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 32
defaultConfig {
applicationId "com.jetpackstudy"
minSdk 21
targetSdk 32
versionCode 1
versionName "1.0"
testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
}
}
compileOptions {
sourceCompatibility JavaVersion.VERSION_1_8
targetCompatibility 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'
// room
implementation "androidx.room:room-runtime:2.4.3"
kapt "androidx.room:room-compiler:2.4.3"
// navigation
implementation "androidx.navigation:navigation-fragment-ktx:2.5.2"
implementation "androidx.navigation:navigation-ui-ktx:2.5.2"
// paging
implementation "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.lifecycle
import 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.jetpackstudy
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import com.jetpackstudy.lifecycle.MyDefaultLifecycleObserver
class 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:
以下全部代码如下:
JetPackStudyDemo全部代码,欢迎star