如何在服务中的工作线程中显示敬酒? [英] How to show a toast from a worker thread inside a service?

问题描述

我正在使用 AlarmManager 唤醒设备并运行一些任务.这些是在 IntentService 内部完成的，因此在与主线程不同的线程上进行.工作完成后，我想敬酒.但是，我收到此日志警告，并且没有显示吐司:

I'm using AlarmManager to wake up the device and run some tasks. These are done inside an IntentService, so on a thread separate from the main one. When the work is done, I'd like to show a toast. However, I'm getting this log warning and no toast is shown:

W/MessageQueue﹕ Handler (android.os.Handler) {b12716d0} sending message to a Handler on a dead thread
    java.lang.RuntimeException: Handler (android.os.Handler) {b12716d0} sending message to a Handler on a dead thread
            at android.os.MessageQueue.enqueueMessage(MessageQueue.java:320)
            at android.os.Handler.enqueueMessage(Handler.java:626)
            at android.os.Handler.sendMessageAtTime(Handler.java:595)
            at android.os.Handler.sendMessageDelayed(Handler.java:566)
            at android.os.Handler.post(Handler.java:326)
            at android.widget.Toast$TN.hide(Toast.java:370)
            at android.app.ITransientNotification$Stub.onTransact(ITransientNotification.java:55)
            at android.os.Binder.execTransact(Binder.java:404)
            at dalvik.system.NativeStart.run(Native Method)

我知道关于此主题还有其他一些问题，但是我已经尝试了所有建议，但没有一个起作用.我正在使用:

I know there are a few other questions on this topic, but I've tried all the suggestions and none worked. I'm using:

Handler handler = new Handler();
handler.post(new Runnable()
{
    @Override
        public void run()
            {
                Toast.makeText(context, R.string.toast, Toast.LENGTH_LONG).show();
            }
});

我也尝试过:

Handler handler = new Handler(Looper.getMainLooper());

我仍然收到警告，没有吐司.

I'm still getting the warning and no toast.

通过我的 IntentService 展示此吐司的方式是什么?

What is the way to show this toast from my IntentService?

提前谢谢！

推荐答案

首先，您真的不应该从服务或用户不久前未发起的任何任务中发送Toast消息.否则，用户将不知道Toast的来源；她甚至无法确定它来自哪个应用程序-绝对令人困惑和不道德的做法.

First of all, you really shouldn't send Toast messages from a Service or from any task that wasn't initiated by the user a very short time ago. Otherwise the user won't know where the Toast is originating from; she can't even be sure from which app it comes - absolutely confusing and bad practice in general.

但是要回答您的问题，当您使用new Handler()创建处理程序时，它将附加到在其上创建的线程.因此，如果要从服务(从任何线程)向UI/主线程发布某些内容，则应在onCreate()方法中创建Handler.因为onCreate()，通常是任何Android回调方法，都是在UI线程上调用的.所以:

But to answer your question, when you create a Handler with new Handler() then it is attached to the thread it was created on. Thus, if you want to post something to the UI/main thread from a service (from any thread) then you should create the Handler in, for instance, the onCreate() method; because onCreate(), and usually any Android callback method, is called on the UI thread. So:

public class MyService extends Service {

    private Handler mMainThreadHandler;

    @Override
    public void onCreate() {
        mMainThreadHandler = new Handler();
    }

    [...]
}

或者，您想要创建一个附加到UI线程的处理程序，并且不想在哪里创建它，那么请使用new Handler(Looper.getMainLooper()).这样，它就可以连接到主弯针上了.这是主线程的循环程序.

Or, of you want to create a Handler that is attached to the UI thread and don't want to care about where it is created then use new Handler(Looper.getMainLooper()). This way it is attached to the main looper; which is the looper of the main thread.

public class MyService extends Service {

    private Handler mMainThreadHandler = new Handler(Looper.getMainLooper());

    [...]
}

我知道您写过它，您曾经尝试过；但应该可以.

I know you wrote you tried it; but it should work.

但是，我建议您不要理会Handlers.改用Needle. Needle是适用于Android的简单而强大的多线程库.有了它，您可以说出类似的话:

Though, what I would recommend you is not to bother with Handlers; use Needle instead. Needle is a simple and powerful multithreading library for Android. With it, you can say things like:

Needle.onMainThread().execute(new Runnable() {
    @Override
    public void run() {
        // e.g. change one of the views
    }
});

在GitHub上进行检查: https://github.com/ZsoltSafrany/needle

Check it out on GitHub: https://github.com/ZsoltSafrany/needle

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