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package com.lyr.myapplication.serviceimport android.content.Intentimport android.os.Binderimport android.os.IBinderimport android.util.Logimport androidx.lifecycle.LifecycleServiceimport androidx.lifecycle.MutableLiveDataimport androidx.lifecycle.lifecycleScopeimport kotlinx.coroutines.delayimport kotlinx.coroutines.launchclass ExampleService : LifecycleService() {
        val number: MutableLiveData
   
     = MutableLiveData(0)    override fun onCreate() {
           super.onCreate()        Log.i("xxx", "开启服务")    }    override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
           lifecycleScope.launch{
               while (true) {
                   delay(1_000)//                Log.d("xx","${++number}")            }        }        return super.onStartCommand(intent, flags, startId)    }    inner class ExampleBinder : Binder() {
           val service:ExampleService = this@ExampleService    }    override fun onBind(intent: Intent): IBinder {
           super.onBind(intent)        lifecycleScope.launch{
               while (true) {
                   delay(1_000)                number.value = number.value?.plus(1)            }        }        return ExampleBinder()    }}
   

fragment 代码：

package com.lyr.myapplicationimport android.content.ComponentNameimport android.content.Contextimport android.content.Intentimport android.content.ServiceConnectionimport android.os.Bundleimport android.os.IBinderimport android.util.Logimport android.view.LayoutInflaterimport android.view.Viewimport android.view.ViewGroupimport androidx.fragment.app.Fragmentimport androidx.lifecycle.Observerimport com.lyr.myapplication.service.ExampleServiceimport kotlinx.android.synthetic.main.fragment_blank1.*// TODO: Rename parameter arguments, choose names that match// the fragment initialization parameters, e.g. ARG_ITEM_NUMBERprivate const val ARG_PARAM1 = "param1"private const val ARG_PARAM2 = "param2"/** * A simple [Fragment] subclass. * Use the [BlankFragment1.newInstance] factory method to * create an instance of this fragment. */class BlankFragment1 : Fragment() {
       // TODO: Rename and change types of parameters    override fun onCreate(savedInstanceState: Bundle?) {
           Log.i("xx", "fragment create")        super.onCreate(savedInstanceState)//        Intent//        activity?.startService(Intent(activity, ExampleService::class.java))        val intent = Intent(this.activity, ExampleService::class.java)        val serviceConnection = object : ServiceConnection {
               val at = activity as ExampleActivity            override fun onServiceDisconnected(name: ComponentName?) {
               }            override fun onServiceConnected(name: ComponentName?, service: IBinder?) {
                   (service as ExampleService.ExampleBinder).service                    .number.observe(at, Observer {
                           f1_text.text = "$it"                    })                Log.i("xxoo", "绑定服务了OK")            }        }        activity?.bindService(intent, serviceConnection, Context.BIND_AUTO_CREATE)    }    override fun onCreateView(        inflater: LayoutInflater, container: ViewGroup?,        savedInstanceState: Bundle?    ): View? {
           // Inflate the layout for this fragment        return inflater.inflate(R.layout.fragment_blank1, container, false)    }    companion object {
           /**         * Use this factory method to create a new instance of         * this fragment using the provided parameters.         *         * @param param1 Parameter 1.         * @param param2 Parameter 2.         * @return A new instance of fragment BlankFragment1.         */        // TODO: Rename and change types and number of parameters        @JvmStatic        fun newInstance(param1: String, param2: String) =            BlankFragment1().apply {
                   arguments = Bundle().apply {
                       putString(ARG_PARAM1, param1)                    putString(ARG_PARAM2, param2)                }            }    }}

多次调用startService，该Service只能被创建一次，即该Service的onCreate方法只会被调用一次。但是每次调用startService，onStartCommand方法都会被调用。Service的onStart方法在API 5时被废弃，替代它的是onStartCommand方法。

第一次执行bindService时，onCreate和onBind方法会被调用，但是多次执行bindService时，onCreate和onBind方法并不会被多次调用，即并不会多次创建服务和绑定服务。

如果要和 服务通信，需要使用 bindservice 的方法

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