文章目录

• • 1. LifeCycle(生命周期管理)简介
  • 2. 使用
  • 3. 效果如下

1. LifeCycle(生命周期管理)简介

lifeCycle主要是用来解耦的，LifeCycle可以帮助开发者创建可感知生命周期的组件。这样，组件便能够在其内部管理自己的生命周期，从而降低模块间的耦合度，并降低内存泄漏发生的可能性。LifeCycle不只对Activity/Fragment有用，在Service和Application中也能大显身手。其作用如下：

• 使用Lifecycle解耦页面与组件
• 使用LifecycleService解耦Service与组件
• 使用ProcessLifecycleOwner监听应用程序周期

如果没有Lifecycle，则需要在onResume(), onStop()等生命周期函数中去写，项目一旦大了，就难以维护。

2. 使用

Step1: 添加依赖

plugins {id 'com.android.application'id 'org.jetbrains.kotlin.android'id 'kotlin-kapt'
}android {compileSdk 32defaultConfig {applicationId "com.jetpackstudy"minSdk 21targetSdk 32versionCode 1versionName "1.0"testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"}buildTypes {release {minifyEnabled falseproguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'}}compileOptions {sourceCompatibility JavaVersion.VERSION_1_8targetCompatibility JavaVersion.VERSION_1_8}kotlinOptions {jvmTarget = '1.8'}
}dependencies {implementation 'androidx.core:core-ktx:1.7.0'implementation 'androidx.appcompat:appcompat:1.3.0'implementation 'com.google.android.material:material:1.4.0'implementation 'androidx.constraintlayout:constraintlayout:2.0.4'testImplementation 'junit:junit:4.13.2'androidTestImplementation 'androidx.test.ext:junit:1.1.3'androidTestImplementation 'androidx.test.espresso:espresso-core:3.4.0'// lifecycle监听整个应用程序的生命周期implementation 'androidx.lifecycle:lifecycle-process:2.5.1'implementation 'androidx.lifecycle:lifecycle-livedata-ktx:2.3.1'implementation 'androidx.lifecycle:lifecycle-viewmodel-ktx:2.3.1'// viewModel的获取implementation 'androidx.fragment:fragment-ktx:1.5.2'// roomimplementation "androidx.room:room-runtime:2.4.3"kapt "androidx.room:room-compiler:2.4.3"// navigationimplementation "androidx.navigation:navigation-fragment-ktx:2.5.2"implementation "androidx.navigation:navigation-ui-ktx:2.5.2"// pagingimplementation "androidx.paging:paging-runtime:3.1.1"
}

添加里面对应的依赖即可

Step2： 实现DefaultLifecycleObserver接口

package com.jetpackstudy.lifecycleimport android.util.Log
import androidx.lifecycle.DefaultLifecycleObserver
import androidx.lifecycle.LifecycleOwner/***  author  : ctb*  date    : 2022/10/29 22:18*  desc    : 监听生命周期*/private const val TAG = "MyDefaultLifecycleObser"
class MyDefaultLifecycleObserver: DefaultLifecycleObserver{override fun onCreate(owner: LifecycleOwner) {super.onCreate(owner)// 可以在这些地方添加业务逻辑Log.d(TAG, "onCreate: ")}override fun onStart(owner: LifecycleOwner) {super.onStart(owner)Log.d(TAG, "onStart: ")}override fun onResume(owner: LifecycleOwner) {super.onResume(owner)Log.d(TAG, "onResume: ")}override fun onPause(owner: LifecycleOwner) {super.onPause(owner)Log.d(TAG, "onPause: ")}override fun onStop(owner: LifecycleOwner) {super.onStop(owner)Log.d(TAG, "onStop: ")}override fun onDestroy(owner: LifecycleOwner) {super.onDestroy(owner)Log.d(TAG, "onDestroy: ")}}

Step3: 在Activity中添加观察者：

package com.jetpackstudyimport androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import com.jetpackstudy.lifecycle.MyDefaultLifecycleObserverclass MainActivity : AppCompatActivity() {override fun onCreate(savedInstanceState: Bundle?) {super.onCreate(savedInstanceState)setContentView(R.layout.activity_main)lifecycle.addObserver(MyDefaultLifecycleObserver())		// 仅需添加一行代码即可完成}
}

3. 效果如下

运行后的效果如下：