android之taskAffinity+allowTaskReparenting

taskAffinity：指定activity的宿主对象(task)。

可以指定activity自身所需要进入的task的实例对象，如果未指定，默认使用application中的taskAffinity(默认为包名)，注意设置taskAffinity设置的String需要带前缀.，taskAffinity=".youname"。否则可能会报错INSTALL_PARSE_FAILED_MANIFEST_MALFORMED。

在这个文档里面其实讲了很多：http://developer.android.com/guide/topics/manifest/activity-element.html

这里给演示一些实例，以及解决一些疑问。

实验一：启动两个应用的launchmodetest1、launchmodetest2，launchmodetest1.MainActivity保留在默认task(launchmodetest1)中，launchmodetest2.MainActivity保留在默认task(launchmodetest2)中，而launchmodetest1.OtherActivity1+launchmodetest2.OtherActivity1保留在task(launchmodetest)中。

可以指定activity自身所需要进入的task的实例对象，如果未指定，默认包名。注意设置taskAffinity设置的String需要带前缀.，taskAffinity=".youname"。否则会报错INSTALL_PARSE_FAILED_MANIFEST_MALFORMED。

前期准备，打日志相关。 

 1     //<uses-permission android:name="android.permission.GET_TASKS"/>
 2     private final String TAG = getClass().getName();
 3     @Override
 4     protected void onResume() {
 5         new Handler().postDelayed(new Runnable() {
 6             @Override
 7             public void run() {
 8                 ActivityManager manager = (ActivityManager) getSystemService(ACTIVITY_SERVICE);
 9                 List<RunningTaskInfo> runningTaskInfos = manager.getRunningTasks(1);
10                 if(null != runningTaskInfos){
11                     RunningTaskInfo info = runningTaskInfos.get(0);
12                     Log.e(TAG, "task id:"+info.id+" base:"+info.baseActivity.toString());
13                     Log.e(TAG, "task id:"+info.id+" top:"+info.topActivity.toString());
14                 }
15             }
16         }, 500);
17         super.onResume();
18     }

project：com.example.launchmodetest1/com.example.launchmodetest2。

activities：com.example.launchmodetest1.MainActivity/com.example.launchmodetest2.MainActivity

MainActivity：taskAffinity=".launchmodetest"。

project运行com.example.launchmodetest1，然后home：

01-08 22:26:43.915: E/com.example.launchmodetest1.MainActivity(27622): task id:302 base:ComponentInfo{com.example.launchmodetest1/com.example.launchmodetest1.MainActivity}
01-08 22:26:43.915: E/com.example.launchmodetest1.MainActivity(27622): task id:302 top:ComponentInfo{com.example.launchmodetest1/com.example.launchmodetest1.MainActivity}

project运行com.example.launchmodetest2：

01-08 22:27:11.695: E/com.example.launchmodetest2.MainActivity(27810): task id:302 base:ComponentInfo{com.example.launchmodetest1/com.example.launchmodetest1.MainActivity}
01-08 22:27:11.695: E/com.example.launchmodetest2.MainActivity(27810): task id:302 top:ComponentInfo{com.example.launchmodetest2/com.example.launchmodetest2.MainActivity}

OK，launchmodetest2进入launchmodetest1栈中，但是关闭应用后重新再启动时，启动的都是launchmodetest1，结果和之前不一样。环境不是很纯粹，adb启动activity会带参数Intent.FLAG_ACTIVITY_NEW_TASK，导致结果有出入。

新增activities：com.example.launchmodetest1.OtherActivity1/com.example.launchmodetest2.OtherActivity1，MainActivity启动OtherActivity1，OtherActivity1：taskAffinity=".launchmodetest"。

使用startActivity(new Intent("com.example.launchmodetest1.OtherActivity1")，startActivity(new Intent("com.example.launchmodetest1.OtherActivity1")，测试不通过。

启动：startActivity(new Intent("com.example.launchmodetest1.OtherActivity1").setFlags(Intent.FLAG_ACTIVITY_NEW_TASK))，startActivity(new Intent("com.example.launchmodetest1.OtherActivity1").setFlags(Intent.FLAG_ACTIVITY_NEW_TASK))。

01-08 23:13:43.295: E/com.example.launchmodetest1.MainActivity(1495): task id:338 base:ComponentInfo{com.example.launchmodetest1/com.example.launchmodetest1.MainActivity}
01-08 23:13:43.295: E/com.example.launchmodetest1.MainActivity(1495): task id:338 top:ComponentInfo{com.example.launchmodetest1/com.example.launchmodetest1.MainActivity}
01-08 23:13:44.795: E/com.example.launchmodetest1.OtherActivity1(1495): task id:341 base:ComponentInfo{com.example.launchmodetest1/com.example.launchmodetest1.OtherActivity1}
01-08 23:13:44.795: E/com.example.launchmodetest1.OtherActivity1(1495): task id:341 top:ComponentInfo{com.example.launchmodetest1/com.example.launchmodetest1.OtherActivity1}
01-08 23:13:50.485: E/com.example.launchmodetest2.MainActivity(1328): task id:342 base:ComponentInfo{com.example.launchmodetest2/com.example.launchmodetest2.MainActivity}
01-08 23:13:50.485: E/com.example.launchmodetest2.MainActivity(1328): task id:342 top:ComponentInfo{com.example.launchmodetest2/com.example.launchmodetest2.MainActivity}
01-08 23:13:51.895: E/com.example.launchmodetest2.OtherActivity1(1328): task id:341 base:ComponentInfo{com.example.launchmodetest1/com.example.launchmodetest1.OtherActivity1}
01-08 23:13:51.895: E/com.example.launchmodetest2.OtherActivity1(1328): task id:341 top:ComponentInfo{com.example.launchmodetest2/com.example.launchmodetest2.OtherActivity1}

