我在网上彻底搜索以找到答案，但没有结果。

我在我的 Android 应用程序中实现了一些“首选项”，包括将文件保存在您想要的任何位置的能力。

如果我在所谓的“集成sdcard”上选择一个路径，一切都OK。但我也有一个“真正的”外部 sdcard，它(在我的例子中)安装在 /storage/sdcard1 符号链接(symbolic link)到 /extSdCard 和 /mnt/extSdCard (虽然“内部”sdcard 是 /storage/sdcard0，带有指向 /sdcard 和 /mnt/sdcard 的符号链接(symbolic link))。

在 ICS 上，我在 /emmc 有外部链接，还有一些我不记得的链接。

问题是，如果我选择指向此 extSdCard 的路径，应用程序会创建文件夹结构，但不会写入下载的文件，以“SecurityException”结尾“目的地必须是在外部存储上”。

但是这个路径在外部存储上!更多:如果写权限有问题，为什么要创建文件夹？ (android.permission.WRITE_EXTERNAL_STORAGE 存在于 list 中)。

很可能我做错了什么；或者可能是一些错误？

eclipse 日志:

11-30 11:58:29.143: D/ShareActivity(24752): doInBackground...
11-30 11:58:33.813: D/ShareActivity(24752): The response is: 200
11-30 11:58:50.283: D/ShareActivity(24752): location: Downloads
11-30 11:58:50.443: D/ShareActivity(24752): User defined folders created
11-30 11:58:50.443: D/ShareActivity(24752): path: /storage/sdcard1/temp
11-30 11:59:07.053: D/ShareActivity(24752): downloadUri: file:/storage/sdcard1/temp/test.3gpp
11-30 11:59:07.313: D/AndroidRuntime(24752): Shutting down VM
11-30 11:59:07.318: W/dalvikvm(24752): threadid=1: thread exiting with uncaught exception (group=0x41ce3300)
11-30 11:59:07.318: E/AndroidRuntime(24752): FATAL EXCEPTION: main
11-30 11:59:07.318: E/AndroidRuntime(24752): java.lang.SecurityException: Destination must be on external storage: file:/storage/sdcard1/temp/test.3gpp
11-30 11:59:07.318: E/AndroidRuntime(24752):    at android.os.Parcel.readException(Parcel.java:1425)
11-30 11:59:07.318: E/AndroidRuntime(24752):    at android.database.DatabaseUtils.readExceptionFromParcel(DatabaseUtils.java:188)
11-30 11:59:07.318: E/AndroidRuntime(24752):    at android.database.DatabaseUtils.readExceptionFromParcel(DatabaseUtils.java:140)
11-30 11:59:07.318: E/AndroidRuntime(24752):    at android.content.ContentProviderProxy.insert(ContentProviderNative.java:420)
11-30 11:59:07.318: E/AndroidRuntime(24752):    at android.content.ContentResolver.insert(ContentResolver.java:864)
11-30 11:59:07.318: E/AndroidRuntime(24752):    at android.app.DownloadManager.enqueue(DownloadManager.java:904)
11-30 11:59:07.318: E/AndroidRuntime(24752):    at dentex.youtube.downloader.ShareActivity$AsyncDownload$1$1.onClick(ShareActivity.java:269)
11-30 11:59:07.318: E/AndroidRuntime(24752):    at com.android.internal.app.AlertController$ButtonHandler.handleMessage(AlertController.java:166)
11-30 11:59:07.318: E/AndroidRuntime(24752):    at android.os.Handler.dispatchMessage(Handler.java:99)
11-30 11:59:07.318: E/AndroidRuntime(24752):    at android.os.Looper.loop(Looper.java:137)
11-30 11:59:07.318: E/AndroidRuntime(24752):    at android.app.ActivityThread.main(ActivityThread.java:4931)
11-30 11:59:07.318: E/AndroidRuntime(24752):    at java.lang.reflect.Method.invokeNative(Native Method)
11-30 11:59:07.318: E/AndroidRuntime(24752):    at java.lang.reflect.Method.invoke(Method.java:511)
11-30 11:59:07.318: E/AndroidRuntime(24752):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:791)
11-30 11:59:07.318: E/AndroidRuntime(24752):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:558)
11-30 11:59:07.318: E/AndroidRuntime(24752):    at dalvik.system.NativeStart.main(Native Method)
11-30 11:59:09.248: I/Process(24752): Sending signal. PID: 24752 SIG: 9

