乐趣区

关于harmonyos:PageAbility的生命周期

作者：

jiezi

在

Page Ability生命周期

作者：韩茹

公司：程序咖（北京）科技有限公司

鸿蒙巴士专栏作家

系统管理或用户操作等行为均会引起Page实例在其生命周期的不同状态之间进行转换。Ability类提供的回调机制可能让Page及时感知外界变动，从而正确地应答状态变动（比方开释资源），这有助于晋升利用的性能和稳健性。

一、Page生命周期回调

Page Ability是次要负责页面交互的，所以Page有几个状态：可见，可交互，不可见，销毁等等。每一个状态，都有一个生命周期函数和它对应。Page生命周期的不同状态转换及其对应的回调，如下图所示所示。(图片来自官网)

  • onStart()

    当零碎首次创立Page实例时，触发该回调。对于一个Page实例，该回调在其生命周期过程中仅触发一次，Page在该逻辑后将进入INACTIVE状态。开发者必须重写该办法，并在此配置默认展现的AbilitySlice。

        @Override    
    public void onStart(Intent intent) {        
        super.onStart(intent);        
        super.setMainRoute(FooSlice.class.getName());    
    }

  • onActive()

    Page会在进入INACTIVE状态起初到前台，而后零碎调用此回调。Page在此之后进入ACTIVE状态，该状态是利用与用户交互的状态。Page将放弃在此状态，除非某类事件产生导致Page失去焦点，比方用户点击返回键或导航到其余Page。当此类事件产生时，会触发Page回到INACTIVE状态，零碎将调用onInactive()回调。尔后，Page可能从新回到ACTIVE状态，零碎将再次调用onActive()回调。因而，开发者通常须要成对实现onActive()和onInactive()，并在onActive()中获取在onInactive()中被开释的资源。

  • onInactive()

    当Page失去焦点时，零碎将调用此回调，尔后Page进入INACTIVE状态。开发者能够在此回调中实现Page失去焦点时应体现的失当行为。

  • onBackground()

    如果Page不再对用户可见，零碎将调用此回调告诉开发者用户进行相应的资源开释，尔后Page进入BACKGROUND状态。开发者应该在此回调中开释Page不可见时无用的资源，或在此回调中执行较为耗时的状态保留操作。

  • onForeground()

    处于BACKGROUND状态的Page依然驻留在内存中，当从新回到前台时（比方用户从新导航到此Page），零碎将先调用onForeground()回调告诉开发者，而后Page的生命周期状态回到INACTIVE状态。开发者该当在此回调中从新申请在onBackground()中开释的资源，最初Page的生命周期状态进一步回到ACTIVE状态，零碎将通过onActive()回调告诉开发者用户。

  • onStop()

    零碎将要销毁Page时，将会触发此回调函数，告诉用户进行系统资源的开释。销毁Page的可能起因包含以下几个方面：

    • 用户通过系统管理能力敞开指定Page，例如应用工作管理器敞开Page。
    • 用户行为触发Page的terminateAbility()办法调用，例如应用利用的退出性能。
    • 配置变更导致系统临时销毁Page并重建。
    • 零碎出于资源管理目标，主动触发对处于BACKGROUND状态Page的销毁。

示例代码：

咱们在MainAbility.java中重写以上生命周期办法，并打印HiLog日志：

package com.example.hanrupageabilitylifecycle;

import com.example.hanrupageabilitylifecycle.slice.MainAbilitySlice;
import ohos.aafwk.ability.Ability;
import ohos.aafwk.content.Intent;
import ohos.hiviewdfx.HiLog;
import ohos.hiviewdfx.HiLogLabel;
import ohos.utils.PacMap;

public class MainAbility extends Ability {

    static final HiLogLabel LABEL = new HiLogLabel(HiLog.LOG_APP, 0x00201, "TAG_ABILITY");

    // 1.当零碎首次创立 Page Ability实例时，触发该回调。将进入 INACTIVE 状态
    @Override
    public void onStart(Intent intent) {
        super.onStart(intent);
        super.setMainRoute(MainAbilitySlice.class.getName());
        HiLog.info(LABEL, "==MainAbility--->onStart()");
    }

