前言

在APP的開(kāi)發(fā)中，獲取到網(wǎng)絡(luò)的鏈接狀態(tài)是一個(gè)經(jīng)常使用到的方法聂薪。除了可以使用ping指令來(lái)判斷當(dāng)前的網(wǎng)絡(luò)狀況之外家乘，還可以直接通過(guò)ConnectivityManager來(lái)對(duì)網(wǎng)絡(luò)狀態(tài)進(jìn)行判斷。

一藏澳、網(wǎng)絡(luò)判斷舊方法（deprecated）

權(quán)限申請(qǐng)

如果要獲取網(wǎng)絡(luò)信息仁锯，首先是需要申請(qǐng)網(wǎng)絡(luò)權(quán)限：

<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

判斷網(wǎng)絡(luò)

使用ConnectivityManager可以十分方便的直接判斷網(wǎng)絡(luò)，調(diào)用方法如下：

    //判斷網(wǎng)絡(luò)是否連接
    fun isNetworkConnected(context: Context?): Boolean {
        if (context != null) {
            val mConnectivityManager = context
                .getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
            val mNetworkInfo = mConnectivityManager.activeNetworkInfo
            if (mNetworkInfo != null) {
                return mNetworkInfo.isAvailable
            }
        }
        return false
    }
        //判斷WiFi是否連接
    fun isWifiConnected(context: Context?): Boolean {
        if (context != null) {
            val mConnectivityManager = context
                .getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
            val mWiFiNetworkInfo = mConnectivityManager
                .getNetworkInfo(ConnectivityManager.TYPE_WIFI)
            if (mWiFiNetworkInfo != null) {
                return mWiFiNetworkInfo.isAvailable
            }
        }
        return false
    }

    //判斷移動(dòng)網(wǎng)絡(luò)是否連接
    fun isMobileConnected(context: Context?): Boolean {
        if (context != null) {
            val mConnectivityManager = context
                .getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
            val mMobileNetworkInfo = mConnectivityManager
                .getNetworkInfo(ConnectivityManager.TYPE_MOBILE)
            if (mMobileNetworkInfo != null) {
                return mMobileNetworkInfo.isAvailable
            }
        }
        return false
    }

    //獲取連接網(wǎng)絡(luò)的網(wǎng)絡(luò)信息
    fun getConnectedType(context: Context?): Int {
        if (context != null) {
            val mConnectivityManager = context
                .getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
            val mNetworkInfo = mConnectivityManager.activeNetworkInfo
            if (mNetworkInfo != null && mNetworkInfo.isAvailable) {
                return mNetworkInfo.type
            }
        }
        return -1
    }

但是在完成代碼之后卻發(fā)現(xiàn)有些方法已經(jīng)被標(biāo)記為deprecated了翔悠，如isAvailable()和getActiveNetworkInfo()方法业崖。查看代碼注釋野芒，其中提示我們應(yīng)該使用ConnectivityManager.NetworkCallback去監(jiān)聽(tīng)網(wǎng)絡(luò)連接變化，并使用registerNetworkCallback去注冊(cè)監(jiān)聽(tīng)双炕，內(nèi)容如下：

     * @deprecated Apps should instead use the
     *             {@link android.net.ConnectivityManager.NetworkCallback} API to
     *             learn about connectivity changes.
     *             {@link ConnectivityManager#registerDefaultNetworkCallback} and
     *             {@link ConnectivityManager#registerNetworkCallback}. These will
     *             give a more accurate picture of the connectivity state of
     *             the device and let apps react more easily and quickly to changes.

接下來(lái)狞悲，我們對(duì)此網(wǎng)絡(luò)監(jiān)聽(tīng)api進(jìn)行簡(jiǎn)單說(shuō)明。

二妇斤、網(wǎng)絡(luò)監(jiān)聽(tīng)

ConnectivityManager.NetworkCallback是一個(gè)抽象類摇锋，具有如下幾個(gè)方法：

其中最為常用的方法為onAvailable,onLost,onCapabilitiesChanged方法。

我們定義一個(gè)繼承自ConnectivityManager.NetworkCallback的子類：NetUtil站超，示例代碼如下：

package com.example.demowork1.util

import android.content.Context
import android.net.ConnectivityManager
import android.net.LinkProperties
import android.net.Network
import android.net.NetworkCapabilities


class NetUtil: ConnectivityManager.NetworkCallback() {

    //網(wǎng)絡(luò)連接成功
    override fun onAvailable(network: Network) {
        LogUtil.instance.d("網(wǎng)絡(luò)連接成功")
        super.onAvailable(network)
    }

