allowTaskReparenting的主要作用是activity的迁移，即从一个task迁移到另一个task，这个迁移跟activity的taskAffinity有关，必须是从一个跟该activitytaskAffinity不同的task中迁移到跟它taskAffinity相同的task中，且看了下android源代码，只有在发生rese ttask时才会去使用这个标志，而我们从home上启动的程序都带了FLAG_ACTIVITY_RESET_TASK_IF_NEEDED。所以从home上启动程序会进行task reset.也就会使用到这个allowTaskReparenting。
下面来进行我们的测试：
有两个apk：
apk1中含有三个Activity:MainActivity,ActivityB,ActivityB设置了allowTaskReparenting为false.
apk2中含有一个activity:MainActivityB,MainActivityB点击的时候会启动ActivityB
首先我们启动apk2,进入MainActivityB，点击MainActivityB会进入ActivityB,我们看下 这个时候的堆栈:
ACTIVITY MANAGER ACTIVITIES (dumpsys activity activities) Main stack:TaskRecord{419878b0 #82 A com.example.testactivitylaunchflag2 U 0}Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10200000 cmp=com.example.testactivitylaunchflag2/.MainActivityB bnds=[435,1124][579,1268] }Hist #3: ActivityRecord{413c99d8 u0 com.leaves.ipanel/.ActivityB}Intent { act=com.leaves.ipanel.ActivityB cmp=com.leaves.ipanel/.ActivityB }ProcessRecord{413cba38 15618:com.leaves.ipanel/u0a10061}Hist #2: ActivityRecord{41984600 u0 com.example.testactivitylaunchflag2/.MainActivityB}Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10200000 cmp=com.example.testactivitylaunchflag2/.MainActivityB bnds=[435,1124][579,1268] }ProcessRecord{413bccb8 15600:com.example.testactivitylaunchflag2/u0a10063}TaskRecord{41350f60 #2 A com.android.launcher U 0}Intent { act=android.intent.action.MAIN cat=[android.intent.category.HOME] flg=0x10600000 cmp=com.android.launcher/com.android.launcher2.Launcher }Hist #1: ActivityRecord{41616790 u0 com.android.launcher/com.android.launcher2.Launcher}Intent { act=android.intent.action.MAIN cat=[android.intent.category.HOME] flg=0x10000000 cmp=com.android.launcher/com.android.launcher2.Launcher }ProcessRecord{41615818 628:com.android.launcher/1000}TaskRecord{413cdd58 #69 A com.android.systemui U 0}Intent { act=com.android.systemui.recent.action.TOGGLE_RECENTS flg=0x10c00000 cmp=com.android.systemui/.recent.RecentsActivity (has extras) }Hist #0: ActivityRecord{41429718 u0 com.android.systemui/.recent.RecentsActivity}Intent { act=com.android.systemui.recent.action.TOGGLE_RECENTS flg=0x10800000 cmp=com.android.systemui/.recent.RecentsActivity bnds=[550,3495][862,3690] (has extras) }ProcessRecord{414125b0 464:com.android.systemui/u0a10012} 这个时候按Home键，查看堆栈：ACTIVITY MANAGER ACTIVITIES (dumpsys activity activities) Main stack:TaskRecord{41350f60 #2 A com.android.launcher U 0}Intent { act=android.intent.action.MAIN cat=[android.intent.category.HOME] flg=0x10600000 cmp=com.android.launcher/com.android.launcher2.Launcher }Hist #3: ActivityRecord{41616790 u0 com.android.launcher/com.android.launcher2.Launcher}Intent { act=android.intent.action.MAIN cat=[android.intent.category.HOME] flg=0x10000000 cmp=com.android.launcher/com.android.launcher2.Launcher }ProcessRecord{41615818 628:com.android.launcher/1000}TaskRecord{419878b0 #82 A com.example.testactivitylaunchflag2 U 0}Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10200000 cmp=com.example.testactivitylaunchflag2/.MainActivityB bnds=[435,1124][579,1268] }Hist #2: ActivityRecord{413c99d8 u0 com.leaves.ipanel/.ActivityB}Intent { act=com.leaves.ipanel.ActivityB cmp=com.leaves.ipanel/.ActivityB }ProcessRecord{413cba38 15618:com.leaves.ipanel/u0a10061}Hist #1: ActivityRecord{41984600 u0 com.example.testactivitylaunchflag2/.MainActivityB}Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10200000 cmp=com.example.testactivitylaunchflag2/.MainActivityB bnds=[435,1124][579,1268] }ProcessRecord{413bccb8 15600:com.example.testactivitylaunchflag2/u0a10063}TaskRecord{413cdd58 #69 A com.android.systemui U 0}Intent { act=com.android.systemui.recent.action.TOGGLE_RECENTS flg=0x10c00000 cmp=com.android.systemui/.recent.RecentsActivity (has extras) }Hist #0: ActivityRecord{41429718 u0 com.android.systemui/.recent.RecentsActivity}Intent { act=com.android.systemui.recent.action.TOGGLE_RECENTS flg=0x10800000 cmp=com.android.systemui/.recent.RecentsActivity bnds=[550,3495][862,3690] (has extras) }ProcessRecord{414125b0 464:com.android.systemui/u0a10012}可以看到MainActivityB和ActivityB移动到了后台
在从Home启动apk1:
ACTIVITY MANAGER ACTIVITIES (dumpsys activity activities) Main stack:TaskRecord{423314b8 #83 A com.leaves.ipanel U 0}Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10200000 cmp=com.leaves.ipanel/.MainActivity bnds=[63,1124][207,1268] }Hist #4: ActivityRecord{4132a3d0 u0 com.leaves.ipanel/.MainActivity}Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10200000 cmp=com.leaves.ipanel/.MainActivity bnds=[63,1124][207,1268] }ProcessRecord{413cba38 15618:com.leaves.ipanel/u0a10061}TaskRecord{41350f60 #2 A com.android.launcher U 0}Intent { act=android.intent.action.MAIN cat=[android.intent.category.HOME] flg=0x10600000 cmp=com.android.launcher/com.android.launcher2.Launcher }Hist #3: ActivityRecord{41616790 u0 com.android.launcher/com.android.launcher2.Launcher}Intent { act=android.intent.action.MAIN cat=[android.intent.category.HOME] flg=0x10000000 cmp=com.android.launcher/com.android.launcher2.Launcher }ProcessRecord{41615818 628:com.android.launcher/1000}TaskRecord{419878b0 #82 A com.example.testactivitylaunchflag2 U 0}Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10200000 cmp=com.example.testactivitylaunchflag2/.MainActivityB bnds=[435,1124][579,1268] }Hist #2: ActivityRecord{413c99d8 u0 com.leaves.ipanel/.ActivityB}Intent { act=com.leaves.ipanel.ActivityB cmp=com.leaves.ipanel/.ActivityB }ProcessRecord{413cba38 15618:com.leaves.ipanel/u0a10061}Hist #1: ActivityRecord{41984600 u0 com.example.testactivitylaunchflag2/.MainActivityB}Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10200000 cmp=com.example.testactivitylaunchflag2/.MainActivityB bnds=[435,1124][579,1268] }ProcessRecord{413bccb8 15600:com.example.testactivitylaunchflag2/u0a10063}TaskRecord{413cdd58 #69 A com.android.systemui U 0}Intent { act=com.android.systemui.recent.action.TOGGLE_RECENTS flg=0x10c00000 cmp=com.android.systemui/.recent.RecentsActivity (has extras) }Hist #0: ActivityRecord{41429718 u0 com.android.systemui/.recent.RecentsActivity}Intent { act=com.android.systemui.recent.action.TOGGLE_RECENTS flg=0x10800000 cmp=com.android.systemui/.recent.RecentsActivity bnds=[550,3495][862,3690] (has extras) }ProcessRecord{414125b0 464:com.android.systemui/u0a10012} 这个时候只是简单添加了一个MainActivity.虽然从Home启动apk2的时候带有FLAG_ACTIVITY_RESET_TASK_IF_NEEDED，但在任务重置的过程中什么事也没有做。
海阔凭鱼跃，天高任鸟飞。我要加油，冲向我的理想。