    // 2.Page Ability 在此之后进入ACTIVE 状态，该状态是利用与用户交互的状态。
    @Override
    protected void onActive() {
        super.onActive();
        HiLog.info(LABEL, "==MainAbility--->onActive()");
    }

    // 3.当 Page Ability失去焦点时，零碎将调用此回调，尔后 Page 进入 INACTIVE 状态。
    @Override
    protected void onInactive() {
        super.onInactive();
        HiLog.info(LABEL, "==MainAbility--->onInactive()");
    }

    // 4.如果 Page Ability不再对用户可见，零碎将调用此回调告诉开发者用户进行相应的资源开释，尔后Page Ability进入 BACKGROUND 状态。
    @Override
    protected void onBackground() {
        super.onBackground();
        HiLog.info(LABEL, "==MainAbility--->onBackground()");
    }

    // 5.处于 BACKGROUND 状态的 Page Ability依然驻留在内存中，当从新回到前台时（比方用户从新导航到此 Page Ability），零碎将先调用 onForeground()回调告诉开发者，而后 Page 的生命周期状态回到 INACTIVE 状态。
    @Override
    protected void onForeground(Intent intent) {
        super.onForeground(intent);
        HiLog.info(LABEL, "==MainAbility--->onForeground()");
    }

    // 6.零碎将要销毁 Page Ability时，将会触发此回调函数，告诉用户进行系统资源的开释。
    @Override
    protected void onStop() {
        super.onStop();
        HiLog.info(LABEL, "==MainAbility--->onStop()");
    }


}

当咱们启动我的项目，我的项目默认打印HelloWorld：

终端打印：

06-25 16:46:06.165 18347-18347/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY: ==MainAbility--->onStart()
06-25 16:46:06.221 18347-18347/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY: ==MainAbility--->onActive()

到这里，咱们能够看到，当一个我的项目启动后，依据config.json配置文件，首先加载MainAbility，会先执行外面的onStart()和onActive()两个办法。

此时，而后咱们按返回键：

而后先后执行了：onInactive()–>onBackground()–>onStop()

06-25 16:50:03.231 18347-18347/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY: ==MainAbility--->onInactive()
06-25 16:50:05.153 18347-18347/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY: ==MainAbility--->onBackground()
06-25 16:50:05.166 18347-18347/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY: ==MainAbility--->onStop()

二、AbilitySlice生命周期

AbilitySlice作为Page的组成单元，其生命周期是依靠于其所属Page生命周期的。AbilitySlice和Page具备雷同的生命周期状态和同名的回调，当Page生命周期发生变化时，它的AbilitySlice也会产生雷同的生命周期变动。此外，AbilitySlice还具备独立于Page的生命周期变动，这产生在同一Page中的AbilitySlice之间导航时，此时Page的生命周期状态不会扭转。

AbilitySlice生命周期回调与Page的相应回调相似，因而不再赘述。因为AbilitySlice承载具体的页面，开发者必须重写AbilitySlice的onStart()回调，并在此办法中通过setUIContent()办法设置页面，如下所示：

    @Override    
    protected void onStart(Intent intent) {        
        super.onStart(intent);
      setUIContent(ResourceTable.Layout_main_layout);    
    }

AbilitySlice实例创立和治理通常由利用负责，零碎仅在特定状况下会创立AbilitySlice实例。例如，通过导航启动某个AbilitySlice时，是由零碎负责实例化；然而在同一个Page中不同的AbilitySlice间导航时则由利用负责实例化。

当初咱们在AbilitySlice中也重写对应的生命周期办法：

package com.example.hanrupageabilitylifecycle.slice;

import com.example.hanrupageabilitylifecycle.ResourceTable;
import ohos.aafwk.ability.AbilitySlice;
import ohos.aafwk.content.Intent;
import ohos.hiviewdfx.HiLog;
import ohos.hiviewdfx.HiLogLabel;

public class MainAbilitySlice extends AbilitySlice {
    static final HiLogLabel LABEL = new HiLogLabel(HiLog.LOG_APP, 0x00201, "TAG_ABILITY_SLICE");
    @Override
    public void onStart(Intent intent) {
        super.onStart(intent);
        super.setUIContent(ResourceTable.Layout_ability_main);
        HiLog.info(LABEL, "==MainAbilitySlice--->onStart()");
    }