    //網(wǎng)絡(luò)已斷開(kāi)連接
    override fun onLost(network: Network) {
        LogUtil.instance.d("網(wǎng)絡(luò)已斷開(kāi)連接")
        super.onLost(network)
    }

    override fun onLosing(network: Network, maxMsToLive: Int) {
        LogUtil.instance.d("網(wǎng)絡(luò)正在斷開(kāi)連接")
        super.onLosing(network, maxMsToLive)
    }

    //無(wú)網(wǎng)絡(luò)
    override fun onUnavailable() {
        LogUtil.instance.d("網(wǎng)絡(luò)連接超時(shí)或者網(wǎng)絡(luò)連接不可達(dá)")
        super.onUnavailable()
    }

    //當(dāng)網(wǎng)絡(luò)狀態(tài)修改（網(wǎng)絡(luò)依然可用）時(shí)調(diào)用
    override fun onCapabilitiesChanged(network: Network, networkCapabilities: NetworkCapabilities) {
        super.onCapabilitiesChanged(network, networkCapabilities)
        LogUtil.instance.d( "net status change! 網(wǎng)絡(luò)連接改變")
    }

    //當(dāng)訪問(wèn)的網(wǎng)絡(luò)被阻塞或者解除阻塞時(shí)調(diào)用
    override fun onBlockedStatusChanged(network: Network, blocked: Boolean) {
        super.onBlockedStatusChanged(network, blocked)
    }

    //當(dāng)網(wǎng)絡(luò)連接屬性發(fā)生變化時(shí)調(diào)用
    override fun onLinkPropertiesChanged(network: Network, linkProperties: LinkProperties) {
        super.onLinkPropertiesChanged(network, linkProperties)
    }
    ...
}

onCapabilitiesChanged(Network network, NetworkCapabilities networkCapabilities)是我們較為常用的網(wǎng)絡(luò)狀態(tài)發(fā)生變化時(shí)的監(jiān)聽(tīng)荸恕，其中的參數(shù)networkCapabilities包含有一些我們常用的api ，其中保羅有兩個(gè)重要方法死相，如下：

1. hasCapability
2. hasTransport

hasCapability可以判斷網(wǎng)絡(luò)是否連接融求，有多個(gè)參數(shù)（參數(shù)可以查看接口NetCapability），其中常用參數(shù)如下：

hasTransport可以判斷網(wǎng)絡(luò)的類型媳纬，同樣有多個(gè)參數(shù)（參數(shù)可以查看接口Transport）双肤，其中常用的參數(shù)如下：

具體的調(diào)用示例如下：

    //當(dāng)網(wǎng)絡(luò)狀態(tài)修改（網(wǎng)絡(luò)依然可用）時(shí)調(diào)用
    override fun onCapabilitiesChanged(network: Network, networkCapabilities: NetworkCapabilities) {
        super.onCapabilitiesChanged(network, networkCapabilities)
        LogUtil.instance.d( "net status change! 網(wǎng)絡(luò)連接改變")
        // 表明此網(wǎng)絡(luò)連接成功驗(yàn)證
        if (networkCapabilities.hasCapability(NetworkCapabilities.NET_CAPABILITY_VALIDATED)) {
            if (networkCapabilities.hasTransport(NetworkCapabilities.TRANSPORT_WIFI)) {
                // 使用WI-FI
                LogUtil.instance.d("當(dāng)前在使用WiFi上網(wǎng)")
            } else if (networkCapabilities.hasTransport(NetworkCapabilities.TRANSPORT_CELLULAR)) {
                // 使用數(shù)據(jù)網(wǎng)絡(luò)
                LogUtil.instance.d("當(dāng)前在使用數(shù)據(jù)網(wǎng)絡(luò)上網(wǎng)")
            } else{
                LogUtil.instance.d("當(dāng)前在使用其他網(wǎng)絡(luò)")
                // 未知網(wǎng)絡(luò)，包括藍(lán)牙钮惠、VPN等
            }
        }
    }

監(jiān)聽(tīng)調(diào)用

具體的調(diào)用實(shí)現(xiàn)如下：

    private fun setNetListener() {
        var request = NetworkRequest.Builder().build()
        var connMgr = getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
        connMgr.registerNetworkCallback(request, NetUtil.instance)
    }

三茅糜、 同步網(wǎng)絡(luò)狀態(tài)獲取

需要注意的是，雖然Google提供了此Callback方法來(lái)獲取網(wǎng)絡(luò)狀態(tài)的素挽，但是此回調(diào)是異步的蔑赘，如果需要同步獲取網(wǎng)絡(luò)狀態(tài)，需要調(diào)用如下方法getNetworkCapabilities(Network network)方法來(lái)獲取當(dāng)前NetWork的連接狀態(tài)预明，示例代碼如下：

                val network = mConnectivityManager.activeNetwork ?: return false
                val status = mConnectivityManager.getNetworkCapabilities(network)
                        ?: return false
                if (status.hasCapability(NetworkCapabilities.NET_CAPABILITY_VALIDATED)) {
                    return true
                }

但是此方法是出現(xiàn)在Android M之后的SDK中缩赛，所以同步獲取網(wǎng)絡(luò)連接狀態(tài)的代碼還需要對(duì)Android的版本進(jìn)行判斷，最終代碼如下：

    /**
     * 判斷網(wǎng)絡(luò)是否連接
     */
    fun isNetworkConnected(context: Context?): Boolean {
        if (context != null) {
            val mConnectivityManager = context
                    .getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
            if (Build.VERSION.SDK_INT < Build.VERSION_CODES.M) {
                val mNetworkInfo = mConnectivityManager.activeNetworkInfo
                if (mNetworkInfo != null) {
                    return mNetworkInfo.isAvailable
                }
            } else {
                val network = mConnectivityManager.activeNetwork ?: return false
                val status = mConnectivityManager.getNetworkCapabilities(network)
                        ?: return false
                if (status.hasCapability(NetworkCapabilities.NET_CAPABILITY_VALIDATED)) {
                    return true
                }
            }
        }
        return false
    }

    /**
     * 判斷是否是WiFi連接
     */
    fun isWifiConnected(context: Context?): Boolean {
        if (context != null) {
            val mConnectivityManager = context
                    .getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
            if (Build.VERSION.SDK_INT < Build.VERSION_CODES.M) {
                val mWiFiNetworkInfo = mConnectivityManager
                        .getNetworkInfo(ConnectivityManager.TYPE_WIFI)
                if (mWiFiNetworkInfo != null) {
                    return mWiFiNetworkInfo.isAvailable
                }
            } else {
                val network = mConnectivityManager.activeNetwork ?: return false
                val status = mConnectivityManager.getNetworkCapabilities(network)
                        ?: return false
                if (status.hasTransport(NetworkCapabilities.TRANSPORT_WIFI)) {
                    return true
                }
            }
        }
        return false
    }

    /**
     * 判斷是否是數(shù)據(jù)網(wǎng)絡(luò)連接
     */
    fun isMobileConnected(context: Context?): Boolean {
        if (context != null) {
            val mConnectivityManager = context
                    .getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
            if (Build.VERSION.SDK_INT < Build.VERSION_CODES.M) {
                val mMobileNetworkInfo = mConnectivityManager
                        .getNetworkInfo(ConnectivityManager.TYPE_MOBILE)
                if (mMobileNetworkInfo != null) {
                    return mMobileNetworkInfo.isAvailable
                }
            } else {
                val network = mConnectivityManager.activeNetwork ?: return false
                val status = mConnectivityManager.getNetworkCapabilities(network)
                        ?: return false
                status.transportInfo
                if (status.hasTransport(NetworkCapabilities.TRANSPORT_CELLULAR)) {
                    return true
                }
            }
        }
        return false
    }

總結(jié)

本文主要是對(duì)于獲取網(wǎng)絡(luò)狀態(tài)以及網(wǎng)絡(luò)監(jiān)聽(tīng)進(jìn)行說(shuō)明撰糠，需要注意的是對(duì)于同步和異步的區(qū)分酥馍。

參考文章

google官方文檔