JetPack系列之lifecycle的简单实践

前言

lifecycle 通过注解的方式,轻松监听Activity的声明周期。

开始

• 集成类库

build.gradle

implementation 'androidx.lifecycle:lifecycle-extensions:2.0.0'

• 编写注解类
  @OnLifecycleEvent注解可以监听声明周期

class MyChronmeter(context: Context?, attrs: AttributeSet?) : Chronometer(context, attrs),LifecycleObserver {

    var elapsedRealtime = 0L

    /**
     * onPause时候执行
     */
    @OnLifecycleEvent(Lifecycle.Event.ON_PAUSE)
    fun pauseMeter(){
        elapsedRealtime = SystemClock.elapsedRealtime()  - base
    }

    /**
     * onResume时执行
     */
    @OnLifecycleEvent(Lifecycle.Event.ON_RESUME)
    fun resumeMeter(){
        base = SystemClock.elapsedRealtime() - elapsedRealtime
    }
}

• 绑定Activity

class JetLifeCyclesActivity : AppCompatActivity() {
    lateinit var chronometer: MyChronmeter

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_life_cycler)
        chronometer = findViewById(R.id.meter)
        lifecycle.addObserver(chronometer)
    }
}

参考文章

• 使用生命周期感知型组件处理生命周期