相关代码:

lv.setOnItemClickListener(new OnItemClickListener() {

            private File userFolder;

                public void onItemClick(AdapterView<?> parent, View view, int position, long id) {

                String location = settings.getString("download_locations", "Downloads");
                Log.d(DEBUG_TAG, "location: " + location);

                boolean userLocationEnabled = settings.getBoolean("enable_user_location", false);

                if (userLocationEnabled == false) {
                    if (location.equals("DCIM") == true) {
                        path = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DCIM);
                    }
                    if (location.equals("Movies") == true) {
                        path = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_MOVIES);
                    } 
                    if (location.equals("Downloads") == true) {
                        path = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS);
                    }
                    Log.d(DEBUG_TAG, "path: " + path);
                } else {
                        userFolder = new File(settings.getString("user_location", ""));
                        path = userFolder;
                }

                Log.d(DEBUG_TAG, "path: " + path.toString());

                pos = position;
                AlertDialog.Builder helpBuilder = new AlertDialog.Builder(ShareActivity.this);

                helpBuilder.setIcon(android.R.drawable.ic_dialog_info);
                helpBuilder.setTitle("Confirm Download for:");
                helpBuilder.setMessage(" *** msg *** ");

                helpBuilder.setPositiveButton("Download here", new DialogInterface.OnClickListener() {

                    @TargetApi(11)
                    public void onClick(DialogInterface dialog, int which) {
                        mLink = links[pos];
                        downloadManager = (DownloadManager) getSystemService(DOWNLOAD_SERVICE);

                        Request request = new Request(Uri.parse(mLink));
                        uri = Uri.parse(path.toURI() + title + "." + mExt);
                        Log.d(DEBUG_TAG, "downloadUri: " + uri);
                        request.setDestinationUri(uri);
                        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
                            request.allowScanningByMediaScanner();
                            request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
                        }

                        if (isExternalStorageWritable() == true) {
                            enqueue = downloadManager.enqueue(request);
                        }
                    }
                });

                helpBuilder.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
                   //...
                });

                AlertDialog helpDialog = helpBuilder.create();
                helpDialog.show();

            }
});

最佳答案

根据 THIS ARTICLE作者:Jeremy Meiss (jerdog) 和 THIS LINK通过 Chainfire，目前这种行为应该是“正常的”。应该需要 WRITE_MEDIA_STORAGE 权限，但这仅授予系统应用程序。

作为一种解决方法，在我的 Activity 中，我像这样(在伪代码中)处理此 SecurityException:

Intent intent = new Intent(MyActivity.this, DownloadsService.class);

try {
    intent.putExtra("COPY", false);
    enqueue = dm.enqueue(request);
    Log.d(DEBUG_TAG, "_ID " + enqueue + " enqueued");
} catch (SecurityException e) {
    Log.w(DEBUG_TAG, e.getMessage());

    // handle the path on etxSdCard here:
    showSomeInfo();
    intent.putExtra("COPY", true);
    tempDownloadToSdcard(request);
}

startService(intent);

在 DownloadsService 中，我有一个 BroadcastReceiver，我在其中处理完成的下载； 在其 onStartCommand 中，我将 bool 值额外检索为:

doCopy = intent.getBooleanExtra("COPY", false);

然后在接收器内部:

if (doCopy) copyFileToExtSdCard();

希望这能澄清问题并有所帮助。

关于安卓:安全异常: "destination must be on external storage"，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/13646669/