Android - 执行停止未恢复的活动

Question

当我将我的应用程序推到后台并执行一些其他操作（例如 whatsapp 或 sms）时，onResume 效果很好。
但我最近发现，当我的应用程序在后台打开/启动 Facebook 应用程序时，我不知道会发生什么......
但在 onResume 上，应用程序行为不端...
不要做它需要做的事情，但是当我回到主页并回来时它工作正常 请帮帮我..如何解决它？？？

带有所有消息的Logcat（不带过滤器）

10-15 12:53:59.899: I/Adreno-EGL(32033): Remote Branch: quic/LNX.LA.3.5.1_RB1.1
10-15 12:53:59.899: I/Adreno-EGL(32033): Local Patches: NONE
10-15 12:53:59.899: I/Adreno-EGL(32033): Reconstruct Branch: AU_LINUX_ANDROID_LNX.LA.3.5.1_RB1.04.04.02.048.018 + f2fd134 +  NOTHING
10-15 12:53:59.924: D/OpenGLRenderer(32033): Enabling debug mode 0
10-15 12:54:00.000: V/AlarmManager(7677): sending alarm Alarm{42cfa490 type 3 android}
10-15 12:54:00.110: I/ActivityManager(7677): Displayed uk.org.humanfocus.hfi/.EvaluateTrainingActivity: +838ms
10-15 12:54:00.114: D/WifiStateMachine(7677): handleMessage: E msg.what=151572
10-15 12:54:00.114: D/WifiStateMachine(7677): processMsg: ConnectedState
10-15 12:54:00.114: D/WifiStateMachine(7677): processMsg: L2ConnectedState
10-15 12:54:02.258: V/AlarmManager(7677): sending alarm Alarm{42ebd600 type 1 com.facebook.katana}
10-15 12:54:02.274: V/AlarmManager(7677): sending alarm Alarm{42ec0ff0 type 1 com.android.chrome}
10-15 12:54:02.428: D/hardware_info(7386): hw_info_append_hw_type : device_name = speaker
10-15 12:54:03.011: W/BroadcastQueue(7677): Permission Denial: broadcasting Intent { act=android.net.conn.INET_CONDITION_ACTION flg=0x4000010 (has extras) } from null (pid=-1, uid=-1) requires com.facebook.permission.prod.FB_APP_COMMUNICATION due to registered receiver BroadcastFilter{41fdecd0 u0 ReceiverList{42b2f608 31941 com.facebook.katana/10103/u0 remote:429a17e8}}
10-15 12:54:03.011: W/BroadcastQueue(7677): Permission Denial: broadcasting Intent { act=android.net.conn.CONNECTIVITY_CHANGE flg=0x4000010 (has extras) } from null (pid=-1, uid=-1) requires com.facebook.permission.prod.FB_APP_COMMUNICATION due to registered receiver BroadcastFilter{41fdecd0 u0 ReceiverList{42b2f608 31941 com.facebook.katana/10103/u0 remote:429a17e8}}
10-15 12:54:03.118: D/WifiStateMachine(7677): handleMessage: E msg.what=151572
10-15 12:54:03.118: D/WifiStateMachine(7677): processMsg: ConnectedState
10-15 12:54:03.118: D/WifiStateMachine(7677): processMsg: L2ConnectedState
10-15 12:54:03.140: D/WifiStateMachine(7677): handleMessage: X
10-15 12:54:03.141: D/GCoreFlp(8174): Unknown pending intent to remove.
10-15 12:54:03.145: W/fb4a(:<default>):AbstractMqttPushService(31941): Attempt to start service that is already started
10-15 12:54:03.242: D/WifiStateMachine(7677): handleMessage: E msg.what=131155
10-15 12:54:03.242: D/WifiStateMachine(7677): processMsg: ConnectedState
10-15 12:54:03.243: D/WifiStateMachine(7677): processMsg: L2ConnectedState
10-15 12:54:03.245: D/WifiStateMachine(7677): handleMessage: X
10-15 12:54:03.319: D/dalvikvm(31941): GC_CONCURRENT freed 1833K, 9% free 20190K/22072K, paused 5ms+7ms, total 86ms
10-15 12:54:03.320: D/dalvikvm(31941): WAIT_FOR_CONCURRENT_GC blocked 68ms
10-15 12:54:03.323: W/MediaPlayer-JNI(31941): MediaPlayer finalized without being released
10-15 12:54:03.452: W/BroadcastQueue(7677): Permission Denial: broadcasting Intent { act=android.net.conn.CONNECTIVITY_CHANGE flg=0x4000010 (has extras) } from null (pid=-1, uid=-1) requires com.facebook.permission.prod.FB_APP_COMMUNICATION due to registered receiver BroadcastFilter{42b51d68 u0 ReceiverList{429feb50 31941 com.facebook.katana/10103/u0 remote:41fb8788}}
10-15 12:54:03.573: W/fb4a(:<default>):JACKSON_FALLBACK(31941): Using com.fasterxml.jackson.databind.deser.std.EnumDeserializer@42914bc8 to deserialize [simple type, class com.facebook.common.util.TriState]
10-15 12:54:03.587: W/fb4a(:<default>):JACKSON_FALLBACK(31941): Using com.fasterxml.jackson.databind.deser.std.EnumDeserializer@42bb3100 to deserialize [simple type, class com.facebook.contacts.graphql.contactprofiletype.ContactProfileType]
10-15 12:54:03.957: D/dalvikvm(31941): GC_CONCURRENT freed 3400K, 15% free 20455K/23952K, paused 4ms+7ms, total 88ms
10-15 12:54:03.957: D/dalvikvm(31941): WAIT_FOR_CONCURRENT_GC blocked 75ms
10-15 12:54:04.099: W/fb4a(:<default>):JACKSON_FALLBACK(31941): Using BeanSerializer for com.facebook.katana.newbookmark.qe.NewBookmarkConfig to serialize class com.facebook.katana.newbookmark.qe.NewBookmarkConfig
10-15 12:54:04.119: D/WifiStateMachine(7677): handleMessage: E msg.what=151572
10-15 12:54:04.120: D/WifiStateMachine(7677): processMsg: ConnectedState
10-15 12:54:04.120: D/WifiStateMachine(7677): processMsg: L2ConnectedState
10-15 12:54:04.124: D/WifiStateMachine(7677): handleMessage: X
10-15 12:54:04.177: W/fb4a(:<default>):JACKSON_FALLBACK(31941): Using com.fasterxml.jackson.databind.deser.std.EnumDeserializer@42a30980 to deserialize [simple type, class com.facebook.platform.webdialogs.PlatformWebViewActionManifest$FetchState]
10-15 12:54:04.197: I/dalvikvm(31941): Could not find method com.android.internal.widget.ILockSettings$Stub.a, referenced from method com.facebook.keyguardtype.LockSettingsServiceKeyguardTypeResolver.b
10-15 12:54:04.197: W/dalvikvm(31941): VFY: unable to resolve static method 5338: Lcom/android/internal/widget/ILockSettings$Stub;.a (Landroid/os/IBinder;)Lcom/android/internal/widget/ILockSettings;
10-15 12:54:04.197: D/dalvikvm(31941): VFY: replacing opcode 0x71 at 0x0023
10-15 12:54:04.440: I/SBar.NetworkController(7758): onSignalStrengthsChanged SignalStrength: 19 0 -120 -160 -120 -1 -1 99 2147483647 2147483647 2147483647 2147483647 2147483647 gsm|lte 0 -108 -1 false 5 5 0 0 0 99 99 99 5 level=5
10-15 12:54:04.814: V/WebViewChromiumFactoryProvider(31941): Binding Chromium to main looper Looper (main, tid 1) {41f8cbd0}
10-15 12:54:04.815: I/LibraryLoader(31941): Expected native library version number "",actual native library version number ""
10-15 12:54:04.816: I/chromium(31941): [INFO:library_loader_hooks.cc(116)] Chromium logging enabled: level = 0, default verbosity = 0
10-15 12:54:04.817: I/BrowserStartupController(31941): Initializing chromium process, renderers=0
10-15 12:54:04.822: E/AudioManagerAndroid(31941): BLUETOOTH permission is missing!
10-15 12:54:04.864: W/chromium(31941): [WARNING:proxy_service.cc(890)] PAC support disabled because there is no system implementation
10-15 12:54:05.121: D/WifiStateMachine(7677): handleMessage: E msg.what=151572
10-15 12:54:05.121: D/WifiStateMachine(7677): processMsg: ConnectedState
10-15 12:54:05.122: D/WifiStateMachine(7677): processMsg: L2ConnectedState

