如果你创建了一个后台服务来完成所有繁重的工作(tcp请求/响应，解组)，视图和活动可以被销毁并重新创建，而不会泄漏窗口或丢失数据。这允许Android推荐的行为，即在每次配置更改时销毁一个Activity。对于每个方向变化)。

它有点复杂，但它是调用服务器请求、数据预处理/后处理等的最佳方式。

您甚至可以使用您的服务将每个请求排队到服务器，因此它使处理这些事情变得简单和高效。

开发指南有一个关于服务的完整章节。

对于这些问题，我想出了一个坚如磐石的解决方案，它符合“Android方式”。我使用IntentService模式进行所有长时间运行的操作。

也就是说，我的活动广播意图，IntentService负责工作，将数据保存在DB中，然后广播粘性意图。粘性部分很重要，即使Activity在用户启动工作后暂停，并且错过了来自IntentService的实时广播，我们仍然可以响应并从调用Activity中获取数据。progressdialog可以很好地使用onSaveInstanceState()与此模式一起工作。

Basically, you need to save a flag that you have a progress dialog running in the saved instance bundle. Do not save the progress dialog object because this will leak the entire Activity. To have a persistent handle to the progress dialog, I store it as a weak reference in the application object. On orientation change or anything else that causes the Activity to pause (phone call, user hits home etc.) and then resume, I dismiss the old dialog and recreate a new dialog in the newly created Activity.

对于无限进度对话框来说，这很容易。对于进度条样式，您必须将最后一个已知的进度放在bundle中，并将您在活动中本地使用的任何信息用于跟踪进度。在恢复进度时，您将使用此信息以与之前相同的状态重新生成进度条，然后根据当前状态进行更新。

总之，将长时间运行的任务放到IntentService中，再加上明智地使用onSaveInstanceState()，可以让你有效地跟踪对话框，并在活动生命周期事件中恢复对话框。活动代码的相关部分如下。您还需要BroadcastReceiver中的逻辑来适当地处理Sticky意图，但这超出了本文的范围。

public void doSignIn(View view) {
    waiting=true;
    AppClass app=(AppClass) getApplication();
    String logingon=getString(R.string.signon);
    app.Dialog=new WeakReference<ProgressDialog>(ProgressDialog.show(AddAccount.this, "", logingon, true));
    ...
}

@Override
protected void onSaveInstanceState(Bundle saveState) {
    super.onSaveInstanceState(saveState);
    saveState.putBoolean("waiting",waiting);
}

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    if(savedInstanceState!=null) {
        restoreProgress(savedInstanceState);    
    }
    ...
}

private void restoreProgress(Bundle savedInstanceState) {
    waiting=savedInstanceState.getBoolean("waiting");
    if (waiting) {
        AppClass app=(AppClass) getApplication();
        ProgressDialog refresher=(ProgressDialog) app.Dialog.get();
        refresher.dismiss();
        String logingon=getString(R.string.signon);
        app.Dialog=new WeakReference<ProgressDialog>(ProgressDialog.show(AddAccount.this, "", logingon, true));
    }
}

我的解决方案是扩展ProgressDialog类来获得我自己的MyProgressDialog。

我重新定义了show()和dismiss()方法来在显示对话框之前锁定方向，并在对话框被解散时将其解锁。

因此，当显示对话框并且设备的方向发生变化时，屏幕的方向保持不变，直到调用dismiss()，然后屏幕方向根据传感器值/设备方向发生变化。

这是我的代码:

public class MyProgressDialog extends ProgressDialog {
    private Context mContext;

    public MyProgressDialog(Context context) {
        super(context);
        mContext = context;
    }

    public MyProgressDialog(Context context, int theme) {
        super(context, theme);
        mContext = context;
    }
    
    public void show() {
        if (mContext.getResources().getConfiguration().orientation == Configuration.ORIENTATION_PORTRAIT)
            ((Activity) mContext).setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
        else
            ((Activity) mContext).setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
        super.show();
    }
    
    public void dismiss() {
        super.dismiss();
        ((Activity) mContext).setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_SENSOR);
    }
}

