使用cordova和文件插件强制Android上的外部SD卡

Question

In a cordova android app (scroll to the bottom for device,version, plugin list, all of it quite up-to-date as of this writing) I want to preferentially store file on the external SDCard and use internal storage if SDCard not there. I am setting my save path to:

persistentFS= cordova.file.externalDataDirectory||cordova.file.DataDirectory||fileSystem.root.toURL();

Its eventual value is file:///storage/emulated/0/Android/data/com.fubar.app/files/, same as cordova.file.externalDataDirectory.

I have set: <access origin="cdvfile://*" /> ... <preference name="AndroidPersistentFileLocation" value="Compatibility" /> <preference name="AndroidExtraFilesystems" value="files-external,sdcard,files,documents,cache,cache-external,root" /> in config.xml, <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

in AndroidManifest.xml and set various enchantments in index.html Security metatag. I add that a SDcard is inserted, write-enabled and I confirm that I can write to it with - for example - a file manger. It contains the Android/data/com.fubar.myapp/files/ folder, as it should.

All for nothing: files get written to - and read from - the internal device storage. I have read all google scavenged on this topic but nothing has brought me closer to the task (some folks suggest using the file-system-roots plugin, but it appears to have been subsumed by the file plugin).

Any hints? TIA, alf

Edit: Using adb shell, I can see that the external sdcard files folder for the app has an absolute path of:

`/storage/extSdCard/Android/data/com.fubar.myapp/files`

and calling resolveLocalFileSystemURL on

file:///storage/extSdCard/Android/data/com.fubar.myapp/files

happily succeeds. I do not think that is the way to go, as that path is device dependent.

---

Device: Samsung Galaxy tab 10.5, lollipop 5.0.1 using cordova 5.3.1, with plugins: cordova-plugin-device 1.0.1 "Device" cordova-plugin-dialogs 1.1.1 "Notification" cordova-plugin-file 3.0.0 "File" cordova-plugin-file-transfer 1.3.0 "File Transfer" cordova-plugin-media 1.0.1 "Media" cordova-plugin-whitelist 1.1.0 "Whitelist"

Build host is Linux FC21

Answer 1

You can call Context.getExternalFilesDirs() . That returns an array of directories to which your app can write data. One of which will be the sdcard path /storage/sdcardname/Android/data/appname/files.

Most manufacturers also set the SECONDARY_STORAGE environment variable to expose the SD Card root path. You can try calling System.getenv("SECONDARY_STORAGE")

Android does not expose any API that allows you to get the path of the sdcard root path. You can use reflection and obtain the sdcard root path from StorageManager.java -> getVolumePaths() - http://androidxref.com/5.1.1_r6/xref/frameworks/base/core/java/android/os/storage/StorageManager.java#590

Answer 2

Since there doesn't seem to be a true Cordova answer to this yet here is what I found using the file plugin . I was also looking to save on the SD card as well as the data will later be attached to email and Gmail now requires an attachment to be loaded from SD. This blog got me going in the right direction https://www.neontribe.co.uk/cordova-file-plugin-examples/ . In the section talking about writing a file basically just replace

window.resolveLocalFileSystemURL(cordova.file.dataDirectory, function (directoryEntry) {

with this

window.resolveLocalFileSystemURL(cordova.file.externalDataDirectory, function (directoryEntry) {

And it should be working.