我在Lollipop及以下版本中发生了奇怪的崩溃。尝试从服务器下载文件时出现安全异常，但在运行Marshmallow及更高版本的设备中应用程序不会崩溃。 Logcat：
由以下原因引起：java.lang.SecurityException：需要WRITE_EXTERNAL_STORAGE权限才能使用DESTINATION_FILE_URI：uid 10229没有android.permission.WRITE_EXTERNAL_STORAGE。
在App的grandle中，我使用
targetSdkVersion 22
在我们首次按下Google控制台以定位最新的sdk版本后，它会发生变化，但目前仍保持为22，因此不需要运行时权限。
此外，在App的清单中，我们声明了App的许可。
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.DOWNLOAD_WITHOUT_NOTIFICATION" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
另外，在
DownloadManager内使用AsynckTask的代码：try {
String dirPath = String.format("%5$s/%1$s/Resources/%2$s/%3$s/%4$s/", userID, resource.getiD(), filePackage.getiD(), language, dir.getCanonicalPath());
File makeDirs = new File(dirPath);
makeDirs.mkdirs();
} catch (Exception ex) {
ex.printStackTrace();
}
this.downloadManager = (DownloadManager) getApplicationContext().getSystemService(DOWNLOAD_SERVICE);
DownloadManager.Request request = new DownloadManager.Request(url);
request.setDestinationInExternalFilesDir(getApplicationContext(), null, filePath);
request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_HIDDEN);
request.setVisibleInDownloadsUi(false);
downloadID = downloadManager.enqueue(request);
同样，只有在OS版本5.0.2的Galaxy A5，运行带有
Lollipop的Samsung Galaxy S6的模拟器和运行Kitkat 4.4.4 HTC One的模拟器中，才观察到此崩溃。完整的
stack trace： java.lang.RuntimeException: Unable to start activity ComponentInfo{...players.PDFViewer}: java.lang.SecurityException: need WRITE_EXTERNAL_STORAGE permission to use DESTINATION_FILE_URI: uid 10229 does not have android.permission.WRITE_EXTERNAL_STORAGE.
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2808)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2873)
at android.app.ActivityThread.access$900(ActivityThread.java:181)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1482)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:145)
at android.app.ActivityThread.main(ActivityThread.java:6145)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1399)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1194)
Caused by: java.lang.SecurityException: need WRITE_EXTERNAL_STORAGE permission to use DESTINATION_FILE_URI: uid 10229 does not have android.permission.WRITE_EXTERNAL_STORAGE.
at android.os.Parcel.readException(Parcel.java:1540)
at android.database.DatabaseUtils.readExceptionFromParcel(DatabaseUtils.java:185)
at android.database.DatabaseUtils.readExceptionFromParcel(DatabaseUtils.java:137)
at android.content.ContentProviderProxy.insert(ContentProviderNative.java:475)
at android.content.ContentResolver.insert(ContentResolver.java:1260)
at android.app.DownloadManager.enqueue(DownloadManager.java:1336)
at de.imsystems.crmmobile.players.PDFViewer.onCreate(PDFViewer.java:104)
at android.app.Activity.performCreate(Activity.java:6374)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1119)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2752)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2873)
at android.app.ActivityThread.access$900(ActivityThread.java:181)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1482)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:145)
at android.app.ActivityThread.main(ActivityThread.java:6145)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1399)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1194)
如果您有任何想法，请分享，谢谢。
最佳答案
最终，这篇文章WRITE_EXTERNAL_STORAGE not working on lollipop even though it's set in the manifest帮助了我。我所做的就是像这样更改AndroidManifest.xml文件中的权限：
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" android:maxSdkVersion="26" tools:replace="android:maxSdkVersion"/>
现在，该应用程序不会崩溃！
关于android - targetSdkVersion低于22的Download Manager的安全异常(exception)，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/47035050/