監(jiān)聽網(wǎng)絡(luò)變化在開發(fā)中是經(jīng)常用到的，例如我們斷網(wǎng)有一些友好的提示，或者根據(jù)不同的網(wǎng)絡(luò)更改一些加載策略，例如wifi看視頻，非wifi則會有一個(gè)提示，等等情況。

在5.0以前，我們都是廣播BroadcastReceiver，注冊跟網(wǎng)絡(luò)變化相關(guān)的廣播，然后判斷是連接還是斷開，這種做法非常方便，但是隨著安卓的版本迭代，在權(quán)限上越來越謹(jǐn)慎，廣播的方式就顯得不太優(yōu)雅。

所以在安卓5.0以上終于對網(wǎng)絡(luò)的監(jiān)聽進(jìn)行了優(yōu)化，那就是通過Callback回調(diào)的方式，這種開發(fā)模式是不是很常用？例如監(jiān)聽下載進(jìn)度，我只需要三個(gè)回調(diào)：下載成功，下載失敗，下載的進(jìn)度變化，這種回調(diào)方式針對性強(qiáng)，耦合性低，非常方便。

為此我借鑒了大牛們的一些做法以及代碼，寫了一點(diǎn)東西，希望5.0之前和之后都能兼容到。

主要涉及到三個(gè)核心類：
代碼如下：
NetworkCallbackUtil.java

import android.content.Context;
import android.net.Network;
import android.net.NetworkInfo;
import android.os.Build;

/**
 * 監(jiān)聽網(wǎng)絡(luò)連接狀態(tài)
 * 主要作用類還是 NetworkCallbackImpl
 */
public class NetworkCallbackUtil {

    /**
     * 在application中調(diào)用
     */
    public static void register(Context context) {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
            NetworkCallbackImpl.getInstance().register(context);
        } else {
            NetworkChangBroadcast.getInstance().register(context);
        }
    }

    public static void addNetworkCallback(Object tag, ConnectivityChangeCallback call) {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
            NetworkCallbackImpl.getInstance().addNetworkCallback(tag, call);
        } else {
            NetworkChangBroadcast.getInstance().addNetworkCallback(tag, call);
        }
    }

    public static void removeNetworkCallback(Object tag) {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
            NetworkCallbackImpl.getInstance().removeNetworkCallback(tag);
        } else {
            NetworkChangBroadcast.getInstance().removeNetworkCallback(tag);
        }
    }


    /**
     * 網(wǎng)絡(luò)狀態(tài)監(jiān)聽接口
     * 可模仿ConnectivityManager.NetworkCallback的接口方法（在NetworkCallbackImpl中），目前只用到兩個(gè)
     * Network network:兼容NetworkCallbackImpl
     * NetworkInfo networkInfo:兼容NetworkChangBroadcast
     */
    public interface ConnectivityChangeCallback {
        void onAvailable(Network network, NetworkInfo networkInfo);

        void onLost(Network network, NetworkInfo networkInfo);
    }
}

NetworkCallbackImpl.java：

import android.content.Context;
import android.net.ConnectivityManager;
import android.net.LinkProperties;
import android.net.Network;
import android.net.NetworkCapabilities;
import android.net.NetworkRequest;
import android.os.Build;
import android.support.annotation.RequiresApi;

import java.util.HashMap;
import java.util.Map;

@RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
public class NetworkCallbackImpl {
    private ConnectivityManager.NetworkCallback networkCallback;
    private Map<Object, NetworkCallbackUtil.ConnectivityChangeCallback> callbackList = new HashMap<>();

    private NetworkCallbackImpl() {
        networkCallback = new ConnectivityManager.NetworkCallback() {
            /**
             * 網(wǎng)絡(luò)可用的回調(diào)
             */
            @Override
            public void onAvailable(Network network) {
                super.onAvailable(network);
//                Toast.makeText(context, "onAvailable:", Toast.LENGTH_SHORT).show();
                for (NetworkCallbackUtil.ConnectivityChangeCallback callback : callbackList.values()) {
                    callback.onAvailable(network, null);
                }
            }

            /**
             * 在網(wǎng)絡(luò)失去連接的時(shí)候回調(diào)，但是如果是一個(gè)生硬的斷開，他可能不回調(diào)
             */
            @Override
            public void onLosing(Network network, int maxMsToLive) {
                super.onLosing(network, maxMsToLive);
//        Toast.makeText(context, "onLosing", Toast.LENGTH_SHORT).show();
            }

            /**
             * 網(wǎng)絡(luò)丟失的回調(diào)
             */
            @Override
            public void onLost(Network network) {
                super.onLost(network);
//        Toast.makeText(context, "onLost", Toast.LENGTH_SHORT).show();
                for (NetworkCallbackUtil.ConnectivityChangeCallback callback : callbackList.values()) {
                    callback.onLost(network, null);
                }
            }

            /**
             * 按照官方的字面意思是，當(dāng)我們的網(wǎng)絡(luò)的某個(gè)能力發(fā)生了變化回調(diào)，那么也就是說可能會回調(diào)多次
             * <p>
             * 之后在仔細(xì)的研究
             */
            @Override
            public void onCapabilitiesChanged(Network network, NetworkCapabilities networkCapabilities) {
                super.onCapabilitiesChanged(network, networkCapabilities);
//        Toast.makeText(context, "onCapabilitiesChanged", Toast.LENGTH_SHORT).show();
            }