    @Override
    public void onActive() {
        super.onActive();
        HiLog.info(LABEL, "==MainAbilitySlice--->onActive()");
    }

    @Override
    public void onForeground(Intent intent) {
        super.onForeground(intent);
        HiLog.info(LABEL, "==MainAbilitySlice--->onForeground()");

    }

    @Override
    protected void onInactive() {
        super.onInactive();
        HiLog.info(LABEL, "==MainAbilitySlice--->onInactive()");
    }

    @Override
    protected void onBackground() {
        super.onBackground();
        HiLog.info(LABEL, "==MainAbilitySlice--->onBackground()");
    }



    @Override
    protected void onStop() {
        super.onStop();
        HiLog.info(LABEL, "==MainAbilitySlice--->onStop()");
    }


}

启动我的项目后：

06-25 17:05:02.011 3685-3685/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY: ==MainAbility--->onStart()
06-25 17:05:02.031 3685-3685/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY_SLICE: ==MainAbilitySlice--->onStart()
06-25 17:05:02.041 3685-3685/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY: ==MainAbility--->onActive()
06-25 17:05:02.041 3685-3685/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY_SLICE: ==MainAbilitySlice--->onActive()

按下返回键：

06-25 17:08:35.311 2509-2509/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY: ==MainAbility--->onInactive()
06-25 17:08:35.311 2509-2509/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY_SLICE: ==MainAbilitySlice--->onInactive()
06-25 17:08:36.695 2509-2509/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY: ==MainAbility--->onBackground()
06-25 17:08:36.696 2509-2509/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY_SLICE: ==MainAbilitySlice--->onBackground()
06-25 17:08:36.701 2509-2509/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY: ==MainAbility--->onStop()
06-25 17:08:36.702 2509-2509/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY_SLICE: ==MainAbilitySlice--->onStop()

三、Page与AbilitySlice生命周期关联

当AbilitySlice处于前台且具备焦点时，其生命周期状态随着所属Page的生命周期状态的变动而变动。当一个Page领有多个AbilitySlice时，例如：MyAbility下有MainAbilitySlice和SecondAbilitySlice，以后MainAbilitySlice处于前台并取得焦点，并行将导航到SecondAbilitySlice，在此期间的生命周期状态变动程序为：

  1. MainAbilitySlice从ACTIVE状态变为INACTIVE状态。
  2. SecondAbilitySlice则从INITIAL状态首先变为INACTIVE状态，而后变为ACTIVE状态（假设此前SecondAbilitySlice未曾启动）。
  3. MainAbilitySlice从INACTIVE状态变为BACKGROUND状态。

对应两个slice的生命周期办法回调程序为：

MainAbilitySlice.onInactive() –> SecondAbilitySlice.onStart() –> SecondAbilitySlice.onActive() –> MainAbilitySlicee.onBackground()

在整个流程中，MyAbility始终处于ACTIVE状态。然而，当Page被零碎销毁时，其所有已实例化的AbilitySlice将联动销毁，而不仅是处于前台的AbilitySlice。

咱们通过代码来实现一下，打印察看日志。

咱们在MainAbilitySlice中增加一个按钮，点击后跳转到同一个Ability中的第二个AbilitySlice：

首先批改一下ability_main.xml：

<?xml version="1.0" encoding="utf-8"?>
<DirectionalLayout
    xmlns:ohos="http://schemas.huawei.com/res/ohos"
    ohos:height="match_parent"
    ohos:width="match_parent"
    ohos:padding="10vp"
    ohos:background_element="#22aa0000"
    ohos:orientation="vertical">

    <Text
        ohos:height="match_content"
        ohos:width="match_content"
        ohos:text="MainAbility"
        ohos:text_size="40vp"
        ohos:layout_alignment="horizontal_center"
        ohos:bottom_margin="20vp"
        />


    <Button
        ohos:id="$+id:btn1"
        ohos:height="match_content"
        ohos:width="match_content"
        ohos:text="跳转到第二个AbilitySlice"
        ohos:text_size="25fp"
        ohos:background_element="#EEEEEE"
        ohos:padding="10vp"
        />

