Android：双11已经过了双12都要到了，还不给你的APP加上自动换图标的功能吗？

<activity android:name=".SplashActivity">
    <intent-filter>
        <action android:name="android.intent.action.MAIN" />
        <category android:name="android.intent.category.LAUNCHER" />
    </intent-filter>
</activity>

<!--88会员节专属Activity别名-->
<activity-alias
    android:name=".SplashAliasActivity"
    android:enabled="false"
    android:icon="@mipmap/ic_launcher_88"
    android:targetActivity=".SplashActivity">
    <intent-filter>
        <action android:name="android.intent.action.MAIN" />
        <category android:name="android.intent.category.LAUNCHER" />
    </intent-filter>
</activity-alias>

<!--双11专属Activity别名-->
<activity-alias
    android:name=".SplashAlias2Activity"
    android:enabled="false"
    android:icon="@mipmap/ic_launcher_11_11"
    android:targetActivity=".SplashActivity">
    <intent-filter>
        <action android:name="android.intent.action.MAIN" />
        <category android:name="android.intent.category.LAUNCHER" />
    </intent-filter>
</activity-alias>

/**
 * 切换图标任务
 */
data class SwitchIconTask (val launcherComponentClassName: String,  // 启动器组件类名
                           val aliasComponentClassName: String,  // 别名组件类名
                           val presetTime: Long,            // 预设时间
                           val outDateTime: Long)           // 过期时间

/**
 * 启动器图标管理器
 */
object LauncherIconManager {

    /** 切换图标任务Map */
    private val taskMap: LinkedHashMap<String, SwitchIconTask> = LinkedHashMap()

    /**
     * 添加图标切换任务
     * @param newTasks 新任务，可以传多个
     */
    fun addNewTask(vararg newTasks: SwitchIconTask) {
        for (newTask in newTasks) {
            // 防止重复添加任务
            if (taskMap.containsKey(newTask.aliasComponentClassName)) return

            // 校验任务的预设时间和过期时间
            for (queuedTask in taskMap.values) {
                if (newTask.presetTime > newTask.outDateTime) throw IllegalArgumentException("非法的任务预设时间${newTask.presetTime}, 不能晚于过期时间")
                if (newTask.presetTime <= queuedTask.outDateTime) throw IllegalArgumentException("非法的任务预设时间${newTask.presetTime}, 不能早于已添加任务的过期时间")
            }

            taskMap[newTask.aliasComponentClassName] = newTask
        }
    }

    ...
}

LauncherIconManager.addNewTask(
    SwitchIconTask(
        SplashActivity::class.java.name,
        "$packageName.SplashAliasActivity",
        format.parse("2020-08-02").time,
        format.parse("2020-08-09").time
    ),
    SwitchIconTask(
        SplashActivity::class.java.name,
        "$packageName.SplashAlias2Activity",
        format.parse("2020-11-05").time,
        format.parse("2020-11-12").time
    )
)

/**
 * 应用运行状态注册器
 */
object RunningStateRegister {

    fun register(application: Application, callback: StateCallback) {
        application.registerActivityLifecycleCallbacks(object : SimpleActivityLifecycleCallbacks() {
            private var startedActivityCount = 0
            override fun onActivityStarted(activity: Activity) {
                if (startedActivityCount == 0) {
                    callback.onForeground()
                }
                startedActivityCount++
            }

            override fun onActivityStopped(activity: Activity) {
                startedActivityCount--
                if (startedActivityCount == 0) {
                    callback.onBackground()
                }
            }
        })
    }

}   

class BaseApplication : Application() {

    override fun onCreate() {
        super.onCreate()
        LauncherIconManager.register(this)
    }
}

/**
 * 启动器图标管理器
 */
object LauncherIconManager {
    ...

    /**
     * 注册以监听应用运行状态
     */
    fun register(application: Application) {
        RunningStateRegister.register(application, object: RunningStateRegister.StateCallback{
            override fun onForeground() {
            }

            override fun onBackground() {
                proofreadingInOrder(application)
            }
        })
    }

    /**
     * 依次校对预设时间
     * @param context 上下文
     */
    fun proofreadingInOrder(context: Context) {
        for (task in taskMap.values) {
            if (proofreading(context, task)) break
        }
    }

    /**
     * 校对预设时间/过期时间
     * @param context 上下文
     * @return true 已过预设时间      false 未达预设时间或已过期
     */
    private fun proofreading(context: Context, task: SwitchIconTask) =
        when {
            isPassedOutDateTime(task) -> {
                disableComponent(context, ActivityUtil.getLauncherActivityName(context)!!)
                enableComponent(context, task.launcherComponentClassName)
                false
            }
            isPassedPresetTime(task) -> {
                disableComponent(context, ActivityUtil.getLauncherActivityName(context)!!)
                enableComponent(context, task.aliasComponentClassName)
                true
            }
            else -> false
        }

    /**
     * 是否已超过预设时间
     * @param task 任务
     */
    private fun isPassedPresetTime(task: SwitchIconTask) =
        System.currentTimeMillis() > task.presetTime

    /**
     * 是否已超过过期时间
     * @param task 任务
     *
     */
    private fun isPassedOutDateTime(task: SwitchIconTask) =
        System.currentTimeMillis() > task.outDateTime

    ...
}