如果任何意图之前工作正常时，应用程序是在后台，这将不再是Android 8及以上的情况下。只引用意图，当app在后台时，它必须做一些处理。

必须遵循以下步骤:

Above mentioned intent should be using JobIntentService instead of IntentService. The class which extends JobIntentService should implement the - onHandleWork(@NonNull Intent intent) method and should have below the method, which will invoke the onHandleWork method: public static void enqueueWork(Context context, Intent work) { enqueueWork(context, xyz.class, 123, work); } Call enqueueWork(Context, intent) from the class where your intent is defined. Sample code: Public class A { ... ... Intent intent = new Intent(Context, B.class); //startService(intent); B.enqueueWork(Context, intent); }

下面的类以前扩展了Service类

Public Class B extends JobIntentService{
...

    public static void enqueueWork(Context context, Intent work) {
        enqueueWork(context, B.class, JobId, work);
    }

    protected void onHandleWork(@NonNull Intent intent) {
        ...
        ...
    }
}

com.android。支持:支持compat需要JobIntentService -我使用26.1.0 V。 最重要的是确保Firebase库的版本至少是10.2.1，我在10.2.0有问题——如果你有的话! 你的manifest应该具有Service类的以下权限: 服务android: name = "。B” android:出口= " false " android:许可= " android.permission.BIND_JOB_SERVICE "

希望这能有所帮助。

是的，那是因为在API 26上你不能在后台启动服务了。所以你可以在API 26之上启动ForegroundService。

你必须使用

ContextCompat.startForegroundService(...)

并在处理泄漏时发布通知。

备选方案使用JobScheduler，它可以定时在后台启动服务。

首先将类命名为Util.java

import android.app.job.JobInfo;
import android.app.job.JobScheduler;
import android.content.ComponentName;
import android.content.Context;

public class Util {
// schedule the start of the service every 10 - 30 seconds
public static void schedulerJob(Context context) {
    ComponentName serviceComponent = new ComponentName(context,TestJobService.class);
    JobInfo.Builder builder = new JobInfo.Builder(0,serviceComponent);
    builder.setMinimumLatency(1*1000);    // wait at least
    builder.setOverrideDeadline(3*1000);  //delay time
    builder.setRequiredNetworkType(JobInfo.NETWORK_TYPE_UNMETERED);  // require unmetered network
    builder.setRequiresCharging(false);  // we don't care if the device is charging or not
    builder.setRequiresDeviceIdle(true); // device should be idle
    System.out.println("(scheduler Job");

    JobScheduler jobScheduler = null;
    if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.M) {
        jobScheduler = context.getSystemService(JobScheduler.class);
    }
    jobScheduler.schedule(builder.build());
   }
  }

然后，将JobService类命名为TestJobService.java

import android.app.job.JobParameters;
import android.app.job.JobService;
import android.widget.Toast;
 
  /**
   * JobService to be scheduled by the JobScheduler.
   * start another service
   */ 
public class TestJobService extends JobService {
@Override
public boolean onStartJob(JobParameters params) {
    Util.schedulerJob(getApplicationContext()); // reschedule the job
    Toast.makeText(this, "Bg Service", Toast.LENGTH_SHORT).show();
    return true;
}

@Override
public boolean onStopJob(JobParameters params) {
    return true;
  }
 }

在名为servicerreceiver .java的BroadCast Receiver类之后

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;

 public class ServiceReceiver extends BroadcastReceiver {
 @Override
public void onReceive(Context context, Intent intent) {
    Util.schedulerJob(context);
 }
}

用服务和接收器类代码更新清单文件

<receiver android:name=".ServiceReceiver" >
        <intent-filter>
            <action android:name="android.intent.action.BOOT_COMPLETED" />
        </intent-filter>
    </receiver>
    <service
        android:name=".TestJobService"
        android:label="Word service"
        android:permission="android.permission.BIND_JOB_SERVICE" >

    </service>

将main_intent启动器留在默认创建的mainActivity.java文件中，mainActivity.java文件中的更改是

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;

public class MainActivity extends AppCompatActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Util.schedulerJob(getApplicationContext());
  }
 }

WOOAAH ! !后台服务启动时没有前台服务

[编辑]:你可以使用工作管理器的任何类型的Android后台任务。

我有办法了。对于8.0版本之前的设备，你必须使用startService()，但是对于7.0版本之后的设备，你必须使用startForgroundService()。下面是启动服务的代码示例。

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
        context.startForegroundService(new Intent(context, ServedService.class));
    } else {
        context.startService(new Intent(context, ServedService.class));
    }

在服务类中，请添加以下代码进行通知:

@Override
public void onCreate() {
    super.onCreate();
    startForeground(1,new Notification());
}

其中O为Android版本26。

如果你不想让你的服务在前台运行，而想让它在后台运行，发布Android O，你必须将服务绑定到如下连接:

Intent serviceIntent = new Intent(context, ServedService.class);
context.startService(serviceIntent);
context.bindService(serviceIntent, new ServiceConnection() {
     @Override
     public void onServiceConnected(ComponentName name, IBinder service) {
         //retrieve an instance of the service here from the IBinder returned 
         //from the onBind method to communicate with 
     }

     @Override
     public void onServiceDisconnected(ComponentName name) {
     }
}, Context.BIND_AUTO_CREATE);

允许的情况是一个临时白名单，其中后台服务的行为与Android O之前相同。

Under certain circumstances, a background app is placed on a temporary whitelist for several minutes. While an app is on the whitelist, it can launch services without limitation, and its background services are permitted to run. An app is placed on the whitelist when it handles a task that's visible to the user, such as: Handling a high-priority Firebase Cloud Messaging (FCM) message. Receiving a broadcast, such as an SMS/MMS message. Executing a PendingIntent from a notification. Starting a VpnService before the VPN app promotes itself to the foreground.

来源:https://developer.android.com/about/versions/oreo/background.html

换句话说，如果您的后台服务不符合白名单要求，您必须使用新的JobScheduler。它基本上与后台服务相同，但它周期性地被调用，而不是持续地在后台运行。

如果你使用的是IntentService，你可以改成JobIntentService。请看下面@kosev的回答。

您可以尝试此代码以避免崩溃。正如谷歌开发者在问题跟踪器中所说。

private val activityManager by lazy { getSystemService(Context.ACTIVITY_SERVICE) as ActivityManager }

//due to https://issuetracker.google.com/issues/113122354
private fun isInForegroundByImportance(): Boolean {
    val importanceState = activityManager.runningAppProcesses.find {
        it.pid == android.os.Process.myPid()
    }?.importance ?: return false
    return importanceState >= RunningAppProcessInfo.IMPORTANCE_FOREGROUND
}

和使用

override fun onResume() {
    super.onResume()
    if (Build.VERSION.SDK_INT < Build.VERSION_CODES.O || isInForegroundByImportance()) {
        val intent = Intent(this, BluetoothScannerService::class.java)
        this.startService(intent)
    }
}