这是 onResume()

super.onResume();

        if (backgroundThreadRunning == true) {
            backgroundThreadRunning = false;
        }

        if (Constants.isVideoEditing)
            editingProgress.setVisibility(View.VISIBLE);
        else
            editingProgress.setVisibility(View.GONE);

        if (Constants.isAudioProcessing)
            addAudioProgress.setVisibility(View.VISIBLE);
        else
            addAudioProgress.setVisibility(View.GONE);

        if (isHomeKeyPressed() && !(isRecentActivity)) {
            isRecentActivity = false;
            homeKeyPressed(false);
            AlertDialog.Builder ab = new AlertDialog.Builder(
                    CreateTrainingActivity.this);
            ab.setMessage(
                    "Due to Other Application Launches, video process will be cancelled!\nAre you sure you want to cancel?")
                    .setPositiveButton("Yes", dialogClickListener)
                    .setNegativeButton("No", dialogClickListener).show();
        }

    };

编辑：我如何解决问题

我在onResume()方法中写了这段代码

try {
    // check if any view exists on current view
    style = ((Button) findViewById(R.id.xyz_button));   
} catch (Exception e) {
    // Button was not found
    // It means, your button doesn't exist on the "current" view
    // It was freed from the memory, therefore stop of activity was performed
    // In this case I restart my app
    Intent i = new Intent();
    i.setClass(getApplicationContext(), MainActivity.class);
    i.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
    startActivity(i);
    // Show toast to the user
    Toast.makeText(getApplicationContext(), "Data lost due to excess use of other apps", Toast.LENGTH_LONG).show();
}

