Android Studio开发时候下载文件没有权限

问题遇到的现象和发生背景

下载文件没有权限加了

没有用

问题相关代码，请勿粘贴截图

private static final String savePath = "/sdcard/ext/";

private static final String saveFileName = savePath + "ZZOAClient.apk";
                HttpURLConnection conn = (HttpURLConnection) url.openConnection();
                conn.connect();
                int length = conn.getContentLength();
                InputStream is = conn.getInputStream();
                File file = new File(savePath);
                if (!file.exists()) {
                    file.mkdir();
                }
                String apkFile = saveFileName;
                File ApkFile = new File(apkFile);
                FileOutputStream fos = new FileOutputStream(ApkFile);
                int count = 0;
                byte buf[] = new byte[1024];
                do {
                    int numread = is.read(buf);
                    count += numread;
                    progress = (int) (((float) count / length) * 100);
                    //更新进度
                    updateHandler.sendEmptyMessage(DOWN_UPDATE);
                    if (numread <= 0) {
                        //下载完成通知安装
                        updateHandler.sendEmptyMessage(DOWN_OVER);
                        break;
                    }
                    fos.write(buf, 0, numread);
                } while (!interceptFlag);//点击取消就停止下载.
                fos.close();
                is.close();

运行结果及报错内容

我的解答思路和尝试过的方法

我想要达到的结果

读写权限申请了吗？

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.MANAGE_EXTERNAL_STORAGE"
    tools:ignore="ScopedStorage" /> <!--安卓11需要申请该权限-->