Android Launcher 会onCreate 两次的理由

发布时间：2021-12-18 14:53:28 所属栏目：教程来源：互联网

导读：com.Android.server.am.ActivityStack /** * Make sure the given activity matches the current configuration. Returns * false if the activity had to be destroyed. Returns true if the * configuration is the same, or the activity will remain run

com.Android.server.am.ActivityStack
   /**
    * Make sure the given activity matches the current configuration. Returns
    * false if the activity had to be destroyed. Returns true if the
    * configuration is the same, or the activity will remain running as-is
    * for whatever reason. Ensures the HistoryRecord is updated with the
    * correct configuration and all other bookkeeping is handled.
    */
   final boolean ensureActivityConfigurationLocked(ActivityRecord r,
           int globalChanges) {
       ...
       if ((changes&(~r.info.configChanges)) != 0) {
           // Aha, the activity isn't handling the change, so DIE DIE DIE.
           r.configChangeFlags |= changes;
           r.startFreezingScreenLocked(r.app, globalChanges);
           if (r.app == null || r.app.thread == null) {
               if (DEBUG_SWITCH || DEBUG_CONFIGURATION) Slog.v(TAG,
                       "Switch is destroying non-running " + r);
               destroyActivityLocked(r, true);
           } else if (r.state == ActivityState.PAUSING) {
               // A little annoying: we are waiting for this activity to
               // finish pausing. Let's not do anything now, but just
               // flag that it needs to be restarted when done pausing.
               if (DEBUG_SWITCH || DEBUG_CONFIGURATION) Slog.v(TAG,
                       "Switch is skipping already pausing " + r);
               r.configDestroy = true;
               return true;
           } else if (r.state == ActivityState.RESUMED) {
               // Try to optimize this case: the configuration is changing
               // and we need to restart the top, resumed activity.
               // Instead of doing the normal handshaking, just say
               // "restart!".
               if (DEBUG_SWITCH || DEBUG_CONFIGURATION) Slog.v(TAG,
                       "Switch is restarting resumed " + r);

               relaunchActivityLocked(r, r.configChangeFlags, true);
               r.configChangeFlags = 0;
           } else {
               if (DEBUG_SWITCH || DEBUG_CONFIGURATION) Slog.v(TAG,
                       "Switch is restarting non-resumed " + r);
               relaunchActivityLocked(r, r.configChangeFlags, false);
               r.configChangeFlags = 0;
           }

           // All done... tell the caller we weren't able to keep this
           // activity around.
           return false;
       }
       ...
      }
注意以上代码中的第13行和第41行
Why：

        系统启动后，搜索到可用移动网络会触发 config changes : mcc | mnc

        “mcc“   The IMSI mobile country code (MCC) has changed — that is, a SIM hasbeen detected and updated the MCC.移动国家号码，由三位数字组成，每个国家都有自己独立的MCC，可以识别手机用户所属国家。
        “mnc“   The IMSI mobile network code (MNC) has changed — that is, a SIM hasbeen detected and updated the MNC.移动网号，在一个国家或者地区中，用于区分手机用户的服务商。

HowTo：

<activity android:name="Launcher" android:launchMode="singleTask" android:configChanges="mcc|mnc|keyboardHidden|orientation">

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