ActivityCollector类用于管理所有的Activity

object ActivityCollector {
    private val activities = ArrayList<Activity>()
    fun addActivity(activity: Activity) {
        activities.add(activity)
    }
    fun removeActivity(activity: Activity) {
        activities.remove(activity)
    }
    fun finishAll() {
        for (activity in activities) {
            if (!activity.isFinishing) {
                activity.finish()
            }
        }
        activities.clear()
    }
}

BaseActivity类作为所有Activity的父类

open class BaseActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        ActivityCollector.addActivity(this)
    }
    override fun onDestroy() {
        super.onDestroy()
        ActivityCollector.removeActivity(this)
    }
}

创建一个LoginActivity来作为登录界面

布局

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="match_parent"
        android:layout_height="60dp">
        <TextView
            android:layout_width="90dp"
            android:layout_height="wrap_content"
            android:layout_gravity="center_vertical"
            android:textSize="18sp"
            android:text="Account:" />
        <EditText
            android:id="@+id/accountEdit"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:layout_gravity="center_vertical" />
    </LinearLayout>
    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="match_parent"
        android:layout_height="60dp">
        <TextView
            android:layout_width="90dp"
            android:layout_height="wrap_content"
            android:layout_gravity="center_vertical"
            android:textSize="18sp"
            android:text="Password:" />
        <EditText
            android:id="@+id/passwordEdit"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:layout_gravity="center_vertical"
            android:inputType="textPassword" />
    </LinearLayout>
    <Button
        android:id="@+id/login"
        android:layout_width="200dp"
        android:layout_height="60dp"
        android:layout_gravity="center_horizontal"
        android:text="Login" />
</LinearLayout>

LoginActivity

class LoginActivity : AppCompatActivity() {

    private lateinit var binding: ActivityLoginBinding

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = ActivityLoginBinding.inflate(layoutInflater)
        setContentView(binding.root)

        binding.login.setOnClickListener {

            val account = binding.accountEdit.text.toString()
            val password = binding.passwordEdit.text.toString()

            if(account == "admin" && password == "123456"){
                val intent = Intent(this, MainActivity::class.java)
                startActivity(intent)
                finish()
            }else{
                Toast.makeText(this, "account or password is invaild", Toast.LENGTH_SHORT).show()
            }
        }
    }
}

在MainActivity中加入强制下线功能

布局

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >
    <Button
        android:id="@+id/forceOffline"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Send force offline broadcast" />
</LinearLayout> 

MainActivity

class MainActivity : BaseActivity() {

    private lateinit var binding: ActivityMainBinding

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = ActivityMainBinding.inflate(layoutInflater)
        setContentView(binding.root)
        binding.forceOffline.setOnClickListener {
            val intent = Intent("com.example.broadcastbestpractice.FORCE_OFFLINE")
            sendBroadcast(intent)
        }
    }
}

在BaseActivity中注册广播接收

open class BaseActivity : AppCompatActivity() {

    private lateinit var receiver: ForceOfflineReceiver

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        ActivityCollector.addActivity(this)
    }

    override fun onResume() {
        super.onResume()
        val intentFilter = IntentFilter()
        intentFilter.addAction("com.example.broadcastbestpractice.FORCE_OFFLINE")
        receiver = ForceOfflineReceiver()
        registerReceiver(receiver, intentFilter)
    }

    override fun onPause() {
        super.onPause()
        unregisterReceiver(receiver)
    }

    override fun onDestroy() {
        super.onDestroy()
        ActivityCollector.removeActivity(this)
    }

    inner class ForceOfflineReceiver: BroadcastReceiver(){

        override fun onReceive(context: Context, intent: Intent) {
            AlertDialog.Builder(context).apply{
                setTitle("Warining")
                setMessage("You are forced to be offline. Please try to login again.")
                setCancelable(false)
                setPositiveButton("OK") { _, _ ->
                    ActivityCollector.finishAll()
                    val i = Intent(context, LoginActivity::class.java)
                    context.startActivity(i)
                }
                show()
            }
        }

    }
}

将LoginActivity注册为主Activity

参考

郭霖. 《第一行代码 Android 第3版》