Android获取网络状态

Android获取网络状态

学习自

• 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的时候，网络的状态可能会经常的变化，当用户当前没有网络的时候，我们要保证程序不崩溃，而在当用户使用流量的话，则需要确保，在进行耗流量的操作的时候，需要给予用户警告(比如看视频，播放音乐，下载等).

想要获取网络状态的话，我们需要通过 ConnectivityManager 类来实现，该类负责与 NetworkManagementService 系统服务进行交互来获取网络相关的信息。我们先来看一下官方文档是如何描述这个类的:

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

该类负责回答关于网络连接的状态的问题。 当网络连接发生改变的时候也会通知应用。

The primary responsibilities of this class are to:
该类的主要责任是:

• Monitor network connections (Wi-Fi, GPRS, UMTS, etc.)
• 监听网络连接(Wifi,GPRS,UMTS等)
• Send broadcast intents when network connectivity changes
• 当网络状态发生改变的时候，发送广播
• Attempt to "fail over" to another network when connectivity to a network is lost
• 当网络连接丢失后，尝试连接到另一个网络
• Provide an API that allows applications to query the coarse-grained or fine-grained state of the available networks
• 提供一个API来允许应用查询粗粒度或细粒度的可用网络的状态
• Provide an API that allows applications to request and select networks for their data traffic
• 提供一个API允许应用为他们的数据流量请求或者选择网络

可以通过下面的方式获取此类的实例

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

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

小贴士,请不要忘记添加 android.permission.ACCESS_NETWORK_STATE权限。

NetworkInfo

NetworkInfo 是一个描述网络连接状态的接口，我们主要通过这个类来获取网络的状态。

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

常用的功能

判断网络是否连接

/**
 * 判断网络是否可用
 * */
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
}

判断是否是移动数据

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
}

监听网络的变化

从官方文档我们可以知道，如果要想监听到网络的变化的，那么需要我们动态注册一个广播才行。

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)
    //注册一个广播
    val filter = IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION)
    this.registerReceiver(this.networkStatusChangeReceiver, filter)
}

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