public class MainActivity extends Activity {
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    ConnectivityManager nw = (ConnectivityManager)this.getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo netinfo = nw.getActiveNetworkInfo();
    Toast.makeText(MainActivity.this, "当前网络"+add(netinfo.isAvailable())+","+"网络"+app(netinfo.isConnected())+","+"网络连接"+adp(netinfo.isConnected()), Toast.LENGTH_LONG).show();//给用户提示网络状态
  }
  String add(Boolean bl){
    String s = "不可用";
    if(bl==true){
      s="可用";
    }
    return s;
  }
  String app(Boolean bl){
    String s = "未连接";
    if(bl==true){
      s="已连接";
    }
    return s;
  }
  String adp(Boolean bl){
    String s = "不存在！";
    if(bl==true){
      s="存在！";
    }
    return s;
  }  
}

<!-- 获得网络权限 -->
  <uses-permission 
    android:name="android.permission.ACCESS_NETWORK_STATE"
    />