意图ACTION_OPEN_DOCUMENT_TREE似乎没有返回行驶的真实路径

问题描述

我正在尝试从连接到Google Pixel的USB存储设备读取文件.我目前正在使用此方法选择驱动器的路径，以便可以查询驱动器的内容

I'm trying to read files from a USB storage device connected to my Google Pixel. I'm currently using this method to select the path of the drive so I can query it for its contents

private static final String TAG = "MainActivity";
private static final int REQUEST_CHOOSE_DRIVE = 1;
private TextView tv;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    tv = (TextView) findViewById(R.id.text);

    Intent i = new Intent(Intent.ACTION_OPEN_DOCUMENT_TREE);

    startActivityForResult(i, REQUEST_CHOOSE_DRIVE);
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    if (requestCode == REQUEST_CHOOSE_DRIVE) {

        Uri uri = data.getData();

    }
}

但是，Uri看起来像/tree/...，在Android文件系统中似乎不是真实路径(通过adb shell验证).如何使用此uri查询便携式存储设备的内容?我尝试使用给出的答案，但链接的函数返回null.

However, the Uri looks something like /tree/... which doesn't seem to be a real path in the Android file system (verified via adb shell). How can I use this uri to query the contents of a portable storage device? I tried using the answer given here but the linked function returns null.

推荐答案

您正在获取树Uri.因此，您需要添加以下代码才能从Tree Uri获取文件.

You are getting tree Uri. So you need to Add below code to get files from Tree Uri.

        DocumentFile documentFile = DocumentFile.fromTreeUri(this, uri);
        for (DocumentFile file : documentFile.listFiles()) {

            if(file.isDirectory()){ // if it is sub directory
                // Do stuff with sub directory
            }else{
                // Do stuff with normal file
            }

           Log.d("Uri->",file.getUri() + "\n");

        }

要查询内容，可以使用以下代码.

For the query the contents, you can use below code.

ContentResolver contentResolver = getActivity().getContentResolver();
    Uri docUri = DocumentsContract.buildDocumentUriUsingTree(uri,
            DocumentsContract.getTreeDocumentId(uri));
    Uri childrenUri = DocumentsContract.buildChildDocumentsUriUsingTree(uri,
            DocumentsContract.getTreeDocumentId(uri));
Cursor docCursor = contentResolver.query(docUri, new String[]{
            Document.COLUMN_DISPLAY_NAME, Document.COLUMN_MIME_TYPE}, null, null, null);
    try {
        while (docCursor.moveToNext()) {
            Log.d(TAG, "found doc =" + docCursor.getString(0) + ", mime=" + docCursor
                    .getString(1));

        }
    } finally {
        // close cursor
    }

您可以检查Google示例代码: https://github.com/googlesamples/android-DirectorySelection/blob/master/Application/src/main/java/com/example/android/directoryselection/DirectorySelectionFragment.java#L150

You can check Google sample code:https://github.com/googlesamples/android-DirectorySelection/blob/master/Application/src/main/java/com/example/android/directoryselection/DirectorySelectionFragment.java#L150

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