这只检查网络接口是否可用，并不保证特定的网络服务可用，例如，可能有低信号或服务器停机
private boolean isNetworkInterfaceAvailable(Context context) {
ConnectivityManager cm = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo activeNetwork = cm.getActiveNetworkInfo();
return activeNetwork != null && activeNetwork.isConnectedOrConnecting();
}
如果你想建立一个真正的连接，以确保你的连接可以从服务器或任何url收集数据:
private boolean isAbleToConnect(String url, int timeout) {
try {
URL myUrl = new URL(url);
URLConnection connection = myUrl.openConnection();
connection.setConnectTimeout(timeout);
connection.connect();
return true;
} catch (Exception e) {
Log.i("exception", "" + e.getMessage());
return false;
}
}
这个函数需要被包装在后台线程中:
final String action = intent.getAction();
if (intent.getAction().equals(ConnectivityManager.CONNECTIVITY_ACTION)) {
checkConnectivity(context);
}
}
private void checkConnectivity(final Context context) {
if (!isNetworkInterfaceAvailable(context)) {
Toast.makeText(context, "You are OFFLINE!", Toast.LENGTH_SHORT).show();
return;
}
final Handler handler = new Handler();
new Thread(new Runnable() {
@Override
public void run() {
final boolean isConnected = isAbleToConnect("http://www.google.com", 1000);
handler.post(new Runnable() {
@Override
public void run() {
if (isConnected)
Toast.makeText(context, "You are ONLINE!", Toast.LENGTH_SHORT).show();
else
Toast.makeText(context, "You are OFFLINE!", Toast.LENGTH_SHORT).show();
}
});
}
}).start();
}
添加所需权限:
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.INTERNET"/>
在manifest文件的application下添加以下一行:
android:usesCleartextTraffic="true"
将接收者添加到清单文件:
<receiver android:name=".ConnectivityChangeReceiver" >
<intent-filter>
<action android:name="android.net.conn.CONNECTIVITY_CHANGE" />
</intent-filter>
</receiver>
在活动中注册/取消注册BR:
@Override
protected void onStart() {
super.onStart();
IntentFilter filter = new IntentFilter("android.net.conn.CONNECTIVITY_CHANGE");
registerReceiver(connectivityChangeReceiver, filter);
}
@Override
protected void onDestroy() {
super.onDestroy();
unregisterReceiver(connectivityChangeReceiver);
}
这是整个Broadcast类:
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.Handler;
import android.util.Log;
import android.widget.Toast;
import java.net.URL;
import java.net.URLConnection;
public class ConnectivityChangeReceiver extends BroadcastReceiver {
@Override
public void onReceive(final Context context, final Intent intent) {
final String action = intent.getAction();
if (intent.getAction().equals(ConnectivityManager.CONNECTIVITY_ACTION)) {
checkConnectivity(context);
}
}
private void checkConnectivity(final Context context) {
if (!isNetworkInterfaceAvailable(context)) {
Toast.makeText(context, "You are OFFLINE!", Toast.LENGTH_SHORT).show();
return;
}
final Handler handler = new Handler();
new Thread(new Runnable() {
@Override
public void run() {
final boolean isConnected = isAbleToConnect("http://www.google.com", 1000);
handler.post(new Runnable() {
@Override
public void run() {
if (isConnected)
Toast.makeText(context, "You are ONLINE!", Toast.LENGTH_SHORT).show();
else
Toast.makeText(context, "You are OFFLINE!", Toast.LENGTH_SHORT).show();
}
});
}
}).start();
}
//This only checks if the network interface is available, doesn't guarantee a particular network service is available, for example, there could be low signal or server downtime
private boolean isNetworkInterfaceAvailable(Context context) {
ConnectivityManager cm = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo activeNetwork = cm.getActiveNetworkInfo();
return activeNetwork != null && activeNetwork.isConnectedOrConnecting();
}
//This makes a real connection to an url and checks if you can connect to this url, this needs to be wrapped in a background thread
private boolean isAbleToConnect(String url, int timeout) {
try {
URL myUrl = new URL(url);
URLConnection connection = myUrl.openConnection();
connection.setConnectTimeout(timeout);
connection.connect();
return true;
} catch (Exception e) {
Log.i("exception", "" + e.getMessage());
return false;
}
}
}
