详解Android 进程

<activity android:name=".androidsample.ActivityProgressB"
      android:process=":progressb"/>

测试结果：ActivityProgressB可以正常显示。这个其实很好理解，如果你打开系统相机页面，那个activity肯定与你的app不再一个进程，但是他可以很顺利的打开，所以可以支持。

保活

OOM_ADJ

package com.demanmath.androidms.androidsample

import android.annotation.TargetApi
import android.app.Notification
import android.app.NotificationChannel
import android.app.NotificationManager
import android.app.Service
import android.content.Context
import android.content.Intent
import android.os.Build
import android.os.Handler
import android.os.IBinder
import androidx.core.app.NotificationCompat
import com.demanmath.androidms.AppLog
import com.demanmath.androidms.R

/**
 *  @author   DemanMath
 *  @date    2020/8/14
 *
 */
class KeepLiveService:Service() {
  val NOTIFICATION_ID = 0x11
  val NOTIFICATION_CHANNEL_ID = "demanmathId"
  val channelName = "My Background Service"

  companion object {
    const val NOTIFICATION_ID = 0x11
  }
  override fun onBind(intent: Intent?): IBinder? {
    return null
  }

  override fun onCreate() {
    super.onCreate()
    if (Build.VERSION.SDK_INT < Build.VERSION_CODES.O) {
      startForeground(NOTIFICATION_ID, Notification())
    } else {
      startMyOwnForeground()
      startService(Intent(this, InnerService::class.java))
    }
  }

  @TargetApi(value = Build.VERSION_CODES.O)
  private fun startMyOwnForeground() {
    AppLog.d()
    val chan = NotificationChannel(
      NOTIFICATION_CHANNEL_ID,
      channelName,
      NotificationManager.IMPORTANCE_NONE
    )
    chan.lockscreenVisibility = Notification.VISIBILITY_PRIVATE
    val manager =
      (getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager)
    manager.createNotificationChannel(chan)
    val notificationBuilder =
      NotificationCompat.Builder(this, NOTIFICATION_CHANNEL_ID)
    val notification = notificationBuilder.setOngoing(true)
      .setSmallIcon(R.drawable.ic_launcher_background)
      .setContentTitle("App is running in background")
      .setPriority(NotificationManager.IMPORTANCE_MIN)
      .setCategory(Notification.CATEGORY_SERVICE)
      .build()
    startForeground(NOTIFICATION_ID, notification)
  }

  class InnerService : Service() {
    override fun onBind(intent: Intent): IBinder? {
      return null
    }

    override fun onCreate() {
      super.onCreate()
      //使用channeId & channelName
      //发送与KeepLiveService中ID相同的Notification，然后将其取消并取消自己的前台显示
//      val builder: Notification.Builder = Notification.Builder(this)
//      builder.setSmallIcon(R.mipmap.ic_launcher)
//      startForeground(NOTIFICATION_ID, builder.build())
      Handler().postDelayed(Runnable {
        stopForeground(true)
        val manager =
          getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
        manager.cancel(NOTIFICATION_ID)
        stopSelf()
      }, 100)
    }
  }

}

package com.demanmath.androidms.jobservice

import android.app.job.JobParameters
import android.app.job.JobService
import android.content.Intent
import android.os.Handler
import android.os.Message
import android.widget.Toast
import com.demanmath.androidms.AppLog

/**
 *  @author   DemanMath
 *  @date    2020/8/20
 *
 */
class JobDemoService:JobService() {

  override fun onCreate() {
    super.onCreate()
    AppLog.i()
  }

  override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
    AppLog.i()
    return super.onStartCommand(intent, flags, startId)
  }

  private var mHandler = object:Handler(){
    override fun handleMessage(msg: Message) {
      AppLog.i()
      Toast.makeText(
        applicationContext,
        "JobService task running", Toast.LENGTH_SHORT
      ).show()
      //请注意，我们手动调用了jobFinished方法。
      //当onStartJob返回true的时候，我们必须手动调用jobFinished方法
      //否则该应用中的其他job将不会被执行
      jobFinished(msg.obj as JobParameters, false)
    }
  }
  override fun onStartJob(params: JobParameters?): Boolean {
    AppLog.i()
    mHandler.sendMessage(Message.obtain(mHandler,1,params))
    return true
  }

  override fun onStopJob(params: JobParameters?): Boolean {
    AppLog.i()
    mHandler.removeMessages(1)
    return false
  }

}

package com.demanmath.androidms.jobservice

import android.app.job.JobInfo
import android.app.job.JobScheduler
import android.content.ComponentName
import android.content.Context
import com.demanmath.androidms.AppLog

/**
 *  @author   DemanMath
 *  @date    2020/8/20
 *
 */
class JobHelper(var context: Context) {

  lateinit var jobScheduler:JobScheduler

  fun startJob(){
    AppLog.i()
    jobScheduler = context.getSystemService(Context.JOB_SCHEDULER_SERVICE) as JobScheduler
    var builder = JobInfo.Builder(1, ComponentName(context.packageName,JobDemoService::class.java.name))

//    builder.setBackoffCriteria(1000L,JobInfo.BACKOFF_POLICY_LINEAR)
    var boolean = jobScheduler.schedule(builder.build())
    AppLog.i(boolean.toString())
  }
}