為什么我的Android不讀取“下載”文件夾中的該文件？

Question

我的下載文件夾中有一個名為“ mysimulation.txt”的文件。

            Scanner input = new Scanner(System.in);
            String filename = "/mysimulation.txt";

            try {
                input = new Scanner(new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS) + filename));
                Toast.makeText(this, "found", Toast.LENGTH_SHORT).show();
            } catch (FileNotFoundException e) {
                Toast.makeText(this, "not found " + Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS), Toast.LENGTH_LONG).show();
            }

為什么我的手機無法讀取“下載”文件夾中的該文件？ 我收到未找到文件的異常。

Answer 1

對於任何大於android 6.0（masshmallow）的android。 將以下代碼添加到您的Java代碼中以授予讀寫權限：

File file = new File(path);
 ActivityCompat.requestPermissions(this,new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE, Manifest.permission.READ_EXTERNAL_STORAGE},
                            123);
 //Check if the file is writable or readable (.canRead()) 
 Toast.makeText(this, file.canWrite() ? "y" : "no ", Toast.LENGTH_SHORT).show();