如何停止异步任务时，互联网连接，但没有互联网访问android

Question

String url = "http://xyzcloud.com/xyz/xyz.php";

这是我试图从云端获取数据的url，如果互联网已连接，则将执行异步任务。我编写了此方法，用于检查互联网是否已连接，在我的移动wifi中，当我尝试执行时，出现异常

public boolean checkOnlineState()
    {
        boolean val = false;
        ConnectivityManager CManager = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
        NetworkInfo NInfo = CManager.getActiveNetworkInfo();
        if (NInfo != null && NInfo.isConnectedOrConnecting()) {
            try {
                if (InetAddress.getByName(url).isReachable(10000))
                {
                    // host reachable
                    val=true;
                    Log.e("checkOnlineState", "" + val);
                }
                else
                {
                    // host not reachable
                    val = false;
                    Log.e("checkOnlineState", "" + val);
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        return val;
    }

Answer 1

import android.app.Service;
import android.content.Context;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;

public class ConnectionDetector {

    private Context context;

    public ConnectionDetector(Context context) {

        this.context = context;
    }

    public boolean isConnected() {

        ConnectivityManager connectivity = (ConnectivityManager) context.getSystemService(Service.CONNECTIVITY_SERVICE);

        if ( connectivity != null) {

            NetworkInfo info = connectivity.getActiveNetworkInfo();

            if (info != null) {

                if (info.getState() == NetworkInfo.State.CONNECTED) {

                    return true;
                }
            }
        }

        return false;
    }
}

例如，您可以利用它：

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        ConnectionDetector cd = new ConnectionDetector(this);

        if (cd.isConnected()) {
            // do something
        } else {
            //do something
        }

        setContentView(R.layout.activity_main);
    }
}

我在我的应用程序中使用这种方法（需要Internet连接），并且还没有遇到任何问题。