从外部存储读取数据库文件

Question

所以，这个程序从 firebase 存储下载一个文件， 我的下载代码是：

private void downloadFiles(Context context, String fileName, String destinationDirectory, String url) {
    DownloadManager downloadManager = (DownloadManager) context.getSystemService(Context.DOWNLOAD_SERVICE);
    Uri uri = Uri.parse(url);
    DownloadManager.Request request = new DownloadManager.Request(uri);

    request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
    request.setDestinationInExternalFilesDir(context, String.valueOf(destinationDirectory), fileName);

    downloadManager.enqueue(request);
}

public void downloading(final String name) {
    downloadRef = storage.getInstance().getReference().child(name);
    downloadRef.getDownloadUrl().addOnSuccessListener(new OnSuccessListener<Uri>() {
        @Override
        public void onSuccess(Uri uri) {
            String url = uri.toString();
            downloadFiles(Main2Activity.this, name,  getApplicationContext().getExternalFilesDir(Environment.DIRECTORY_DOWNLOADS), url);
        }
    }).addOnFailureListener(new OnFailureListener() {
        @Override
        public void onFailure(@NonNull Exception e) {
            Toast.makeText(Main2Activity.this, "Failed!!!", Toast.LENGTH_LONG).show();
        }
    });
}

然后我想使用这个数据库，所以我尝试打开它：

database = SQLiteDatabase.openDatabase(myPath, null, 0);

我该如何解决这个问题？这对伙计们很有帮助。

Answer 1

我认为您的问题是可访问性。 这就是为什么我带回一个活动来获得用户的许可。 你测试这段代码

listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {

                if (ContextCompat.checkSelfPermission(MainActivity.this, Manifest.permission.READ_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED
                        && ContextCompat.checkSelfPermission(MainActivity.this, Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
                    ActivityCompat.requestPermissions(MainActivity.this, new String[] {Manifest.permission.READ_EXTERNAL_STORAGE,Manifest.permission.WRITE_EXTERNAL_STORAGE}, 1);
                } else {
                    Intent intent = new Intent(MainActivity.this, Main2Activity.class);
                    intent.putExtra("name", arrayList.get(position));
                    startActivity(intent);
                }

            }
        });

Answer 2

您正在使用Environment.getExternalStorageState()，它返回主要共享/外部存储媒体的当前状态。它不能用于获取路径作为任何文件的字符串。使用context.getExternalFilesDir(Environment.DIRECTORY_DOWNLOADS)获取Download目录路径的字符串值。