</DirectionalLayout>

扭转一下页面色彩，以及增加一个按钮。

而后咱们再新建一个xml布局文件：ability_second.xml

<?xml version="1.0" encoding="utf-8"?>
<DirectionalLayout
    xmlns:ohos="http://schemas.huawei.com/res/ohos"
    ohos:height="match_parent"
    ohos:width="match_parent"
    ohos:alignment="center"
    ohos:background_element="#2200aa00"
    ohos:orientation="vertical">

    <Text
        ohos:id="$+id:text_helloworld"
        ohos:height="match_content"
        ohos:width="match_content"
        ohos:layout_alignment="horizontal_center"
        ohos:text="SecondAbilitySlice"
        ohos:text_size="40vp"
        />

</DirectionalLayout>

而后在slice目录下新建一个AbilitySlice：SecondAbilitySlice.java，并重写各个生命周期办法：

package com.example.hanrupageabilitylifecycle.slice;

import com.example.hanrupageabilitylifecycle.ResourceTable;
import ohos.aafwk.ability.AbilitySlice;
import ohos.aafwk.content.Intent;
import ohos.hiviewdfx.HiLog;
import ohos.hiviewdfx.HiLogLabel;

public class SecondAbilitySlice extends AbilitySlice {
    static final HiLogLabel LABEL = new HiLogLabel(HiLog.LOG_APP, 0x00201, "TAG_ABILITY_SLICE");
    @Override
    public void onStart(Intent intent) {
        super.onStart(intent);
        super.setUIContent(ResourceTable.Layout_ability_second);
        HiLog.info(LABEL, "==SecondAbilitySlice--->onStart()");
    }


    @Override
    public void onActive() {
        super.onActive();
        HiLog.info(LABEL, "==SecondAbilitySlice--->onActive()");
    }

    @Override
    public void onForeground(Intent intent) {
        super.onForeground(intent);
        HiLog.info(LABEL, "==SecondAbilitySlice--->onForeground()");

    }

    @Override
    protected void onInactive() {
        super.onInactive();
        HiLog.info(LABEL, "==SecondAbilitySlice--->onInactive()");
    }

    @Override
    protected void onBackground() {
        super.onBackground();
        HiLog.info(LABEL, "==SecondAbilitySlice--->onBackground()");
    }



    @Override
    protected void onStop() {
        super.onStop();
        HiLog.info(LABEL, "==SecondAbilitySlice--->onStop()");
    }
}

而后在MainAbilitySlice中解决按钮的点击事件：

                 // 点击按钮，跳转到SecondAbility，察看生命周期变动
        Button btn1 = (Button) findComponentById(ResourceTable.Id_btn1);
        btn1.setClickedListener(component -> present(new SecondAbilitySlice(),new Intent()));

而后我么启动程序，

察看日志：

06-25 17:23:07.026 28071-28071/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY: ==MainAbility--->onStart()
06-25 17:23:07.046 28071-28071/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY_SLICE: ==MainAbilitySlice--->onStart()
06-25 17:23:07.061 28071-28071/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY: ==MainAbility--->onActive()
06-25 17:23:07.061 28071-28071/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY_SLICE: ==MainAbilitySlice--->onActive()

而后咱们点击按钮，跳转到第二个AbilitySlice，察看日志：

06-25 17:23:42.768 28071-28071/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY_SLICE: ==MainAbilitySlice--->onInactive()
06-25 17:23:42.782 28071-28071/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY_SLICE: ==SecondAbilitySlice--->onStart()
06-25 17:23:42.783 28071-28071/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY_SLICE: ==SecondAbilitySlice--->onActive()
06-25 17:23:42.783 28071-28071/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY_SLICE: ==MainAbilitySlice--->onBackground()

而后咱们再按手机模拟器的返回键，这个时候，会退回到第一个页面，察看日志：

06-25 17:24:17.626 28071-28071/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY_SLICE: ==SecondAbilitySlice--->onInactive()
06-25 17:24:17.627 28071-28071/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY_SLICE: ==MainAbilitySlice--->onForeground()
06-25 17:24:17.629 28071-28071/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY_SLICE: ==MainAbilitySlice--->onActive()
06-25 17:24:17.629 28071-28071/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY_SLICE: ==SecondAbilitySlice--->onBackground()
06-25 17:24:17.629 28071-28071/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY_SLICE: ==SecondAbilitySlice--->onStop()