我尝试执行jfelectron的解决方案，因为它是“解决这些问题的坚如磐石的解决方案，符合‘Android方式’”，但我花了一些时间来查找并整合所有提到的元素。最终得到了这个略有不同的，我认为更优雅的解决方案，完整地贴在这里。

使用从活动中触发的IntentService在单独的线程上执行长时间运行的任务。该服务向更新对话框的活动发出sticky Broadcast intent。Activity使用showDialog()， onCreateDialog()和onPrepareDialog()来消除在应用程序对象或savedInstanceState包中传递持久化数据的需要。无论应用程序如何中断，这都应该工作。

活动类:

public class TesterActivity extends Activity {
private ProgressDialog mProgressDialog;
private static final int PROGRESS_DIALOG = 0;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    Button b = (Button) this.findViewById(R.id.test_button);
    b.setOnClickListener(new OnClickListener() {
        public void onClick(View v) {
            buttonClick();
        }
    });
}

private void buttonClick(){
    clearPriorBroadcast();
    showDialog(PROGRESS_DIALOG);
    Intent svc = new Intent(this, MyService.class);
    startService(svc);
}

protected Dialog onCreateDialog(int id) {
    switch(id) {
    case PROGRESS_DIALOG:
        mProgressDialog = new ProgressDialog(TesterActivity.this);
        mProgressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
        mProgressDialog.setMax(MyService.MAX_COUNTER);
        mProgressDialog.setMessage("Processing...");
        return mProgressDialog;
    default:
        return null;
    }
}

@Override
protected void onPrepareDialog(int id, Dialog dialog) {
    switch(id) {
    case PROGRESS_DIALOG:
        // setup a broadcast receiver to receive update events from the long running process
        IntentFilter filter = new IntentFilter();
        filter.addAction(MyService.BG_PROCESS_INTENT);
        registerReceiver(new MyBroadcastReceiver(), filter);
        break;
    }
}

public class MyBroadcastReceiver extends BroadcastReceiver{
    @Override
    public void onReceive(Context context, Intent intent) {
        if (intent.hasExtra(MyService.KEY_COUNTER)){
            int count = intent.getIntExtra(MyService.KEY_COUNTER, 0);
            mProgressDialog.setProgress(count);
            if (count >= MyService.MAX_COUNTER){
                dismissDialog(PROGRESS_DIALOG);
            }
        }
    }
}

/*
 * Sticky broadcasts persist and any prior broadcast will trigger in the 
 * broadcast receiver as soon as it is registered.
 * To clear any prior broadcast this code sends a blank broadcast to clear 
 * the last sticky broadcast.
 * This broadcast has no extras it will be ignored in the broadcast receiver 
 * setup in onPrepareDialog()
 */
private void clearPriorBroadcast(){
    Intent broadcastIntent = new Intent();
    broadcastIntent.setAction(MyService.BG_PROCESS_INTENT);
    sendStickyBroadcast(broadcastIntent);
}}

IntentService经济舱:

public class MyService extends IntentService {

public static final String BG_PROCESS_INTENT = "com.mindspiker.Tester.MyService.TEST";
public static final String KEY_COUNTER = "counter";
public static final int MAX_COUNTER = 100;

public MyService() {
  super("");
}

@Override
protected void onHandleIntent(Intent intent) {
    for (int i = 0; i <= MAX_COUNTER; i++) {
        Log.e("Service Example", " " + i);
        try {
            Thread.sleep(100);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

        Intent broadcastIntent = new Intent();
        broadcastIntent.setAction(BG_PROCESS_INTENT);
        broadcastIntent.putExtra(KEY_COUNTER, i);
        sendStickyBroadcast(broadcastIntent);
    }
}}

清单文件条目:

应用前部分:

uses-permission android:name="com.mindspiker.Tester.MyService.TEST"
uses-permission android:name="android.permission.BROADCAST_STICKY"

应用程序内部部分

service android:name=".MyService"