Answer 1

一行：您的一些活动变量似乎已从内存中释放出来，因为 Android 操作系统需要内存用于 Facebook 应用程序。

说明：当前台应用程序需要的内存超出可用内存时，Android 会从后台运行的应用程序中释放一些内存。前台任务的优先级总是高于后台应用程序。

所以，当您的应用程序在后台运行时，可能发生的事情是它的一些变量丢失了您在 onResume() 中使用的值。因此，它们持有错误的值或默认值（您可以使用 Sysout 进行检查），因为当您再次将应用程序置于前台时会重新创建它们，因此您的某些代码无法正常工作。

Answer 2

就这个问题给我 50 美分。捕获异常确实是一种可能性，但是处理活动被系统在后台获取资源的问题的正确方法是 android 中的一个常见问题，根据谷歌的解决方案是：

onPause() 是处理用户离开活动的地方。最重要的是，此时用户所做的任何更改都应提交（通常提交给持有数据的 ContentProvider）。

重点是我的。但这意味着 Android 生命周期的设计使得在正常情况下 onPause 应该被称为 Activity 或 Fragment 被发送到后台。他们在几个android documentation pages 中暗示了这一点：

当您的 Activity 进入暂停状态时，系统会在您的 Activity 上调用 onPause() 方法，该方法允许您停止在暂停时不应继续的正在进行的操作（例如视频）或保留任何应永久保存的信息保存以防用户继续离开您的应用。如果用户从暂停状态返回到您的活动，系统将恢复它并调用 onResume() 方法。

注意：当您的 Activity 收到对 onPause() 的调用时，这可能表明该 Activity 将暂停片刻，并且用户可能会将焦点返回到您的 Activity。但是，这通常是用户离开您的活动的第一个迹象。

但最有可能帮助您的资源是以下两个：

http://developer.android.com/training/basics/activity-lifecycle/stopping.html

http://developer.android.com/training/basics/activity-lifecycle/recreating.html

您丢失的资源可能会发生以下情况：

当您的活动收到对 onStop() 方法的调用时，它不再可见，并且应该释放几乎所有用户不使用时不需要的资源。一旦您的活动停止，如果需要恢复系统内存，系统可能会破坏实例。 ... 默认情况下，系统使用 Bundle 实例状态来保存有关活动布局中每个 View 对象的信息（例如输入到 EditText 对象中的文本值）。因此，如果您的活动实例被销毁并重新创建，则布局的状态将恢复到之前的状态，而您不需要任何代码。但是，您的 Activity 可能有更多您想要恢复的状态信息，例如跟踪用户在 Activity 中的进度的成员变量。

注意：为了让 Android 系统恢复 Activity 中视图的状态，每个视图必须有一个唯一的 ID，由 android:id 属性提供。

要保存有关活动状态的其他数据，您必须重写 onSaveInstanceState() 回调方法。当用户离开您的活动时，系统会调用此方法，并将 Bundle 对象传递给它，该对象将在您的活动被意外销毁时保存。如果系统以后必须重新创建活动实例，它会将相同的 Bundle 对象传递给 onRestoreInstanceState() 和 onCreate() 方法。

对此的正确解决方案是根据需要覆盖和实现 Activity / Fragment 的生命周期方法。

Google给出的两个例子：

    static final String STATE_SCORE = "playerScore";
static final String STATE_LEVEL = "playerLevel";
...

@Override
public void onSaveInstanceState(Bundle savedInstanceState) {
    // Save the user's current game state
    savedInstanceState.putInt(STATE_SCORE, mCurrentScore);
    savedInstanceState.putInt(STATE_LEVEL, mCurrentLevel);

    // Always call the superclass so it can save the view hierarchy state
    super.onSaveInstanceState(savedInstanceState);
}
Caution: Always call the superclass implementation of onSaveInstanceState() so the default implementation can save the state of the view hierarchy.

以及反向还原操作：

public void onRestoreInstanceState(Bundle savedInstanceState) {
    // Always call the superclass so it can restore the view hierarchy
    super.onRestoreInstanceState(savedInstanceState);

    // Restore state members from saved instance
    mCurrentScore = savedInstanceState.getInt(STATE_SCORE);
    mCurrentLevel = savedInstanceState.getInt(STATE_LEVEL);
}

Answer 3

希望您已经解决了这个问题，但是您的代码中存在错误，可能与此相关：

if (backgroundThreadRunning = true) {
    backgroundThreadRunning = false;
}

您正在分配而不是在“if”语句中进行比较。应该是：

if (backgroundThreadRunning == true) {
    backgroundThreadRunning = false;
}

或

if (backgroundThreadRunning) {
    backgroundThreadRunning = false;
}