而后咱们持续按返回键，会返回到手机桌面，察看日志：

06-25 17:24:59.862 28071-28071/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY: ==MainAbility--->onInactive()
06-25 17:24:59.862 28071-28071/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY_SLICE: ==MainAbilitySlice--->onInactive()
06-25 17:25:01.214 28071-28071/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY: ==MainAbility--->onBackground()
06-25 17:25:01.214 28071-28071/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY_SLICE: ==MainAbilitySlice--->onBackground()
06-25 17:25:01.220 28071-28071/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY: ==MainAbility--->onStop()
06-25 17:25:01.221 28071-28071/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY_SLICE: ==MainAbilitySlice--->onStop()

四、Page之间切换

上面咱们来察看一下不同的Page Ability之间切换的时候，生命周期，首先新建一个Ability：OtherAbility.java：

并在外面重写生命周期的办法：

package com.example.hanrupageabilitylifecycle;

import com.example.hanrupageabilitylifecycle.slice.OtherAbilitySlice;
import com.example.hanrupageabilitylifecycle.slice.OtherAbilitySlice;
import ohos.aafwk.ability.Ability;
import ohos.aafwk.content.Intent;
import ohos.hiviewdfx.HiLog;
import ohos.hiviewdfx.HiLogLabel;

public class OtherAbility extends Ability {
  

    static final HiLogLabel LABEL = new HiLogLabel(HiLog.LOG_APP, 0x00201, "TAG_ABILITY");

    // 1.当零碎首次创立 Page Ability实例时，触发该回调。将进入 INACTIVE 状态
    @Override
    public void onStart(Intent intent) {
        super.onStart(intent);
        super.setMainRoute(OtherAbilitySlice.class.getName());
        HiLog.info(LABEL, "==OtherAbility--->onStart()");
    }

    // 2.Page Ability 在此之后进入ACTIVE 状态，该状态是利用与用户交互的状态。
    @Override
    protected void onActive() {
        super.onActive();
        HiLog.info(LABEL, "==OtherAbility--->onActive()");
    }

    // 3.当 Page Ability失去焦点时，零碎将调用此回调，尔后 Page 进入 INACTIVE 状态。
    @Override
    protected void onInactive() {
        super.onInactive();
        HiLog.info(LABEL, "==OtherAbility--->onInactive()");
    }

    // 4.如果 Page Ability不再对用户可见，零碎将调用此回调告诉开发者用户进行相应的资源开释，尔后Page Ability进入 BACKGROUND 状态。
    @Override
    protected void onBackground() {
        super.onBackground();
        HiLog.info(LABEL, "==OtherAbility--->onBackground()");
    }

    // 5.处于 BACKGROUND 状态的 Page Ability依然驻留在内存中，当从新回到前台时（比方用户从新导航到此 Page Ability），零碎将先调用 onForeground()回调告诉开发者，而后 Page 的生命周期状态回到 INACTIVE 状态。
    @Override
    protected void onForeground(Intent intent) {
        super.onForeground(intent);
        HiLog.info(LABEL, "==OtherAbility--->onForeground()");
    }

    // 6.零碎将要销毁 Page Ability时，将会触发此回调函数，告诉用户进行系统资源的开释。
    @Override
    protected void onStop() {
        super.onStop();
        HiLog.info(LABEL, "==OtherAbility--->onStop()");
    }

}

而后在生成的OtherAbilitySlice中重写生命周期办法：

package com.example.hanrupageabilitylifecycle.slice;

import com.example.hanrupageabilitylifecycle.ResourceTable;
import ohos.aafwk.ability.AbilitySlice;
import ohos.aafwk.content.Intent;
import ohos.hiviewdfx.HiLog;
import ohos.hiviewdfx.HiLogLabel;

public class OtherAbilitySlice extends AbilitySlice {
    
    static final HiLogLabel LABEL = new HiLogLabel(HiLog.LOG_APP, 0x00201, "TAG_ABILITY_SLICE");
    @Override
    public void onStart(Intent intent) {
        super.onStart(intent);
        super.setUIContent(ResourceTable.Layout_ability_other);
        HiLog.info(LABEL, "==OtherAbilitySlice--->onStart()");
    }


