App启动时间优化

1.现状分析
1.欢迎页

这个命令可以记录app的启动时间
adb shell am start -W com.rookie.demo/com.rookie.demo.LaunchActivity

Starting: Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] cmp=com.rookie.demo/.LaunchActivity }
Status: ok
LaunchState: COLD//冷启动
Activity: com.rookie.demo/.LaunchActivity
TotalTime: 3590//TotalTime表示应用的启动时间，包括创建进程，Application初始化和Activity初始化到界面显示，一般来说与ThisTime一样
WaitTime: 3593//WaitTime则表示AMS启动Activity的总耗时，一般比TotalTime大
Complete

$ adb shell am start -W com.rookie.demo/com.rookie.demo.LaunchActivity
Starting: Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] cmp=com.rookie.demo/.LaunchActivity }
Warning: Activity not started, its current task has been brought to the front
Status: ok
LaunchState: HOT//热启动
Activity: com.gtgj.view/.MainActivity
TotalTime: 207
WaitTime: 220
Complete

可以看到冷启动长达3.5s+，而对比手机淘宝

adb shell am start -W com.taobao.taobao/com.taobao.tao.TBMainActivity 
Starting: Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] cmp=com.taobao.taobao/com.taobao.tao.TBMainActivity }
Status: ok
LaunchState: COLD//冷启动
Activity: com.taobao.taobao/com.taobao.tao.TBMainActivity
TotalTime: 1492
WaitTime: 1495
Complete

adb shell am start -W com.taobao.taobao/com.taobao.tao.TBMainActivity 
Starting: Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] cmp=com.taobao.taobao/com.taobao.tao.TBMainActivity }
Warning: Activity not started, its current task has been brought to the front
Status: ok
LaunchState: HOT//热启动
Activity: com.taobao.taobao/com.taobao.tao.TBMainActivity
TotalTime: 127
WaitTime: 145
Complete

可以看到手机淘宝冷启动只有1.5s左右，