从安卓/模拟/0/下载获取文件列表

Question

您好，我正在编写应用程序，其中一个功能是读取下载的数据，我想获取android/emulated/0/Download包含的所有文件。我知道它是一个内部存储，我在清单文件中只有外部存储的权限，我不知道如何添加从此目录读取数据的权限。

 ArrayList<String> files = findURs(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS), new ArrayList<String>());

这段代码是由另一个用户编写的，但我只编辑了它

public ArrayList<String> findURs(File dir, ArrayList<String> matchingURFileNames) {
    String safPattern = ".ur";
    File listFile[] = dir.listFiles();
    if (listFile != null) {
        for (int i = 0; i < listFile.length; i++) {
            if (listFile[i].isDirectory()) {
                findURs(listFile[i], matchingURFileNames);
            } else {
                if (listFile[i].getName().endsWith(safPattern)) {
                    matchingURFileNames.add(dir.toString() + File.separator + listFile[i].getName());
                }
            }
        }
    }
    return matchingURFileNames;
}

Answer 1

首先像这样做一个运行时性能检查，

private int REQUEST_CODE = 100;
private static String[] PERMISSIONS = {Manifest.permission.WRITE_EXTERNAL_STORAGE};
 private void checkPermissions() {
        if (ActivityCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE) ==
                PackageManager.PERMISSION_DENIED) {
            ActivityCompat.requestPermissions(this, PERMISSIONS, REQUEST_CODE);

    } else {
       ArrayList<String> files = findURs(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS), new ArrayList<String>());
    }

}

处理您的权限结果，

@Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        if (requestCode == REQUEST_CODE) {
            if (grantResults.length > 0
                    && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
           ArrayList<String> files = findURs(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS), new ArrayList<String>());
            }
        }
    }

还要添加清单，

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />