Android獲取網絡狀態

學習自

• https://developer.android.google.cn/reference/android/net/ConnectivityManager
• http://www.cnblogs.com/qingblog/archive/2012/07/19/2598983.html

Overview

在做Android app的時候，網絡的狀態可能會經常的變化，當用戶當前沒有網絡的時候，我們要保證程序不崩潰，而在當用戶使用流量的話，則需要確保，在進行耗流量的操作的時候，需要給予用戶警告(比如看視頻，播放音樂，下載等).

想要獲取網絡狀態的話，我們需要通過 ConnectivityManager

Class that answers queries about the state of network connectivity. It also notifies applications when network connectivity changes.

該類負責回答關於網絡連接的狀態的問題。 當網絡連接發生改變的時候也會通知應用。

The primary responsibilities of this class are to:

• Monitor network connections (Wi-Fi, GPRS, UMTS, etc.)
• 監聽網絡連接(Wifi,GPRS,UMTS等)
• Send broadcast intents when network connectivity changes
• 當網絡狀態發生改變的時候，發送廣播
• Attempt to "fail over" to another network when connectivity to a network is lost
• 當網絡連接丟失後，嘗試連接到另一個網絡
• Provide an API that allows applications to query the coarse-grained or fine-grained state of the available networks
• 提供一個API來允許應用查詢粗粒度或細粒度的可用網絡的狀態
• Provide an API that allows applications to request and select networks for their data traffic
• 提供一個API允許應用為他們的數據流量請求或者選擇網絡

可以通過下面的方式獲取此類的實例

val connectivityManager: ConnectivityManager =
        context.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager

val connectivityManager: ConnectivityManager =
        context.getSystemService(ConnectivityManager::class.java) as ConnectivityManager

小貼士,請不要忘記添加 android.permission.ACCESS_NETWORK_STATE權限。

NetworkInfo

NetworkInfo 是一個描述網絡連接狀態的接口，我們主要通過這個類來獲取網絡的狀態。

val connectivityManager: ConnectivityManager =
        context.getSystemService(ConnectivityManager::class.java) as ConnectivityManager
val networkInfo = connectivityManager.activeNetworkInfo

常用的功能

判斷網絡是否連接

/**
 * 判斷網絡是否可用
 * */
fun isAvailable(context: Context): Boolean {
    val connectivityManager: ConnectivityManager =
            context.getSystemService(ConnectivityManager::class.java) as ConnectivityManager
    val networkInfo = connectivityManager.activeNetworkInfo
    if (networkInfo != null) {
        return networkInfo.isAvailable
    }
    return false
}

判斷是否是移動數據

fun isMobile(context: Context): Boolean {
    val connectivityManager: ConnectivityManager =
            context.getSystemService(ConnectivityManager::class.java) as ConnectivityManager
    val networkInfo = connectivityManager.activeNetworkInfo
    if (networkInfo != null) {
        return networkInfo.type == ConnectivityManager.TYPE_MOBILE
    }
    return false
}

監聽網絡的變化

從官方文檔我們可以知道，如果要想監聽到網絡的變化的，那麽需要我們動態註冊一個廣播才行。

val networkStatusChangeReceiver = object : BroadcastReceiver() {
    @SuppressLint("ServiceCast")
    override fun onReceive(context: Context?, intent: Intent?) {
        val connectivityManager: ConnectivityManager =
                context!!.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
        val networkInfo = connectivityManager.activeNetworkInfo
        if (networkInfo != null && networkInfo.isAvailable) {
            tvNetworkStatus.text = "Current Network Status: Available"
        } else {
            tvNetworkStatus.text = "Current Network Status: unavailable"
        }
    }
}

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)
    //註冊一個廣播
    val filter = IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION)
    this.registerReceiver(this.networkStatusChangeReceiver, filter)
}

override fun onDestroy() {
    this.unregisterReceiver(this.networkStatusChangeReceiver)
    super.onDestroy()
}

Android獲取網絡狀態