如何显示在Android的对话框没有活动背景？

问题描述

这似乎应该是简单的，但我没有找到答案的任何地方。我有一个Android应用程序在后台执行网络任务。如果错误回来，我要显示一个错误对话框。当任务返回时，我不知道哪个活动是在前台。根据this帖子，看起来我们不能使用应用程序上下文来显示一个对话框（实际上我得到的崩溃，如果我尝试）。

所以，我怎么能得到当前活动的背景下？同样，接收器在网络任务中的应用程序上下文中运行，而不是在一个特定的活动。任何其他的想法？

编辑：我要澄清。我不想，如果我不是前台应用程序显示一个错误对话框。我只关心在我们的应用程序是在前台，现在的情况。

解决方案

请只有这样做，如果你知道用户主动使用你的应用程序。如果你打断他们在别的中间（玩游戏，看电影，读一本书）的用户将非常非常恼火。

您不知道。至多，你让当前的活动知道它需要做一些事情。

一种可能是使用一个有序的广播，使的如果的有前景的活动，它得到控制，否则你养通知来让用户了解这个问题，没有弹出一个对话框。接收有序广播的活动可以显示一个 AlertDialog 或以其他方式让用户知道这个问题。我写了一篇关于如何做到这一点在一篇博客文章细节（和一本书章节，对于这个问题），和的展示该技术的示例应用程序。

或者，有服务电话 startActivity（）启动的。

This seems like it should be simple, but I'm not finding an answer anywhere. I have an Android application that performs network tasks in the background. If an error comes back, I want to display an error dialog. When the task returns, I don't know which Activity is in the foreground. Based on this post, it looks like we can't use the application context to display a dialog (and indeed I do get the crash if I try).

So how can I get the context of the current activity? Again, the receiver for the network task is running in the Application context, not in a particular Activity. Any other ideas?

Edit: I should clarify. I don't want to display an error dialog if I'm not the foreground application. I'm only interested in the case where our app is in the foreground for now.

解决方案

Please only do this if you know that the user is actively using your application. The user will be very very annoyed if you interrupt them in the middle of something else (playing a game, watching a movie, reading a book).

You don't. At most, you let the current activity know that it needs to do something.

One possibility is to use an ordered broadcast, so if you have a foreground activity, it gets control, otherwise you raise a Notification to let the user know about the problem without popping a dialog. The activity that receives the ordered broadcast can display an AlertDialog or otherwise let the user know about the problem. I wrote about the details of how to do this in a blog post (and a book chapter, for that matter), and here is a sample application demonstrating the technique.

Or, have the service call startActivity() to start up a dialog-themed activity.

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