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135 changes: 6 additions & 129 deletions
135
JetpackMvvm/src/main/java/me/hgj/jetpackmvvm/callback/livedata/event/EventLiveData.kt
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,134 +1,11 @@ | ||
| /* | ||
| * Copyright 2018-2019 KunMinX | ||
| * | ||
| * Licensed under the Apache License, Version 2.0 (the "License"); | ||
| * you may not use this file except in compliance with the License. | ||
| * You may obtain a copy of the License at | ||
| * | ||
| * http://www.apache.org/licenses/LICENSE-2.0 | ||
| * | ||
| * Unless required by applicable law or agreed to in writing, software | ||
| * distributed under the License is distributed on an "AS IS" BASIS, | ||
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| * See the License for the specific language governing permissions and | ||
| * limitations under the License. | ||
| */ | ||
| package me.hgj.jetpackmvvm.callback.livedata.event | ||
|
|
||
| import androidx.lifecycle.LifecycleOwner | ||
| import androidx.lifecycle.LiveData | ||
| import androidx.lifecycle.MutableLiveData | ||
| import androidx.lifecycle.Observer | ||
| import java.util.* | ||
| import com.kunminx.architecture.ui.callback.UnPeekLiveData | ||
|
|
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|
|
||
| /** | ||
| * TODO：UnPeekLiveData 的存在是为了在 "重回二级页面" 的场景下，解决 "数据倒灌" 的问题。 | ||
| * 对 "数据倒灌" 的状况不理解的小伙伴，可参考《jetpack MVVM 精讲》的解析 | ||
| * | ||
| * | ||
| * https://juejin.im/post/5dafc49b6fb9a04e17209922 | ||
| * | ||
| * | ||
| * 本类参考了官方 SingleEventLive 的非入侵设计， | ||
| * | ||
| * | ||
| * TODO：并创新性地引入了 "延迟清空消息" 的设计， | ||
| * 如此可确保： | ||
| * 1.一条消息能被多个观察者消费 | ||
| * 2.延迟期结束，不再能够收到旧消息的推送 | ||
| * 3.并且旧消息在延迟期结束时能从内存中释放，避免内存溢出等问题 | ||
| * 4.让非入侵设计成为可能，遵循开闭原则 | ||
| * 用于限制从 Activity/Fragment 推送数据，推送数据务必通过唯一可信源来分发， | ||
| * 如果这样说还不理解，详见： | ||
| * https://xiaozhuanlan.com/topic/6719328450 和 https://xiaozhuanlan.com/topic/0168753249 | ||
| * | ||
| * | ||
| * Create by KunMinX at 19/9/23 | ||
| * 最新版的发送消息LiveData使用 https://github.com/KunMinX/UnPeek-LiveData 的最新版，因为跟其他类名（UnPeekLiveData）一致 所以继承换了一个名字 | ||
| * 在Activity中observe 调用observeInActivity 在Fragment中使用调用 observeInFragment | ||
| * 具体写法请参考 https://github.com/KunMinX/UnPeek-LiveData的示例 | ||
| */ | ||
| open class EventLiveData<T> : MutableLiveData<T>() { | ||
| private var isCleaning = false | ||
| private var hasHandled = true | ||
| private var isDelaying = false | ||
| protected var DELAY_TO_CLEAR_EVENT = 1000 | ||
| private val mTimer = Timer() | ||
| private var mTask: TimerTask? = null | ||
| protected var isAllowNullValue = false | ||
| protected var isAllowToClear = true | ||
| override fun observe( | ||
| owner: LifecycleOwner, | ||
| observer: Observer<in T> | ||
| ) { | ||
| super.observe(owner, Observer { | ||
| if (isCleaning) { | ||
| hasHandled = true | ||
| isDelaying = false | ||
| isCleaning = false | ||
| return@Observer | ||
| } | ||
| if (!hasHandled) { | ||
| hasHandled = true | ||
| isDelaying = true | ||
| observer.onChanged(it) | ||
| } else if (isDelaying) { | ||
| observer.onChanged(it) | ||
| } | ||
| }) | ||
| } | ||
|
|
||
| /** | ||
| * UnPeekLiveData 主要用于表现层的 页面转场 和 页面间通信 场景下的非粘性消息分发， | ||
| * 出于生命周期安全等因素的考虑，不建议使用 observeForever 方法， | ||
| * | ||
| * | ||
| * 对于数据层的工作，如有需要，可结合实际场景使用 MutableLiveData 或 kotlin flow。 | ||
| * | ||
| * @param observer | ||
| */ | ||
| override fun observeForever(observer: Observer<in T?>) { | ||
| throw IllegalArgumentException("Do not use observeForever for communication between pages to avoid lifecycle security issues") | ||
| } | ||
|
|
||
| /** | ||
| * 重写的 setValue 方法，默认不接收 null | ||
| * 可通过 Builder 配置允许接收 | ||
| * 可通过 Builder 配置消息延时清理的时间 | ||
| * | ||
| * | ||
| * override setValue, do not receive null by default | ||
| * You can configure to allow receiving through Builder | ||
| * And also, You can configure the delay time of message clearing through Builder | ||
| * | ||
| * @param value | ||
| */ | ||
| override fun setValue(value: T?) { | ||
| if (!isCleaning && !isAllowNullValue && value == null) { | ||
| return | ||
| } | ||
| hasHandled = false | ||
| isDelaying = false | ||
| super.setValue(value) | ||
| if (mTask != null) { | ||
| mTask!!.cancel() | ||
| mTimer.purge() | ||
| } | ||
| if (value != null) { | ||
| mTask = object : TimerTask() { | ||
| override fun run() { | ||
| clear() | ||
| } | ||
| } | ||
| mTimer.schedule(mTask, DELAY_TO_CLEAR_EVENT.toLong()) | ||
| } | ||
| } | ||
|
|
||
| private fun clear() { | ||
| if (isAllowToClear) { | ||
| isCleaning = true | ||
| super.postValue(null) | ||
| } else { | ||
| hasHandled = true | ||
| isDelaying = false | ||
| } | ||
| } | ||
|
|
||
| } | ||
| class EventLiveData<T> : UnPeekLiveData<T>() |
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