如何在Android应用中获取许可？

Question

我在获取权限以从手机上的原始文件保存文件时遇到问题。 我明确地表明了这一点：

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

在我使用onclick的Java中，我具有保存文件的功能

saveTestButton.setOnClickListener(new View.OnClickListener() {

        public void onClick(View v) {

                InputStream in = null;
                FileOutputStream fout = null;
                try {
                    in = getResources().openRawResource(R.raw.testsound);
                    String downloadsDirectoryPath = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS).getAbsolutePath();
                    String filename = "testsound.mp3";
                    fout = new FileOutputStream(new File(downloadsDirectoryPath + filename));

                    final byte data[] = new byte[1024];
                    int count;
                    while ((count = in.read(data, 0, 1024)) != -1) {
                        fout.write(data, 0, count);
                    }
                } catch (FileNotFoundException e) {
                    e.printStackTrace();
                } catch (IOException e) {
                    e.printStackTrace();
                } finally {
                    if (in != null) {
                        try {
                            in.close();
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    }
                    if (fout != null) {
                        try {
                            fout.close();
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    }
                }
        }

    });

并检查权限：

private static final int REQUEST_EXTERNAL_STORAGE = 1;
    private static String[] PERMISSIONS_STORAGE = {
            Manifest.permission.READ_EXTERNAL_STORAGE,
            Manifest.permission.WRITE_EXTERNAL_STORAGE
    };
public static void verifyStoragePermissions(Activity activity) {
    // Check if we have write permission
    int permission = ActivityCompat.checkSelfPermission(activity, Manifest.permission.WRITE_EXTERNAL_STORAGE);

    if (permission != PackageManager.PERMISSION_GRANTED) {
        // We don't have permission so prompt the user
        ActivityCompat.requestPermissions(
                activity,
                PERMISSIONS_STORAGE,
                REQUEST_EXTERNAL_STORAGE
        );
    }
}

当我尝试通过单击应用程序中的按钮保存此文件时，出现错误：

W / System.err：java.io.FileNotFoundException：/storage/emulated/0/Downloadtestsound.mp3：打开失败：EACCES（权限被拒绝）

怎么了？

Answer 1

我相信这是您的问题：

fout = new FileOutputStream(new File(downloadsDirectoryPath + filename));

请改用以下内容：

fout = new FileOutputStream(new File(downloadsDirectoryPath , filename));

您仅具有/storage/emulated/0/Download/testsound.mp3权限，而没有/storage/emulated/0/Downloadtestsound.mp3权限

Answer 2

在filename和downloadsDirectoryPath之间放置“ /”，这就是错误提示的原因。如果您没有权限，请进行测试，然后转到设置并手动检查那里的权限并再次启动。

public void onClick(View v) {

        InputStream in = null;
        FileOutputStream fout = null;
        try {
            in = getResources().openRawResource(R.raw.testsound);
            String downloadsDirectoryPath = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS).getAbsolutePath();
            String filename = "testsound.mp3";
            fout = new FileOutputStream(new File(downloadsDirectoryPath + "/"+filename));

            final byte data[] = new byte[1024];
            int count;
            while ((count = in.read(data, 0, 1024)) != -1) {
                fout.write(data, 0, count);
            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (in != null) {
                try {
                    in.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (fout != null) {
                try {
                    fout.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
}

});