如何处理屏幕方向变化时进度对话框和背景线程活跃？ [英] How to handle screen orientation change when progress dialog and background thread active?

问题描述

我的程序会在后台线程中的一些网络活动。在开始之前，它会弹出一个进度对话框。该对话框被关闭的处理程序。这一切工作正常，除了当屏幕方向的变化而对话是向上（与后台线程是怎么回事）。在这一点上无论是程序崩溃或死锁，或进入一个怪异的阶段，即应用程序不会直到所有的线程都被杀死在所有的工作。

My program does some network activity in a background thread. Before starting, it pops up a progress dialog. The dialog is dismissed on the handler. This all works fine, except when screen orientation changes while the dialog is up (and the background thread is going). At this point the app either crashes, or deadlocks, or gets into a weird stage where the app does not work at all until all the threads have been killed.

如何处理屏幕方向变化的优雅？

How can I handle the screen orientation change gracefully?

下面的示例code匹配大概是我真正的程序操作：

The sample code below matches roughly what my real program does:

public class MyAct extends Activity implements Runnable {
    public ProgressDialog mProgress;

    // UI has a button that when pressed calls send

    public void send() {
         mProgress = ProgressDialog.show(this, "Please wait", 
                      "Please wait", 
                      true, true);
        Thread thread = new Thread(this);
        thread.start();
    }

    public void run() {
        Thread.sleep(10000);
        Message msg = new Message();
        mHandler.sendMessage(msg);
    }

    private final Handler mHandler = new Handler() {
        @Override
        public void handleMessage(Message msg) {
            mProgress.dismiss();
        }
    };
}

堆栈：

E/WindowManager(  244): Activity MyAct has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView@433b7150 that was originally added here
E/WindowManager(  244): android.view.WindowLeaked: Activity MyAct has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView@433b7150 that was originally added here
E/WindowManager(  244):     at android.view.ViewRoot.<init>(ViewRoot.java:178)
E/WindowManager(  244):     at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:147)
E/WindowManager(  244):     at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:90)
E/WindowManager(  244):     at android.view.Window$LocalWindowManager.addView(Window.java:393)
E/WindowManager(  244):     at android.app.Dialog.show(Dialog.java:212)
E/WindowManager(  244):     at android.app.ProgressDialog.show(ProgressDialog.java:103)
E/WindowManager(  244):     at android.app.ProgressDialog.show(ProgressDialog.java:91)
E/WindowManager(  244):     at MyAct.send(MyAct.java:294)
E/WindowManager(  244):     at MyAct$4.onClick(MyAct.java:174)
E/WindowManager(  244):     at android.view.View.performClick(View.java:2129)
E/WindowManager(  244):     at android.view.View.onTouchEvent(View.java:3543)
E/WindowManager(  244):     at android.widget.TextView.onTouchEvent(TextView.java:4664)
E/WindowManager(  244):     at android.view.View.dispatchTouchEvent(View.java:3198)

我试图驳回的onSaveInstanceState进度对话框，但只是prevents立即崩溃。后台线程仍在继续，而UI是在部分地拉伸状态。需要把它再次开始工作之前杀死整个应用程序。

I have tried to dismiss the progress dialog in onSaveInstanceState, but that just prevents an immediate crash. The background thread is still going, and the UI is in partially drawn state. Need to kill the whole app before it starts working again.

推荐答案

当您切换方向，Android将创建一个新的视图。你可能得到崩溃，因为你的后台线程试图更改旧的状态。 （这也可能遇到麻烦，因为你的后台线程不在UI线程上）

When you switch orientations, Android will create a new View. You're probably getting crashes because your background thread is trying to change the state on the old one. (It may also be having trouble because your background thread isn't on the UI thread)

我建议使这一mHandler动荡和更新它时的方向变化。

I'd suggest making that mHandler volatile and updating it when the orientation changes.

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