Service 详解

Local Service

Start and stop

Manifest

val intent = Intent(this, MyService::class.java)
startService(intent)
stopService(intent)

Bind and unbind

MyService

class MyService : Service() {

    class LocalBinder : Binder() {
        fun getTime(): Long {
            return System.currentTimeMillis()
        }
    }
    private var mLocalBinder = LocalBinder()

    override fun onBind(intent: Intent): IBinder? {
        log("onBind")
        return mLocalBinder
    }
}

private val mServiceConnection = object : ServiceConnection {
    override fun onServiceConnected(name: ComponentName, service: IBinder) {
        mLocalService = service as MyService.LocalBinder
    }

    override fun onServiceDisconnected(name: ComponentName) {
    }
}
val intent = Intent(this, MyService::class.java)
bindService(intent)
unbindService(intent)

start,stop,bind,unbind 混合调用

• stopService只会让Service停止，unbindService只会让Service和context解除关联。
  
• 一个service必须要在既没有和任何context关联又处在停止状态的时候才会被销毁。

start,stop,bind,unbind 各类调用场景日志

--- start service
onCreate
onStart
--- start service
onStart
--- stop service
onDestroy

--- bind service
onCreate
onBind
--- bind service
--- unBind service
onUnbind
onDestroy

--- start service
onCreate
onStart
--- bind service
onBind
--- stop service
--- unBind service
onUnbind
onDestroy

--- start service
onCreate
onStart
--- bind service
onBind
--- stop service
--- unBind service
onUnbind
onDestroy

前台Service

调用service的startForeground即可

@Override
    public void onCreate() {
        super.onCreate();
        startForeground(1, new Notification(R.mipmap.ic_launcher, "title", System.currentTimeMillis()));
    }

Remote Service

Removete service 在另一个进程中运行。不能直接bind，要bind要AIDL

RemoteService 声明

外部APP启动remote service

Intent intent = new Intent("com.example.servicetest.MyAIDLService");
bindService(intent, connection, BIND_AUTO_CREATE);

AIDL 使用步骤

1. 在项目中新建aild文件（例如 IMServiceAidl.aidl)，在文件中写接口函数，sync工程，IDE会自动生成aidl对应的文件(IMServiceAidl.java)，文件中有。

编写的 IMyServiceAidl.aidl

package com.example.demo0109.service;

interface IMyServiceAidl {
    long getTime();
}

image

生成类 IMyServiceAidl.java 的结构

image

2. bind service

    private ServiceConnection mServiceConnection = new ServiceConnection() {
        @Override
        public void onServiceConnected(ComponentName name, IBinder service) {
            mMyServiceAidl = IMyServiceAidl.Stub.asInterface(service);
        }

        @Override
        public void onServiceDisconnected(ComponentName name) {
            mMyServiceAidl = null;
        }
    };

bind service的时候，remote service 与 local service 的区别

// common service
mMyService = (MyService) iBinder;
// remote service
mMyServiceAidl = IMyServiceAidl.Stub.asInterface(iBinder);

附录：完整代码

MainActivity.kt

class MainActivity : AppCompatActivity() {

    private var mRemoteBinder: IMyServiceAidl? = null
    private var mLocalService: MyService.LocalBinder? = null
    private val mServiceConnection = object : ServiceConnection {
        override fun onServiceConnected(name: ComponentName, service: IBinder) {
            mLocalService = service as MyService.LocalBinder
//            mRemoteBinder = IMyServiceAidl.Stub.asInterface(service)
        }

        override fun onServiceDisconnected(name: ComponentName) {
        }
    }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val intent = Intent(this, MyService::class.java)
        bt_start_service.setOnClickListener {
            log("--- start service")
            startService(intent)
        }
        bt_stop_service.setOnClickListener {
            log("--- stop service")
            stopService(intent)
        }
        bt_bind_service.setOnClickListener {
            log("--- bind service")
            bindService(intent, mServiceConnection, Service.BIND_AUTO_CREATE)
        }
        bt_unbind_service.setOnClickListener {
            log("--- unBind service")
            unbindService(mServiceConnection)
        }
    }

    private fun log(s: String) {
        Log.d("MyService", s)
    }
}

MyService.kt

class MyService : Service() {

    class LocalBinder : Binder() {
        fun getTime(): Long {
            return System.currentTimeMillis()
        }
    }

    private var mLocalBinder = LocalBinder()
    private var mRemoteBinder: IMyServiceAidl.Stub = object : IMyServiceAidl.Stub() {
        @Throws(RemoteException::class)
        override fun getTime(): Long {
            return System.currentTimeMillis()
        }
    }

    override fun onBind(intent: Intent): IBinder? {
        log("onBind")
        return mLocalBinder
//        return mRemoteBinder
    }

    override fun onUnbind(intent: Intent): Boolean {
        log("onUnbind")
        return super.onUnbind(intent)
    }

    override fun onCreate() {
        super.onCreate()
        startForeground(1, Notification(R.mipmap.ic_launcher, "title", System.currentTimeMillis()))
        log("onCreate")
    }

    override fun onStartCommand(intent: Intent, flags: Int, startId: Int): Int {
        log("onStart")
        return super.onStartCommand(intent, flags, startId)
    }

    override fun onDestroy() {
        super.onDestroy()
        log("onDestroy")
    }

    private fun log(s: String) {
        Log.d(javaClass.simpleName, s)
    }
}

IMyServiceAidl.aidl

package com.example.demo0109.service;
interface IMyServiceAidl {
    long getTime();
}

Manifest.xml

参考：

Android Service完全解析，关于服务你所需知道的一切(上)

Android Service完全解析，关于服务你所需知道的一切(上)