            /**
             * 當(dāng)建立網(wǎng)絡(luò)連接時(shí)，回調(diào)連接的屬性
             */
            @Override
            public void onLinkPropertiesChanged(Network network, LinkProperties linkProperties) {
                super.onLinkPropertiesChanged(network, linkProperties);
//        Toast.makeText(context, "onLinkPropertiesChanged", Toast.LENGTH_SHORT).show();
            }

            /**
             * 按照官方注釋的解釋，是指如果在超時(shí)時(shí)間內(nèi)都沒有找到可用的網(wǎng)絡(luò)時(shí)進(jìn)行回調(diào)
             */
            @Override
            public void onUnavailable() {
                super.onUnavailable();
//        Toast.makeText(context, "onUnavailable", Toast.LENGTH_SHORT).show();
            }
        };
    }

    private static class SingletonHolder {
        /**
         * 靜態(tài)初始化器，由JVM來保證線程安全
         */
        public static final NetworkCallbackImpl INSTANCE = new NetworkCallbackImpl();
    }

    public static NetworkCallbackImpl getInstance() {
        return SingletonHolder.INSTANCE;
    }

    /**
     * 在application中調(diào)用
     */
    public void register(Context context) {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
            NetworkRequest.Builder builder = new NetworkRequest.Builder();
            NetworkRequest request = builder.build();
            ConnectivityManager mConnectivityManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
            // 請注意這里會有一個(gè)版本適配bug，所以請?jiān)谶@里添加非空判斷
            if (mConnectivityManager != null) {
                mConnectivityManager.registerNetworkCallback(request, networkCallback);
            }
        }
    }

    public void addNetworkCallback(Object tag, NetworkCallbackUtil.ConnectivityChangeCallback call) {
        callbackList.put(tag, call);
    }

    public void removeNetworkCallback(Object tag) {
        callbackList.remove(tag);
    }

}

BroadcastReceiver類：

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;

import java.util.HashMap;
import java.util.Map;

public class NetworkChangBroadcast {
    private BroadcastReceiver mNetworkChangBroadcast;
    private Map<Object, NetworkCallbackUtil.ConnectivityChangeCallback> callbackList = new HashMap<>();

    private static class SingletonHolder {
        static final NetworkChangBroadcast INSTANCE = new NetworkChangBroadcast();
    }

    public static NetworkChangBroadcast getInstance() {
        return NetworkChangBroadcast.SingletonHolder.INSTANCE;
    }

    private NetworkChangBroadcast() {
        mNetworkChangBroadcast = new BroadcastReceiver() {
            @Override
            public void onReceive(Context context, Intent intent) {
                ConnectivityManager connectivityManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
                NetworkInfo networkInfo = connectivityManager.getActiveNetworkInfo();
                if (networkInfo != null && networkInfo.isAvailable()) {
//            Toast.makeText(context, "網(wǎng)絡(luò)已連接", Toast.LENGTH_SHORT).show();
                    for (NetworkCallbackUtil.ConnectivityChangeCallback callback : callbackList.values()) {
                        callback.onAvailable(null, networkInfo);
                    }
                } else {
//            Toast.makeText(context, "網(wǎng)絡(luò)斷開", Toast.LENGTH_SHORT).show();
                    for (NetworkCallbackUtil.ConnectivityChangeCallback callback : callbackList.values()) {
                        callback.onLost(null, networkInfo);
                    }
                }
            }
        };
    }

    public void register(Context context) {
        IntentFilter intentFilter = new IntentFilter();
        intentFilter.addAction("android.net.conn.CONNECTIVITY_CHANGE");
        context.registerReceiver(mNetworkChangBroadcast, intentFilter);
    }

    public void unregister(Context context) {
        context.unregisterReceiver(mNetworkChangBroadcast);
    }

    public void addNetworkCallback(Object tag, NetworkCallbackUtil.ConnectivityChangeCallback call) {
        callbackList.put(tag, call);
    }

    public void removeNetworkCallback(Object tag) {
        callbackList.remove(tag);
    }


}

使用示例：
1,所需權(quán)限：

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

2,,在applicationg中進(jìn)行注冊

 @Override
    public void onCreate() {
        super.onCreate();
        NetworkCallbackUtil.register(this);
    }

3,在基礎(chǔ)Activity類中，添加和移除監(jiān)聽接口：

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        NetworkCallbackUtil.addNetworkCallback(this.getClass().getName(), new NetworkCallbackUtil.ConnectivityChangeCallback() {
            @Override
            public void onAvailable(Network network, NetworkInfo networkInfo) {
             //網(wǎng)絡(luò)可用的回調(diào)
            }

            @Override
            public void onLost(Network network, NetworkInfo networkInfo) {
              //網(wǎng)絡(luò)丟失的回調(diào)
            }
        });
    }

@Override
    protected void onDestroy() {
        super.onDestroy();
        NetworkCallbackUtil.removeNetworkCallback(this.getClass().getName());
    }

后言感謝：

android 5.0 以上監(jiān)聽網(wǎng)絡(luò)變化
Android 7.0 監(jiān)聽網(wǎng)絡(luò)變化的示例代碼
Android監(jiān)聽網(wǎng)絡(luò)變化練習(xí)（1）
Android實(shí)時(shí)監(jiān)聽網(wǎng)絡(luò)的變化