Android 11 ACTION_OPEN_DOCUMENT_TREE: 将初始 URI 设置为文档文件夹

Question

在 Android11 中使用分区存储模型我想让用户能够选择一个文件夹，从文档文件夹开始：

val intent = Intent(Intent.ACTION_OPEN_DOCUMENT_TREE)
intent.putExtra(DocumentsContract.EXTRA_INITIAL_URI,    ???     )
startActivityForResult(intent, OPEN_DIRECTORY_REQUEST_CODE,null)

问题是，如何生成 phone 的文档文件夹的正确 URI？（它位于 root / ）在官方文档中，没有给出示例。我真的希望所有标准位置都有一些简洁的常量？

Answer 1

how can I generate a proper URI of the phone's documents folder?

测试时间：

小米M2102J20SI
模拟器 Pixel 4 XL API 30

函数askPermission()打开目标目录。

@RequiresApi(Build.VERSION_CODES.Q)
private fun askPermission() {
    val storageManager = application.getSystemService(Context.STORAGE_SERVICE) as StorageManager
    val intent =  storageManager.primaryStorageVolume.createOpenDocumentTreeIntent()

    val targetDirectory = "WhatsApp%2FMedia%2F.Statuses" // add your directory to be selected by the user
    var uri = intent.getParcelableExtra<Uri>("android.provider.extra.INITIAL_URI") as Uri
    var scheme = uri.toString()
    scheme = scheme.replace("/root/", "/document/")
    scheme += "%3A$targetDirectory"
    uri = Uri.parse(scheme)
    intent.putExtra("android.provider.extra.INITIAL_URI", uri)
    startActivityForResult(intent, REQUEST_CODE)
}

文件的 Uri 将在 onActivityResult()

中返回

 override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
        super.onActivityResult(requestCode, resultCode, data)
        if (resultCode == RESULT_OK && requestCode == REQUEST_CODE) {
            if (data != null) {
                data.data?.let { treeUri ->

                    // treeUri is the Uri of the file
                    
                   // if life long access is required the takePersistableUriPermission() is used

                    contentResolver.takePersistableUriPermission(
                            treeUri,
                            Intent.FLAG_GRANT_READ_URI_PERMISSION or
                                    Intent.FLAG_GRANT_WRITE_URI_PERMISSION
                    )

                  readSDK30(treeUri)
                }
            }
        }
    }

函数readSDK30()用于从Uri

读取文件和文件夹

  private fun readSDK30(treeUri: Uri) {
        val tree = DocumentFile.fromTreeUri(this, treeUri)!!

        thread {
            val uriList  = arrayListOf<Uri>()
            listFiles(tree).forEach { uri ->
                 
                // Collect all the Uri from here
            }
            
        }
    }

函数listFiles() returns给定Uri

中的所有文件和文件夹

fun listFiles(folder: DocumentFile): List<Uri> {
            return if (folder.isDirectory) {
                folder.listFiles().mapNotNull { file ->
                    if (file.name != null) file.uri else null
                }
            } else {
                emptyList()
            }
        }

Answer 2

我们将操纵从 StorageManager..getPrimaryStorageVolume().createOpenDocumentTreeIntent() 获得的 INITIAL_URI。

if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.Q) {
    StorageManager sm = (StorageManager) context.getSystemService(Context.STORAGE_SERVICE);

    Intent intent = sm.getPrimaryStorageVolume().createOpenDocumentTreeIntent();
    //String startDir = "Android";
    //String startDir = "Download"; // Not choosable on an Android 11 device
    //String startDir = "DCIM";
    //String startDir = "DCIM/Camera";  // replace "/", "%2F"
    //String startDir = "DCIM%2FCamera";
    String startDir = "Documents";

    Uri uri = intent.getParcelableExtra("android.provider.extra.INITIAL_URI");

    String scheme = uri.toString();

    Log.d(TAG, "INITIAL_URI scheme: " + scheme);

    scheme = scheme.replace("/root/", "/document/");

    scheme += "%3A" + startDir;

    uri = Uri.parse(scheme);

    intent.putExtra("android.provider.extra.INITIAL_URI", uri);

    Log.d(TAG, "uri: " + uri.toString());

    ((Activity) context).startActivityForResult(intent, REQUEST_ACTION_OPEN_DOCUMENT_TREE);

    return;
}

Answer 3

所有功劳都归于上述@blackapp 的！

下面是 Kotlin 语言的相同代码：

if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.Q) {
    val sm =  getSystemService(Context.STORAGE_SERVICE) as StorageManager
    intent = sm.primaryStorageVolume.createOpenDocumentTreeIntent()
    //String startDir = "Android";
    //String startDir = "Download"; // Not choosable on an Android 11 device
    //String startDir = "DCIM";
    //String startDir = "DCIM/Camera";  // replace "/", "%2F"
    //String startDir = "DCIM%2FCamera";
    val startDir = "Documents"
    var uriroot = intent.getParcelableExtra<Uri>("android.provider.extra.INITIAL_URI")    // get system root uri
    var scheme = uriroot.toString()
    Log.d("Debug", "INITIAL_URI scheme: $scheme")
    scheme = scheme.replace("/root/", "/document/")
    scheme += "%3A$startDir"                        //change uri to Documents folder
    uriroot = Uri.parse(scheme)
    intent.putExtra("android.provider.extra.INITIAL_URI", uriroot)                        // give changed uri to Intent
    Log.d("Debug", "uri: $uriroot")
  
    startActivityForResult(intent, OPEN_DIRECTORY_REQUEST_CODE);
}

正如一些评论者所提到的，此代码可能会损坏并且将来无法正常工作，这是事实。不过，考虑到Android的过去，他们无论如何都会每隔一年更换一次存储空间API。

Android 11 ACTION_OPEN_DOCUMENT_TREE: 将初始 URI 设置为文档文件夹

Android 11 ACTION_OPEN_DOCUMENT_TREE: set initial URI to the Documents folder

android

scoped-storage

android-11