测试通过，launchmodetest1.MainActivity->launchmodetest1.OtherActivity1->home->launchmodetest2.MainActivity->launchmodetest2.OtherActivity1

连续返回：

01-08 23:14:42.405: E/com.example.launchmodetest1.OtherActivity1(1495): task id:341 base:ComponentInfo{com.example.launchmodetest1/com.example.launchmodetest1.OtherActivity1}
01-08 23:14:42.405: E/com.example.launchmodetest1.OtherActivity1(1495): task id:341 top:ComponentInfo{com.example.launchmodetest1/com.example.launchmodetest1.OtherActivity1}
01-08 23:14:44.015: E/com.example.launchmodetest2.MainActivity(1328): task id:342 base:ComponentInfo{com.example.launchmodetest2/com.example.launchmodetest2.MainActivity}
01-08 23:14:44.015: E/com.example.launchmodetest2.MainActivity(1328): task id:342 top:ComponentInfo{com.example.launchmodetest2/com.example.launchmodetest2.MainActivity}

结果：launchmodetest2.OtherActivity1->launchmodetest1.OtherActivity1->launchmodetest2.MainActivity，符合预期。

解释：launchmodetest1.MainActivity(task(launchmodetest1))->launchmodetest1.OtherActivity1(task(launchmodetest))->home((task(launcher)))->launchmodetest2.MainActivity((task(launchmodetest2)))->launchmodetest2.OtherActivity1((task(launchmodetest)))，启动结束时，涉及4个task，task(launchmodetest1)在task(launcher)之下，task(launcher)之上有两个task，task(launchmodetest2)+task(launchmodetest)，当前显示的是task(launchmodetest).aunchmodetest2.OtherActivity1，点击返回，回到task(launchmodetest).launchmodetest1.OtherActivity1，再返回，回到task(launchmodetest2)，显示task(launchmodetest2).launchmodetest2.MainActivity，再返回，回到task(launcher)。

总结：taskAffinity+Intent.FLAG_ACTIVITY_NEW_TASK在第一次选择task时可以宿主到taskAffinity设置的task里。

allowTaskReparenting：允许activity的重新宿主对象(task)。

如果一个应用的activity1启动另一个应用的activity2(standard)且未使用Intent.FLAG_ACTIVITY_NEW_TASK，那么activity2有可能在该task里面完成自己的生命周期，回不到它原taskAffinity指定的task里面。

实验一：activity重新宿主

project：com.example.launchmodetest1/com.example.launchmodetest2。

activities：com.example.launchmodetest1.MainActivity、com.example.launchmodetest1.OtherActivity1/com.example.launchmodetest2.MainActivity

OtherActivity1：allowTaskReparenting="true"。

启动launchmodetest2.MainActivity->launchmodetest1.OtherActivity1

01-09 01:40:15.595: E/com.example.launchmodetest2.MainActivity(13210): task id:429 base:ComponentInfo{com.example.launchmodetest2/com.example.launchmodetest2.MainActivity}
01-09 01:40:15.595: E/com.example.launchmodetest2.MainActivity(13210): task id:429 top:ComponentInfo{com.example.launchmodetest2/com.example.launchmodetest2.MainActivity}
01-09 01:40:19.205: E/com.example.launchmodetest1.OtherActivity1(13080): task id:429 base:ComponentInfo{com.example.launchmodetest2/com.example.launchmodetest2.MainActivity}
01-09 01:40:19.205: E/com.example.launchmodetest1.OtherActivity1(13080): task id:429 top:ComponentInfo{com.example.launchmodetest1/com.example.launchmodetest1.OtherActivity1}

home->launchmodetest2

01-09 01:42:15.055: E/com.example.launchmodetest2.MainActivity(13210): task id:429 base:ComponentInfo{com.example.launchmodetest2/com.example.launchmodetest2.MainActivity}
01-09 01:42:15.055: E/com.example.launchmodetest2.MainActivity(13210): task id:429 top:ComponentInfo{com.example.launchmodetest2/com.example.launchmodetest2.MainActivity}

home->launchmodetest1

01-09 01:42:42.515: E/com.example.launchmodetest1.OtherActivity1(13080): task id:431 base:ComponentInfo{com.example.launchmodetest1/com.example.launchmodetest1.OtherActivity1}
01-09 01:42:42.515: E/com.example.launchmodetest1.OtherActivity1(13080): task id:431 top:ComponentInfo{com.example.launchmodetest1/com.example.launchmodetest1.OtherActivity1}

解释：launchmodetest2.MainActivity(task(launchmodetest2))->launchmodetest1.OtherActivity1(task(launchmodetest2))->launcher(task(launcher))->launchmodetest2(task(launchmodetest2))->launcher->launchmodetest1(task(launchmodetest1))此时launchmodetest1.OtherActivity1的task从(task(launchmodetest2))->(task(launchmodetest1))。