我也遇到过同样的情况。我所做的就是在整个应用程序中只获取一个进度对话框的实例。

首先，我创建了一个DialogSingleton类来只获得一个实例(Singleton模式)

public class DialogSingleton
{
    private static Dialog dialog;

    private static final Object mLock = new Object();
    private static DialogSingleton instance;

    private DialogSingleton()
    {

    }

    public static DialogSingleton GetInstance()
    {
        synchronized (mLock)
        {
            if(instance == null)
            {
                instance = new DialogSingleton();
            }

            return instance;
        }
    }

    public void DialogShow(Context context, String title)
    {
        if(!((Activity)context).isFinishing())
        {
            dialog = new ProgressDialog(context, 2);

            dialog.setCanceledOnTouchOutside(false);

            dialog.setTitle(title);

            dialog.show();
        }
    }

    public void DialogDismiss(Context context)
    {
        if(!((Activity)context).isFinishing() && dialog.isShowing())
        {
            dialog.dismiss();
        }
    }
}

正如我在这个类中所展示的，我将进度对话框作为属性。每次我需要显示一个进度对话框时，我都会获得唯一的实例并创建一个新的ProgressDialog。

DialogSingleton.GetInstance().DialogShow(this, "My title here!");

当我完成后台任务时，我再次调用惟一实例并关闭它的对话框。

DialogSingleton.GetInstance().DialogDismiss(this);

我将后台任务状态保存在共享首选项中。当我旋转屏幕时，我问我是否有这个活动的任务运行:(onCreate)

if(Boolean.parseBoolean(preference.GetValue(IS_TASK_NAME_EXECUTED_KEY, "boolean").toString()))
{
    DialogSingleton.GetInstance().DialogShow(this, "Checking credentials!");
} // preference object gets the info from shared preferences (my own implementation to get and put data to shared preferences) and IS_TASK_NAME_EXECUTED_KEY is the key to save this flag (flag to know if this activity has a background task already running).

当我开始运行后台任务时:

preference.AddValue(IS_TASK_NAME_EXECUTED_KEY, true, "boolean");

DialogSingleton.GetInstance().DialogShow(this, "My title here!");

当我完成运行后台任务:

preference.AddValue(IS_TASK_NAME_EXECUTED_KEY, false, "boolean");

DialogSingleton.GetInstance().DialogDismiss(ActivityName.this);

我希望这能有所帮助。

我什么都试过了。花了几天时间做实验。我不想阻止活动旋转。我的设想是:

向用户显示动态信息的进度对话框。例如:“连接到服务器…”，“下载数据…”，等等。 一个线程做繁重的工作，更新对话框 在最后用结果更新UI。

The problem was, when rotating the screen, every solution on the book failed. Even with the AsyncTask class, which is the correct Android way of dealing with this situations. When rotating the screen, the current Context that the starting thread is working with, is gone, and that messes up with the dialog that is showing. The problem was always the Dialog, no matter how many tricks I added to the code (passing new contexts to running threads, retaining thread states through rotations, etc...). The code complexity at the end was always huge and there was always something that could go wrong.

对我来说唯一有效的解决方案就是“活动/对话”技巧。这很简单，很天才，而且都是旋转证明:

Instead of creating a Dialog and ask to show it, create an Activity that has been set in the manifest with android:theme="@android:style/Theme.Dialog". So, it just looks like a dialog. Replace showDialog(DIALOG_ID) with startActivityForResult(yourActivityDialog, yourCode); Use onActivityResult in the calling Activity to get the results from the executing thread (even the errors) and update the UI. On your 'ActivityDialog', use threads or AsyncTask to execute long tasks and onRetainNonConfigurationInstance to save "dialog" state when rotating the screen.

这是快速和工作良好。我仍然使用对话框的其他任务和AsyncTask的一些东西，不需要一个固定的对话框在屏幕上。但在这种情况下，我总是使用活动/对话框模式。

而且，我没有尝试它，但它甚至可以阻止活动/对话框旋转，当线程运行时，加速事情，同时允许调用活动旋转。