android – DownloadManager IllegalStateException在DIRECTORY_DOWNLOADS中创建下载

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我遇到的问题是,在极少数情况下,我的setDestinationInExternalPublicDir函数会产生以下堆栈跟踪：

Fatal Exception: java.lang.RuntimeException: Unable to start receiver com.onlinetvrecorder.otrapp2.listeners.DownloadUpdateReceiver: java.lang.IllegalStateException: Unable to create directory: /mnt/sdcard/Download
       at android.app.ActivityThread.handleReceiver(ActivityThread.java:2274)
       at android.app.ActivityThread.access$1500(ActivityThread.java:131)
       at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1272)
       at android.os.Handler.dispatchMessage(Handler.java:99)
       at android.os.Looper.loop(Looper.java:137)
       at android.app.ActivityThread.main(ActivityThread.java:4791)
       at java.lang.reflect.Method.invokeNative(Method.java)
       at java.lang.reflect.Method.invoke(Method.java:511)
       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
       at dalvik.system.NativeStart.main(NativeStart.java)
Caused by java.lang.IllegalStateException: Unable to create directory: /mnt/sdcard/Download
       at android.app.DownloadManager$Request.setDestinationInExternalPublicDir(DownloadManager.java:496)
       at com.myapp.Utils.download(SourceFile:752)
       at com.myapp.Receiver.onReceive(SourceFile:20)
       at android.app.ActivityThread.handleReceiver(ActivityThread.java:2267)
       at android.app.ActivityThread.access$1500(ActivityThread.java:131)
       at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1272)
       at android.os.Handler.dispatchMessage(Handler.java:99)
       at android.os.Looper.loop(Looper.java:137)
       at android.app.ActivityThread.main(ActivityThread.java:4791)
       at java.lang.reflect.Method.invokeNative(Method.java)
       at java.lang.reflect.Method.invoke(Method.java:511)
       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
       at dalvik.system.NativeStart.main(NativeStart.java)

我使用标准的环境常量告诉DownloadManager保存文件的位置.

android.app.DownloadManager dm = (android.app.DownloadManager) context.getSystemService(Context.DOWNLOAD_SERVICE);

DownloadManager.Request request = new DownloadManager.Request(Uri.parse("url.to.file.ext"));
request.setMimeType("mime/type");

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
    Utils.setDownloadRequestVisibility(request, android.app.DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
}

request.setDestinationInExternalPublicDir(Environment.DIRECTORY_DOWNLOADS, "file.ext");
request.setTitle(context.getString(R.string.download));

dm.enqueue(request);

如前所述,甚至可能有1％的用户没有收到此错误.可能是什么原因造成的？

在写我的问题的过程中,我注意到我可能刚刚解决了这个问题.我打算写一些有问题的设备模型,但在Crashlytics上显示的是“Unknown”.我点击了这一点,并揭示了以下模型：GI I9500 TMMARS.运行Android 4.

TMMARS似乎是 Trend Micro 的软件.

Trend Micro Mobile App Reputation Service or TMMARS is a cloud-based  service that automatically identifies mobile threats based on app  behaviors.

系统很可能不像App期望的那样,仅仅因为它是一个威胁检测环境.

崩溃报告示例：