    @Override
    public void onActive() {
        super.onActive();
        HiLog.info(LABEL, "==OtherAbilitySlice--->onActive()");
    }

    @Override
    public void onForeground(Intent intent) {
        super.onForeground(intent);
        HiLog.info(LABEL, "==OtherAbilitySlice--->onForeground()");

    }

    @Override
    protected void onInactive() {
        super.onInactive();
        HiLog.info(LABEL, "==OtherAbilitySlice--->onInactive()");
    }

    @Override
    protected void onBackground() {
        super.onBackground();
        HiLog.info(LABEL, "==OtherAbilitySlice--->onBackground()");
    }



    @Override
    protected void onStop() {
        super.onStop();
        HiLog.info(LABEL, "==OtherAbilitySlice--->onStop()");
    }
}

批改layout下生成的ability_other.xml文件：

<?xml version="1.0" encoding="utf-8"?>
<DirectionalLayout
    xmlns:ohos="http://schemas.huawei.com/res/ohos"
    ohos:height="match_parent"
    ohos:width="match_parent"
    ohos:alignment="center"
    ohos:background_element="#220000ff"
    ohos:orientation="vertical">

    <Text
        ohos:id="$+id:text_helloworld"
        ohos:height="match_content"
        ohos:width="match_content"
        ohos:layout_alignment="horizontal_center"
        ohos:text="OtherAbility"
        ohos:text_size="40vp"
        />

</DirectionalLayout>

在ability_main.xml中增加一个按钮：

<?xml version="1.0" encoding="utf-8"?>
<DirectionalLayout
    xmlns:ohos="http://schemas.huawei.com/res/ohos"
    ohos:height="match_parent"
    ohos:width="match_parent"
    ohos:padding="10vp"
    ohos:background_element="#22aa0000"
    ohos:orientation="vertical">

        ...
    <Button
        ohos:id="$+id:btn2"
        ohos:height="match_content"
        ohos:width="match_content"
        ohos:text="跳转到另一个Ability"
        ohos:top_margin="20vp"
        ohos:text_size="25fp"
        ohos:background_element="#EEEEEE"
        ohos:padding="10vp"
        />

</DirectionalLayout>

而后在MainAbilitySlice中增加按钮的点击事件：

// 点击按钮，跳转到OtherAbility，察看生命周期
        Button btn2 = (Button) findComponentById(ResourceTable.Id_btn2);
        btn2.setClickedListener(component -> {
            //不同Page之间的导航，不能应用present()或者presentForResult()
            Intent intent1 = new Intent();
            // 通过withAbilityName()指定要跳转到Ability，然而须要同时应用withBundleName()。
            Operation operation = new Intent.OperationBuilder()
                    .withAbilityName(OtherAbility.class)
                    .withBundleName("com.example.hanrupageabilitylifecycle")
                    .build();
            intent1.setOperation(operation);
            startAbility(intent1);

        });

而后启动程序：

察看HiLog：

06-25 17:53:27.650 18293-18293/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY: ==MainAbility--->onStart()
06-25 17:53:27.675 18293-18293/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY_SLICE: ==MainAbilitySlice--->onStart()
06-25 17:53:27.700 18293-18293/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY: ==MainAbility--->onActive()
06-25 17:53:27.701 18293-18293/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY_SLICE: ==MainAbilitySlice--->onActive()

而后点击按钮，跳转到OtherAbility：

察看HiLog：

06-25 17:54:02.833 18293-18293/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY: ==MainAbility--->onInactive()
06-25 17:54:02.833 18293-18293/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY_SLICE: ==MainAbilitySlice--->onInactive()
06-25 17:54:02.928 18293-18293/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY: ==OtherAbility--->onStart()
06-25 17:54:02.936 18293-18293/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY_SLICE: ==OtherAbilitySlice--->onStart()
06-25 17:54:02.971 18293-18293/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY: ==OtherAbility--->onActive()
06-25 17:54:02.971 18293-18293/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY_SLICE: ==OtherAbilitySlice--->onActive()
06-25 17:54:03.805 18293-18293/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY: ==MainAbility--->onBackground()
06-25 17:54:03.806 18293-18293/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY_SLICE: ==MainAbilitySlice--->onBackground()

