如何查看后台服务是否正在运行?

我想要一个切换服务状态的Android活动——它让我打开它,如果它是关闭的,如果它是关闭的。


当前回答

你可以使用Android开发者选项中的这个选项来查看你的服务是否仍然在后台运行。

1. Open Settings in your Android device.
2. Find Developer Options.
3. Find Running Services option.
4. Find your app icon.
5. You will then see all the service that belongs to your app running in the background.

其他回答

一个小补语是:

我的目标是知道一个服务是否在运行,如果它没有运行。

调用bindService或调用一个可以被服务捕获的意图不是一个好主意,因为它会在服务未运行时启动服务。

因此,正如miracle2k所建议的,最好是在服务类中有一个静态字段,以知道服务是否已经启动。

为了使它更简洁,我建议用非常非常懒惰的抓取来转换单例中的服务:也就是说,通过静态方法完全没有实例化单例实例。service/singleton的静态getInstance方法只返回已经创建的单例实例。但它并不实际启动或实例化单例本身。服务只能通过正常的服务启动方法启动。

然后,修改单例设计模式,将令人困惑的getInstance方法重命名为类似isInstanceCreated(): boolean方法的方法会更加清晰。

代码如下所示:

public class MyService extends Service
{
   private static MyService instance = null;

   public static boolean isInstanceCreated() {
      return instance != null;
   }//met

   @Override
   public void onCreate()
   {
      instance = this;
      ....
   }//met

   @Override
   public void onDestroy()
   {
      instance = null;
      ...
   }//met
}//class

这个解决方案很优雅,但只有当你可以访问服务类时才有意义,而且只适用于服务的应用程序/包旁边的类。如果你的类在服务应用程序/包之外,那么你可以用Pieter-Jan Van Robays强调的限制来查询ActivityManager。

在Kotlin课上,geekQ的反应。由于geekQ

fun isMyServiceRunning(serviceClass : Class<*> ) : Boolean{
    var manager = getSystemService(Context.ACTIVITY_SERVICE) as ActivityManager
    for (service in manager.getRunningServices(Integer.MAX_VALUE)) {
        if (serviceClass.name.equals(service.service.className)) {
            return true
        }
    }
    return false
}

调用

isMyServiceRunning(NewService::class.java)

可以有多个具有相同类名的服务。

我刚刚创建了两个应用程序。第一个应用程序的包名是com.example.mock。我在应用程序中创建了一个名为lorem的子包和一个名为Mock2Service的服务。因此它的完全限定名是com.example.mock.lorem.Mock2Service。

然后我创建了第二个应用程序和一个名为Mock2Service的服务。第二个应用程序的包名是com.example.mock.lorem。服务的完全限定名是com.example.mock.lorem。Mock2Service。

这是我的logcat输出。

03-27 12:02:19.985: D/TAG(32155): Mock-01: com.example.mock.lorem.Mock2Service
03-27 12:02:33.755: D/TAG(32277): Mock-02: com.example.mock.lorem.Mock2Service

更好的方法是比较ComponentName实例,因为ComponentName的equals()比较包名和类名。一个设备上不能安装两个包名相同的应用程序。

ComponentName的equals()方法。

@Override
public boolean equals(Object obj) {
    try {
        if (obj != null) {
            ComponentName other = (ComponentName)obj;
            // Note: no null checks, because mPackage and mClass can
            // never be null.
            return mPackage.equals(other.mPackage)
                    && mClass.equals(other.mClass);
        }
    } catch (ClassCastException e) {
    }
    return false;
}

ComponentName

简单使用绑定不创建自动查看ps和更新…

public abstract class Context {

 ... 

  /*
  * @return {true} If you have successfully bound to the service, 
  *  {false} is returned if the connection is not made 
  *  so you will not receive the service object.
  */
  public abstract boolean bindService(@RequiresPermission Intent service,
        @NonNull ServiceConnection conn, @BindServiceFlags int flags);

例子:

    Intent bindIntent = new Intent(context, Class<Service>);
    boolean bindResult = context.bindService(bindIntent, ServiceConnection, 0);

为什么不使用呢?getRunningServices ()

List<ActivityManager.RunningServiceInfo> getRunningServices (int maxNum)
Return a list of the services that are currently running.

