在发布模式下，Xamarin Android 应用闪退（Parse.Android SDK）

Question

我正在开发一个使用Parse Android SDK的应用程序。在调试模式下，应用程序可以正常工作，但是当我在发布模式下进行编译时，会出现以下错误。错误发生在执行Parse查询时，而不是在初始化Parse时。

[MonoDroid] UNHANDLED EXCEPTION: System.NullReferenceException: Object reference not set to an instance of an object
[MonoDroid]   at Parse.PlatformHooks+<RequestAsync>d__19.MoveNext () [0x00000] in <filename unknown>:0 
[MonoDroid] --- End of stack trace from previous location where exception was thrown ---
[MonoDroid]   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () [0x00000] in <filename unknown>:0 
[MonoDroid]   at Parse.Internal.InternalExtensions+<>c__DisplayClass7`1[System.Tuple`2[System.Net.HttpStatusCode,System.Collections.Generic.IDictionary`2[System.String,System.Object]]].<OnSuccess>b__6 (System.Threading.Tasks.Task t) [0x00000] in <filename unknown>:0 
[MonoDroid]   at System.Threading.Tasks.TaskActionInvoker+FuncTaskInvoke`1[System.Threading.Tasks.Task`1[System.Tuple`2[System.Net.HttpStatusCode,System.Collections.Generic.IDictionary`2[System.String,System.Object]]]].Invoke (System.Threading.Tasks.Task owner, System.Object state, System.Threading.Tasks.Task context) [0x00000] in <filename unknown>:0 
[MonoDroid]   at System.Threading.Tasks.Task.InnerInvoke () [0x00000] in <filename unknown>:0 
[MonoDroid]   at System.Threading.Tasks.Task.ThreadStart () [0x00000] in <filename unknown>:0 
[MonoDroid] --- End of stack trace from previous location where exception was thrown ---
[MonoDroid]   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () [0x00000] in <filename unknown>:0 
[MonoDroid]   at Parse.Internal.InternalExtensions+<>c__DisplayClass7`1[System.Collections.Generic.IEnumerable`1[Parse.ParseObject]].<OnSuccess>b__6 (System.Threading.Tasks.Task t) [0x00000] in <filename unknown>:0 
[MonoDroid]   at System.Threading.Tasks.TaskActionInvoker+FuncTaskInvoke`1[System.Threading.Tasks.Task`1[System.Collections.Generic.IEnumerable`1[Parse.ParseObject]]].Invoke (System.Threading.Tasks.Task owner, System.Object state, System.Threading.Tasks.Task context) [0x00000] in <filename unknown>:0 
[MonoDroid]   at System.Threading.Tasks.Task.InnerInvoke () [0x00000] in <filename unknown>:0 
[MonoDroid]   at System.Threading.Tasks.Task.ThreadStart () [0x00000] in <filename unknown>:0 
[MonoDroid] --- End of stack trace from previous location where exception was thrown ---
[MonoDroid]   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () [0x00000] in <filename unknown>:0 
[MonoDroid]   at System.Runtime.CompilerServices.TaskAwaiter`1[System.Collections.Generic.IEnumerable`1[Parse.ParseObject]].GetResult () [0x00000] in <filename unknown>:0 
[MonoDroid]   at ParseDAL.ParseCaller+<Init>c__async0.MoveNext () [0x00000] in <filename unknown>:0 
[mono] 
[mono] Unhandled Exception:
[mono] System.NullReferenceException: Object reference not set to an instance of an object
[mono]   at Parse.PlatformHooks+<RequestAsync>d__19.MoveNext () [0x00000] in <filename unknown>:0 
[mono] --- End of stack trace from previous location where exception was thrown ---
[mono]   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () [0x00000] in <filename unknown>:0 
[mono]   at Parse.Internal.InternalExtensions+<>c__DisplayClass7`1[System.Tuple`2[System.Net.HttpStatusCode,System.Collections.Generic.IDictionary`2[System.String,System.Object]]].<OnSuccess>b__6 (System.Threading.Tasks.Task t) [0x00000] in <filename unknown>:0 
[mono]   at System.Threading.Tasks.TaskActionInvoker+FuncTaskInvoke`1[System.Threading.Tasks.Task`1[System.Tuple`2[System.Net.HttpStatusCode,System.Collections.Generic.IDictionary`2[System.String,System.Object]]]].Invoke (System.Threading.Tasks.Task owner, System.Object state, System.Threading.Tasks.Task context) [0x00000] in <filename unknown>:0 
[mono]   at System.Threading.Tasks.Task.InnerInvoke 
[mono-rt] [ERROR] FATAL UNHANDLED EXCEPTION: System.NullReferenceException: Object reference not set to an instance of an object
[mono-rt]   at Parse.PlatformHooks+<RequestAsync>d__19.MoveNext () [0x00000] in <filename unknown>:0 
[mono-rt] --- End of stack trace from previous location where exception was thrown ---
[mono-rt]   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () [0x00000] in <filename unknown>:0 
[mono-rt]   at Parse.Internal.InternalExtensions+<>c__DisplayClass7`1[System.Tuple`2[System.Net.HttpStatusCode,System.Collections.Generic.IDictionary`2[System.String,System.Object]]].<OnSuccess>b__6 (System.Threading.Tasks.Task t) [0x00000] in <filename unknown>:0 
[mono-rt]   at System.Threading.Tasks.TaskActionInvoker+FuncTaskInvoke`1[System.Threading.Tasks.Task`1[System.Tuple`2[System.Net.HttpStatusCode,System.Collections.Generic.IDictionary`2[System.String,System.Object]]]].Invoke (System.Threading.Tasks.Task owner, System.Object state, System.Threading.Tasks.Task context) [0x00000] in <filename unknown>:0 
[mono-rt]   at System.Threading.Tasks.Task

以下是代码：

ParseClient.Initialize("App Id", "Dot Net Key");
var userQuery = ParseObject.GetQuery ("Table Name");
var userData = await userQuery.FindAsync ();
foreach (var ud in userData) {
    Console.WriteLine ("UD " + ud.Get<string>(Constants.COL_USER_NAME));
}

我尝试了所有的链接选项，包括“不链接”，“链接所有程序集”和“链接SDK程序集”。但应用程序仍然崩溃。

- Basit ZIa

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当我禁用优化时，没有任何变化，感谢提示。 - Swift Sharp

@SeeSharp 当我以“调试”模式编译后端代码DLL并在前端项目中引用它们时，无论是在发布模式还是调试模式下都可以正常工作。 这个异常有时会在我们向服务器发送请求（响应挂起）时发生，而网络断开或服务器无法访问。我不知道如何处理它，或者停止崩溃。 - Basit ZIa

请确保您已在发布模式下添加了“Internet”权限。在调试模式下，Internet权限会自动添加到清单文件中。 - Basit ZIa

@ Basit Zia，你的想法真的很有效，兄弟，谢谢你。 - Swift Sharp

顺便说一句，如果你想把评论作为答案发布。 - Swift Sharp

Answer 1

这个异常是由于网络问题而不是调试/发布构建引起的。在调试模式下，INTERNET权限会自动添加到清单文件中，但在发布模式下则不会。因此，请在清单文件中添加此权限。

<uses-permission android:name="android.permission.INTERNET" />

在发布模式中将不会再出现这个异常。

在发送请求之前，我们仍然需要检查网络是否可用以解析数据。

- Basit ZIa

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太棒了！你救了我的一天。 - Anees Deen

我也可以。 - Atif