而后按手机模拟器的返回键，返回到第一个界面，察看HiLog：

06-25 17:54:52.373 18293-18293/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY: ==OtherAbility--->onInactive()
06-25 17:54:52.373 18293-18293/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY_SLICE: ==OtherAbilitySlice--->onInactive()
06-25 17:54:52.391 18293-18293/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY: ==MainAbility--->onForeground()
06-25 17:54:52.391 18293-18293/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY_SLICE: ==MainAbilitySlice--->onForeground()
06-25 17:54:52.394 18293-18293/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY: ==MainAbility--->onActive()
06-25 17:54:52.394 18293-18293/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY_SLICE: ==MainAbilitySlice--->onActive()
06-25 17:54:53.166 18293-18293/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY: ==OtherAbility--->onBackground()
06-25 17:54:53.166 18293-18293/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY_SLICE: ==OtherAbilitySlice--->onBackground()

持续按返回键，返回到桌面：


06-25 17:54:53.168 18293-18293/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY: ==OtherAbility--->onStop()
06-25 17:54:53.168 18293-18293/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY_SLICE: ==OtherAbilitySlice--->onStop()
06-25 17:55:45.057 18293-18293/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY: ==MainAbility--->onInactive()
06-25 17:55:45.057 18293-18293/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY_SLICE: ==MainAbilitySlice--->onInactive()
06-25 17:55:46.363 18293-18293/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY: ==MainAbility--->onBackground()
06-25 17:55:46.363 18293-18293/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY_SLICE: ==MainAbilitySlice--->onBackground()
06-25 17:55:46.365 18293-18293/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY: ==MainAbility--->onStop()
06-25 17:55:46.365 18293-18293/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY_SLICE: ==MainAbilitySlice--->onStop()

五、横竖屏切换

当手机横竖屏切换到时候，咱们看一下如何执行生命周期函数。

咱们打算在MainAbility设置一个成员变量num，而后设计一个按钮，每当点击按钮，num数值累加，并将数值显示到页面上。而后咱们横竖屏切换时，察看一下num数值到变动。

首先咱们批改一下MainAbility中的代码，咱们让MainAbility间接加载xml布局文件，并增加一个成员变量num：

public class MainAbility extends Ability {

    static final HiLogLabel LABEL = new HiLogLabel(HiLog.LOG_APP, 0x00201, "TAG_ABILITY");

    private int num = 100;//成员变量

    // 1.当零碎首次创立 Page Ability实例时，触发该回调。将进入 INACTIVE 状态
    @Override
    public void onStart(Intent intent) {
        super.onStart(intent);
//        super.setMainRoute(MainAbilitySlice.class.getName());
        super.setUIContent(ResourceTable.Layout_ability_main);


    }
  ...
}

而后我么批改一下ability_main：

<?xml version="1.0" encoding="utf-8"?>
<DirectionalLayout
    xmlns:ohos="http://schemas.huawei.com/res/ohos"
    ohos:height="match_parent"
    ohos:width="match_parent"
    ohos:padding="10vp"
    ohos:background_element="#22aa0000"
    ohos:orientation="vertical">

    <Text
        ohos:height="match_content"
        ohos:width="match_content"
        ohos:text="MainAbility"
        ohos:text_size="40vp"
        ohos:layout_alignment="horizontal_center"
        ohos:bottom_margin="20vp"
        />
    <Button
        ohos:id="$+id:btn3"
        ohos:height="match_content"
        ohos:width="match_content"
        ohos:text="加血加血"
        ohos:top_margin="20vp"
        ohos:text_size="25fp"
        ohos:background_element="#EEEEEE"
        ohos:padding="10vp"
        />

    <Text
        ohos:id="$+id:text_num"
        ohos:height="100vp"
        ohos:width="300vp"
        ohos:text_size="25fp"
        ohos:text="血量num：100"
        ohos:layout_alignment="horizontal_center"
        ohos:background_element="#2200ff00"
        ohos:top_margin="20vp"
        ohos:text_alignment="center"
        />



