1. public class MainActivity extends AppCompatActivity{
2.
3. private IntentFilter intentFilter;
4.
5. private NetWorkChangeReceiver netWorkChangeReceiver;
6.
7. @Override
8. protected void onCreate(Bundle savedInstanceState){
9. super.Oncreata(savedInstanceState);
10. setContentView(R.layout.activity_main);
11.
12. intentFilter = new IntentFilter();
13. intentFilter.addAction("android.net.conn.CONNECTIVITY_CHANGE");
14. networkChangeReceiver = new NetWorkChangeReceiver();
15. registerReceiver(networkChangeReceiver, intentFilter);//注册广播接收
器
16.
17. }
18.
19. @Overrid
20. protected void onDestroy(){
21. unregisterReceiver(networkChangeReceiver);//一定要记得取消广播接收器的
注册
22. super.onDestroy();
23.
24. }
25.
26. class NetworkChangeReceiver extends BroadcastReceiver{//广播接收器类
27.
28. @Override
29. public void onReceiver(Context context,Intent intent){
30.
31. //这里需要权限，需要在 AndroidManifest.xml 中进行网络访问权限申请:
32. //<usespermission android:name="android.permission.ACCESS_NETWORK_STATE"/>
33. ConnectivityManager connectionManager = (ConnectivityManager)
34. getSystemService(Context.CONNECTIVITY_SERVICE);
35. NetworkInfo networkInfo = connectionManager.getActiveNetworkInfo
();
36.
37. if (networkInfo != null && networkInfo.isAvailable()) {
38.
39. //有网
40. Toast.makeText(context, "network is available",Toast.LENGT
H_SHORT).show();
41.
42. } else {
43.
44. //无网
45. Toast.makeText(context, "network is unavailable",
46. Toast.LENGTH_SHORT).show();
47. }
48. }
49.
50. }
51.
52.
53. }