Java 如何在android应用程序中获得权限？

我在手机上获取从raw保存文件的权限时遇到问题。我已在清单中说明：

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

要检查权限，请执行以下操作：

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
        );
    }
}

当我试图通过单击应用程序中的按钮保存此文件时，我收到错误：

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

---

怎么了？

我认为这是你的问题：

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

请使用以下选项：

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

---

您只有

/storage/emulated/0/Download/testsound.mp3

的权限，而没有

/storage/emulated/0/Downloadtestsound.mp3

我相信这是您的问题：

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

请使用以下选项：

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

您只有

/storage/emulated/0/Download/testsound.mp3

权限，而没有

/storage/emulated/0/Downloadtestsound.mp3

放置“/”在

filename

和

downloadsDirectoryPath

之间，这就是它给出错误的原因。要测试您是否没有获得权限，请转到“设置”并在那里选中“手动授予权限”，然后重新启动

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();
                }
            }
        }
}

});

将“/”放在

filename

和

downloadsDirectoryPath

之间，这就是它给出错误的原因。若要测试您是否未获得权限，请转到“设置”并在那里检查手动授予权限，然后再次启动

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();
                }
            }
        }
}

});

---

下载文件夹后是否缺少斜杠？换句话说，您没有根访问权限？下载文件夹后是否缺少斜杠？换句话说，您没有根访问权限hmmm，这会将错误更改为/storage/emulated/0/Download/testsound.mp3:打开失败：EACCES（权限被拒绝）@Johnystrawits您能尝试将您的目标sdk版本更改为21并再次检查吗？我将目标sdk设置为21，但仍然收到此错误：/Hmmm，将错误更改为/storage/simulated/0/Download/testsound.mp3:open失败：EACCES（权限被拒绝）@Johnystrawits能否尝试将您的目标sdk版本更改为21并再次检查？我已将目标sdk设置为21，但仍然出现以下错误：/