Android Flow监听网络状态

Posted 2022-08-16 安果移不动

这些个api要用到api24

你可以往下写兼容代码 也可以先不去适配使用minSdk这样

minSdk 24

 

 

用到了一个接口

package com.example.prettynumber

import kotlinx.coroutines.flow.Flow
//监听状态。并返回流
interface ConnectivityObserver 
    fun observer(): Flow<Status>
    enum class Status
        Available,Unavailable,Losing,Lost
    

实现

package com.example.prettynumber

import android.content.Context
import android.net.ConnectivityManager
import android.net.Network
import android.os.Build
import androidx.annotation.RequiresApi
import kotlinx.coroutines.channels.awaitClose
import kotlinx.coroutines.flow.Flow
import kotlinx.coroutines.flow.callbackFlow
import kotlinx.coroutines.flow.distinctUntilChanged
import kotlinx.coroutines.launch

class NetworkConnectivityObserver(private val context: Context) : ConnectivityObserver 
    private val connectivityManager =
        context.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager

    @RequiresApi(Build.VERSION_CODES.N)
    override fun observer(): Flow<ConnectivityObserver.Status> 
        return callbackFlow 
            val callbacks = object : ConnectivityManager.NetworkCallback() 
                override fun onAvailable(network: Network) 
                    super.onAvailable(network)
                    launch 
                        send(ConnectivityObserver.Status.Available)
                    
                

                override fun onLosing(network: Network, maxMsToLive: Int) 
                    super.onLosing(network, maxMsToLive)
                    launch 
                        send(ConnectivityObserver.Status.Losing)
                    
                

                override fun onLost(network: Network) 
                    super.onLost(network)
                    //更新当前事件
                    launch 
                        send(ConnectivityObserver.Status.Lost)
                    
                

                override fun onUnavailable() 
                    super.onUnavailable()
                    launch 
                        send(ConnectivityObserver.Status.Unavailable)
                    
                


            
            //注册事件，需要表明 要大于24才行哦
            connectivityManager.registerDefaultNetworkCallback(callbacks)
            //解除注册事件
            awaitClose 
                connectivityManager.unregisterNetworkCallback(callbacks)
            


        
            //防止重复注册事件
            .distinctUntilChanged()
    

使用

class MainActivity : ComponentActivity() 
    private lateinit var connectivityObserver: ConnectivityObserver
    private val TAG = "MainActivity"
    override fun onCreate(savedInstanceState: Bundle?) 
        super.onCreate(savedInstanceState)
        connectivityObserver = NetworkConnectivityObserver(applicationContext)
        connectivityObserver.observer().onEach 
            Log.e(TAG, "Status is: $it")
        .launchIn(lifecycleScope)
        setContent 
            PrettyNumberTheme 

                val status by connectivityObserver.observer().collectAsState(
                    initial = ConnectivityObserver.Status.Unavailable
                )
                Box(
                    modifier = Modifier.fillMaxSize(),
                    contentAlignment = Alignment.Center
                ) 
                    Text(text = "Network status:$status")