注意:此方法仅用于调试或实现服务管理类型的用户界面。


附注:android文档具有误导性,我已经在谷歌跟踪器上打开了一个问题,以消除任何疑问:

https://issuetracker.google.com/issues/68908332

正如我们所看到的,绑定服务实际上通过ActivityManager绑定器通过服务缓存绑定器调用了一个事务-我不能跟踪哪个服务负责绑定,但正如我们所看到的,绑定的结果是:

int res = ActivityManagerNative.getDefault().bindService(...);
return res != 0;

通过装订本进行交易:

ServiceManager.getService("activity");

下一个:

  public static IBinder getService(String name) {
    try {
        IBinder service = sCache.get(name);
        if (service != null) {
            return service;
        } else {
            return getIServiceManager().getService(name);

这是在ActivityThread中通过:

 public final void bindApplication(...) {

        if (services != null) {
            // Setup the service cache in the ServiceManager
            ServiceManager.initServiceCache(services);
        }

在ActivityManagerService的method中调用:

 private final boolean attachApplicationLocked(IApplicationThread thread,
            int pid) {
    ...
    thread.bindApplication(... , getCommonServicesLocked(),...)

然后:

 private HashMap<String, IBinder> getCommonServicesLocked() {

但没有“活动”,只有窗口包和报警。

所以我们需要返回调用:

 return getIServiceManager().getService(name);

    sServiceManager = ServiceManagerNative.asInterface(BinderInternal.getContextObject());

这使呼叫通过:

    mRemote.transact(GET_SERVICE_TRANSACTION, data, reply, 0);

这就导致:

BinderInternal.getContextObject()

这是本地方法....

  /**
     * Return the global "context object" of the system.  This is usually
     * an implementation of IServiceManager, which you can use to find
     * other services.
     */
    public static final native IBinder getContextObject();

我现在没有时间去挖掘c,所以在我解析rest call之前,我暂停了我的回答。

但是检查服务是否正在运行的最好方法是创建bind(如果没有创建bind,则服务不存在)-并通过bind查询服务的状态(在其状态上使用存储的内部标志)。

更新23.06.2018

我发现这些很有趣:

/**
 * Provide a binder to an already-bound service.  This method is synchronous
 * and will not start the target service if it is not present, so it is safe
 * to call from {@link #onReceive}.
 *
 * For peekService() to return a non null {@link android.os.IBinder} interface
 * the service must have published it before. In other words some component
 * must have called {@link android.content.Context#bindService(Intent, ServiceConnection, int)} on it.
 *
 * @param myContext The Context that had been passed to {@link #onReceive(Context, Intent)}
 * @param service Identifies the already-bound service you wish to use. See
 * {@link android.content.Context#bindService(Intent, ServiceConnection, int)}
 * for more information.
 */
public IBinder peekService(Context myContext, Intent service) {
    IActivityManager am = ActivityManager.getService();
    IBinder binder = null;
    try {
        service.prepareToLeaveProcess(myContext);
        binder = am.peekService(service, service.resolveTypeIfNeeded(
                myContext.getContentResolver()), myContext.getOpPackageName());
    } catch (RemoteException e) {
    }
    return binder;
}

简而言之:)

“为已经绑定的服务提供绑定器。此方法是同步的,如果目标服务不存在,则不会启动该服务。”

(Intent service, String resolvedType) String callingPackage)抛出RemoteException;

*

public static IBinder peekService(IBinder remote, Intent service, String resolvedType)
             throws RemoteException {
    Parcel data = Parcel.obtain();
    Parcel reply = Parcel.obtain();
    data.writeInterfaceToken("android.app.IActivityManager");
    service.writeToParcel(data, 0);
    data.writeString(resolvedType);
    remote.transact(android.os.IBinder.FIRST_CALL_TRANSACTION+84, data, reply, 0);
    reply.readException();
    IBinder binder = reply.readStrongBinder();
    reply.recycle();
    data.recycle();
    return binder;
}

*

下面是一个优雅的技巧,涵盖了所有的假设。这只适用于本地服务。

    public final class AService extends Service {

        private static AService mInstance = null;

        public static boolean isServiceCreated() {
            try {
                // If instance was not cleared but the service was destroyed an Exception will be thrown
                return mInstance != null && mInstance.ping();
            } catch (NullPointerException e) {
                // destroyed/not-started
                return false;
            }
        }

        /**
         * Simply returns true. If the service is still active, this method will be accessible.
         * @return
         */
        private boolean ping() {
            return true;
        }

        @Override
        public void onCreate() {
            mInstance = this;
        }

        @Override
        public void onDestroy() {
            mInstance = null;
        }
    }

然后是:

    if(AService.isServiceCreated()){
        ...
    }else{
        startService(...);
    }