownloadWorker(context: Context, params: WorkerParameters) :
             taskDao = null
             Result.success()
         } catch (e: Exception) {
-            updateNotification(applicationContext, filename ?: url, DownloadStatus.FAILED, -1, null, true)
+            updateNotification(
+                applicationContext,
+                filename ?: url,
+                DownloadStatus.FAILED,
+                -1,
+                null,
+                true
+            )
             taskDao?.updateTask(id.toString(), DownloadStatus.FAILED, lastProgress)
             e.printStackTrace()
             dbHelper = null
@@ -306,14 +314,16 @@ class DownloadWorker(context: Context, params: WorkerParameters) :
                 log("Open connection to $url")
                 httpConn.connectTimeout = actualTimeout
                 httpConn.readTimeout = actualTimeout
-                httpConn.instanceFollowRedirects = false // Make the logic below easier to detect redirections
+                httpConn.instanceFollowRedirects =
+                    false // Make the logic below easier to detect redirections
                 httpConn.setRequestProperty("User-Agent", "Mozilla/5.0...")
 
                 // setup request headers if it is set
                 setupHeaders(httpConn, headers)
                 // try to continue downloading a file from its partial downloaded data.
                 if (isResume) {
-                    downloadedBytes = setupPartialDownloadedDataHeader(httpConn, actualFilename, savedDir)
+                    downloadedBytes =
+                        setupPartialDownloadedDataHeader(httpConn, actualFilename, savedDir)
                 }
                 responseCode = httpConn.responseCode
                 when (responseCode) {
@@ -469,7 +479,14 @@ class DownloadWorker(context: Context, params: WorkerParameters) :
             }
         } catch (e: IOException) {
             taskDao!!.updateTask(id.toString(), DownloadStatus.FAILED, lastProgress)
-            updateNotification(context, actualFilename ?: fileURL, DownloadStatus.FAILED, -1, null, true)
+            updateNotification(
+                context,
+                actualFilename ?: fileURL,
+                DownloadStatus.FAILED,
+                -1,
+                null,
+                true
+            )
             e.printStackTrace()
         } finally {
             if (outputStream != null) {
@@ -497,17 +514,33 @@ class DownloadWorker(context: Context, params: WorkerParameters) :
     private fun createFileInAppSpecificDir(filename: String, savedDir: String): File? {
         val newFile = File(savedDir, filename)
         try {
-            val rs: Boolean = newFile.createNewFile()
-            if (rs) {
-                return newFile
-            } else {
-                logError("It looks like you are trying to save file in public storage but not setting 'saveInPublicStorage' to 'true'")
+            if (newFile.exists()) {
+                val deleted = newFile.delete()
+                if (!deleted) {
+                    logError("Unable to delete existing file: ${newFile.absolutePath}")
+                    return null
+                }
             }
+
+            val created: Boolean = newFile.createNewFile()
+            if (!created) {
+                logError(
+                    """
+                        Unable to create new file: ${newFile.absolutePath}.
+                         Are are trying to save file in public storage 
+                         but not setting 'saveInPublicStorage' to 'true'?
+                    """.trimIndent()
+                )
+                return null
+            }
+
+            return newFile
+
         } catch (e: IOException) {
             e.printStackTrace()
             logError("Create a file using java.io API failed ")
+            return null
         }
-        return null
     }
 
     /**
@@ -602,15 +635,18 @@ class DownloadWorker(context: Context, params: WorkerParameters) :
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
             // Create the NotificationChannel
             val res = applicationContext.resources
-            val channelName: String = res.getString(R.string.flutter_downloader_notification_channel_name)
-            val channelDescription: String = res.getString(R.string.flutter_downloader_notification_channel_description)
+            val channelName: String =
+                res.getString(R.string.flutter_downloader_notification_channel_name)
+            val channelDescription: String =
+                res.getString(R.string.flutter_downloader_notification_channel_description)
             val importance: Int = NotificationManager.IMPORTANCE_LOW
             val channel = NotificationChannel(CHANNEL_ID, channelName, importance)
             channel.description = channelDescription
             channel.setSound(null, null)
 
             // Add the channel
-            val notificationManager: NotificationManagerCompat = NotificationManagerCompat.from(context)
+            val notificationManager: NotificationManagerCompat =
+                NotificationManagerCompat.from(context)
             notificationManager.createNotificationChannel(channel)
         }
     }
@@ -769,7 +805,9 @@ class DownloadWorker(context: Context, params: WorkerParameters) :
 
     private fun isImageOrVideoFile(contentType: String): Boolean {
         val newContentType = getContentTypeWithoutCharset(contentType)
-        return newContentType != null && (newContentType.startsWith("image/") || newContentType.startsWith("video"))
+        return newContentType != null && (newContentType.startsWith("image/") || newContentType.startsWith(
+            "video"
+        ))
     }
 
     private fun isExternalStoragePath(filePath: String?): Boolean {