下载apk，没有这样的文件或目录错误..

Question

我正在创建一个从网络服务器下载apk文件然后安装它的应用程序，但我遇到了问题，当我点击下载时，进度条会比较但不会改变，并且在Android中Monitor比较一下：

我正在使用带有android 7.1.1的avd，我将尝试使用marshmallow。 这是代码：

    try {
    if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {
   String sdPath = Environment.getExternalStorageDirectory() + "/";

                    mSavePath = sdPath + "updateDownload";
                    File dir = new File(mSavePath);

                    if (!dir.exists())
                        if (dir.mkdir())
                            Log.d(TAG, "mkdir success");
                        else
                            Log.d(TAG, "mkdir failed!");

                    HttpURLConnection conn = (HttpURLConnection) new URL(path).openConnection();
                    conn.connect();

                    InputStream is = conn.getInputStream();

                    int length = conn.getContentLength();

                    File apkFile = new File(mSavePath, version_name);

                    FileOutputStream fos = new FileOutputStream(apkFile);

                    int count = 0;
                    byte[] buffer = new byte[1024];
                    while (!isCancel) {
                        int numread = is.read(buffer);
                        count += numread;
                        mProgress = (int) ((float) (count / length) * 100);

                        mUpdateProgressHandler.sendEmptyMessage(DOWNLOADING);
                        if (numread < 0) {
                            mUpdateProgressHandler.sendEmptyMessage(DOWNDLOAD_FINISHED);
                            break;
                        }
                        fos.write(buffer, 0, numread);

                    }
                    fos.close();
                    is.close();

                } else {
                    Log.d(TAG, " Media not mounted");
                }


            } catch (Exception e) {
                e.printStackTrace();
            }

Answer 1

Android在Android 6.0之后需要运行时权限 参考https://developer.android.com/training/permissions/requesting.html