android – 使用FileProvider时没有找到处理Intent的Activity

// auto register for the complete download
     activity.registerReceiver(onComplete,new IntentFilter(DownloadManager.ACTION_DOWNLOAD_COMPLETE));



 // Download the file through DownloadManager
 String destination = Environment.getExternalStorageDirectory() + "/";
    String fileName = "myfile.apk";
    destination += fileName;
    final Uri uri = Uri.parse("file://" + destination);
    DownloadManager.Request request = new  DownloadManager.Request(Uri.parse(apkUrl));
    request.setDescription("description");
    request.setTitle("title");
    request.setDestinationUri(uri);
    final DownloadManager manager = (DownloadManager) activity.getSystemService(Context.DOWNLOAD_SERVICE);
    final long downloadId = manager.enqueue(request);

onComplete = new broadcastReceiver() {
      public void onReceive(Context ctxt,Intent intent) {

          Intent install = new Intent(Intent.ACTION_VIEW);
          // BEFORE working doing this
          //install.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
          //install.setDataAndType(uri,//    manager.getMimeTypeForDownloadedFile(downloadId));

          // Using file provider it doesnt work
          Uri apkUri = FileProvider.getUriForFile(AutoUpdate.this,"com.myapp",file);
                install.setDataAndType(apkUri,manager.getMimeTypeForDownloadedFile(downloadId));
          activity.startActivity(install);
          activity.unregisterReceiver(this);

      }
    };

Android清单：

<provider
            android:name="android.support.v4.content.FileProvider"
            android:authorities="com.myapp"
            android:exported="false"
            android:grantUriPermissions="true">
            <Meta-data
                android:name="android.support.FILE_PROVIDER_PATHS"
                android:resource="@xml/provider_paths"/>
        </provider>

Provider_path(很抱歉由于某种原因因此削减了路径标记)

external-path name=”myfolder” path=”.”/>

当文件完成下载时,会调用onComplete,但是活动不会启动：

No Activity found to handle Intent { act=android.intent.action.VIEW
dat=content://com.myapp/myfolder/myfile.apk
typ=application/vnd.android.package-archive flg=0x4000000 }

使用普通文件时：//确实有效

使用文件提供程序时是否有一些我缺少的东西？活动是否因为找不到文件而无法启动？
我需要额外的许可吗？ (目前我在外部存储上有INTERNET,READ和WRITE)