网络状态判断

public class MainActivity extends AppCompatActivity {


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);


        //得到管理者
        ConnectivityManager manager= (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
        //得到链接信息对象
        NetworkInfo networkInfo = manager.getActiveNetworkInfo();
        //进行网络判断
        if (networkInfo!=null&&networkInfo.isConnected()){


            Toast.makeText(MainActivity.this,"网络连上了",Toast.LENGTH_LONG).show();


        }else{
            Toast.makeText(MainActivity.this,"网络断开了",Toast.LENGTH_LONG).show();
        }
    }

}

//添加权限

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