    <Button
        ohos:id="$+id:btn1"
        ohos:height="match_content"
        ohos:width="match_content"
        ohos:text="跳转到第二个AbilitySlice"
        ohos:text_size="25fp"
        ohos:background_element="#EEEEEE"
        ohos:padding="10vp"
        />
    <Button
        ohos:id="$+id:btn2"
        ohos:height="match_content"
        ohos:width="match_content"
        ohos:text="跳转到另一个Ability"
        ohos:top_margin="20vp"
        ohos:text_size="25fp"
        ohos:background_element="#EEEEEE"
        ohos:padding="10vp"
        />



</DirectionalLayout>

咱们新增一个按钮3，以及一个text。

而后咱们在MainAbility中的onStart()中解决一下按钮的点击事件：

     public void onStart(Intent intent) {
        super.onStart(intent);
        //super.setMainRoute(MainAbilitySlice.class.getName());
        super.setUIContent(ResourceTable.Layout_ability_main);

        initComponent();

        btn.setClickedListener(new Component.ClickedListener() {
            @Override
            public void onClick(Component component) {
                num++;
                textNum.setText("数值num："+num);
            }
        });

        HiLog.info(LABEL, "==MainAbility--->onStart()");
    }
        private void initComponent(){
        btn = (Button) findComponentById(ResourceTable.Id_btn3);
        textNum = (Text) findComponentById(ResourceTable.Id_text_num);
    }

而后咱们运行程序：

咱们运行后，点击按钮，将num的值累加到103，

而后切换横竖屏，发现num的值又变回100了。

察看HiLog日志：

06-25 19:57:02.990 22192-22192/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY: ==MainAbility--->onStart()
06-25 19:57:03.008 22192-22192/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY: ==MainAbility--->onActive()
06-25 19:58:15.003 22192-22192/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY: ==MainAbility--->onInactive()
06-25 19:58:15.146 22192-22192/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY: ==MainAbility--->onBackground()
06-25 19:58:15.148 22192-22192/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY: ==MainAbility--->onStop()
06-25 19:58:15.298 22192-22192/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY: ==MainAbility--->onStart()
06-25 19:58:15.382 22192-22192/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY: ==MainAbility--->onActive()

咱们发现，顺次执行了onInactive()–>onBackground()–>onStop()，而后会从新执行onStart()，onActive()办法，所以切换到横屏后，num的数值又变回了100。

那如果想保留num的数值，还要再借助于两个生命周期函数：onSaveAbilityState()和onRestoreAbilityState()：

    @Override
    public void onSaveAbilityState(PacMap outState) {
        super.onSaveAbilityState(outState);
        HiLog.info(LABEL, "==MainAbility--->onSaveAbilityState()");

        outState.putIntValue("num", num);
    }

    @Override
    public void onRestoreAbilityState(PacMap inState) {
        super.onRestoreAbilityState(inState);
        HiLog.info(LABEL, "==MainAbility--->onRestoreAbilityState()");
        num = inState.getIntValue("num");
        textNum.setText("血量num："+num);
    }

咱们从新运行一下：

咱们再来察看一下生命周期函数：

06-25 20:03:33.150 9044-9044/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY: ==MainAbility--->onStart()
06-25 20:03:33.171 9044-9044/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY: ==MainAbility--->onActive()
06-25 20:03:57.537 9044-9044/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY: ==MainAbility--->onInactive()
06-25 20:03:57.584 9044-9044/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY: ==MainAbility--->onBackground()
06-25 20:03:57.585 9044-9044/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY: ==MainAbility--->onSaveAbilityState()
06-25 20:03:57.586 9044-9044/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY: ==MainAbility--->onStop()
06-25 20:03:57.761 9044-9044/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY: ==MainAbility--->onStart()
06-25 20:03:57.764 9044-9044/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY: ==MainAbility--->onRestoreAbilityState()
06-25 20:03:57.770 9044-9044/com.example.hanrupageabilitylifecycle I 00201/TAG_ABILITY: ==MainAbility--->onActive()

最终切换到横屏之后，num也是103，完满。😄

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