监听网络变化在开发中是经常用到的，例如我们断网有一些友好的提示，或者根据不同的网络更改一些加载策略，例如wifi看视频，非wifi则会有一个提示，等等情况。
在5.0以前，我们都是广播BroadcastReceiver，注册跟网络变化相关的广播，然后判断是连接还是断开，这种做法非常方便，但是随着安卓的版本迭代，在权限上越来越谨慎，广播的方式就显得不太优雅。
所以在安卓5.0以上终于对网络的监听进行了优化，那就是通过Callback回调的方式，这种开发模式是不是很常用？例如监听下载进度，我只需要三个回调：下载成功，下载失败，下载的进度变化，这种回调方式针对性强，耦合性低，非常方便。
为此我借鉴了大牛们的一些做法以及代码，写了一点东西，希望5.0之前和之后都能兼容到。
主要涉及到三个核心类：
代码如下：
NetworkCallbackUtil.java
import android.content.Context;
import android.net.Network;
import android.net.NetworkInfo;
import android.os.Build;
/**
* 监听网络连接状态
* 主要作用类还是 NetworkCallbackImpl
*/
public class NetworkCallbackUtil {
/**
* 在application中调用
*/
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);
}
}
/**
* 网络状态监听接口
* 可模仿ConnectivityManager.NetworkCallback的接口方法（在NetworkCallbackImpl中），目前只用到两个
* 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() {
/**
* 网络可用的回调
*/
@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);
}
}
/**
* 在网络失去连接的时候回调，但是如果是一个生硬的断开，他可能不回调
*/
@Override
public void onLosing(Network network, int maxMsToLive) {
super.onLosing(network, maxMsToLive);
// Toast.makeText(context, "onLosing", Toast.LENGTH_SHORT).show();
}
/**
* 网络丢失的回调
*/
@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，当我们的网络的某个能力发生了变化回调，那么也就是说可能会回调多次
* <p>
* 之后在仔细的研究
*/
@Override
public void onCapabilitiesChanged(Network network, NetworkCapabilities networkCapabilities) {
super.onCapabilitiesChanged(network, networkCapabilities);
// Toast.makeText(context, "onCapabilitiesChanged", Toast.LENGTH_SHORT).show();
}
/**
* 当建立网络连接时，回调连接的属性
*/
@Override
public void onLinkPropertiesChanged(Network network, LinkProperties linkProperties) {
super.onLinkPropertiesChanged(network, linkProperties);
// Toast.makeText(context, "onLinkPropertiesChanged", Toast.LENGTH_SHORT).show();
}
/**
* 按照官方注释的解释，是指如果在超时时间内都没有找到可用的网络时进行回调
*/
@Override
public void onUnavailable() {
super.onUnavailable();
// Toast.makeText(context, "onUnavailable", Toast.LENGTH_SHORT).show();
}
};
}
private static class SingletonHolder {
/**
* 静态初始化器，由JVM来保证线程安全
*/
public static final NetworkCallbackImpl INSTANCE = new NetworkCallbackImpl();
}
public static NetworkCallbackImpl getInstance() {
return SingletonHolder.INSTANCE;
}
/**
* 在application中调用
*/
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);
// 请注意这里会有一个版本适配bug，所以请在这里添加非空判断
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类：
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, "网络已连接", Toast.LENGTH_SHORT).show();
for (NetworkCallbackUtil.ConnectivityChangeCallback callback : callbackList.values()) {
callback.onAvailable(null, networkInfo);
}
} else {
// Toast.makeText(context, "网络断开", 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,所需权限：
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE"/>
2,,在applicationg中进行注册
@Override
public void onCreate() {
super.onCreate();
NetworkCallbackUtil.register(this);
}
3,在基础Activity类中，添加和移除监听接口：
@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) {
//网络可用的回调
}
@Override
public void onLost(Network network, NetworkInfo networkInfo) {
//网络丢失的回调
}
});
}
@Override
protected void onDestroy() {
super.onDestroy();
NetworkCallbackUtil.removeNetworkCallback(this.getClass().getName());
}
后言感谢：
android 5.0 以上监听网络变化
Android 7.0 监听网络变化的示例代码
Android监听网络变化练习（1）
Android实时监听网络的变化
