Android異步任務中的網絡狀態監聽

在Android中，我們可以使用ConnectivityManager來監聽網絡狀態變化。以下是一個簡單的示例，展示了如何在異步任務中監聽網絡狀態：

1. 首先，創建一個名為NetworkStateReceiver的廣播接收器，用于接收網絡狀態變化的事件：

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;

public class NetworkStateReceiver extends BroadcastReceiver {
    private OnNetworkStateChangeListener listener;

    public void setOnNetworkStateChangeListener(OnNetworkStateChangeListener listener) {
        this.listener = listener;
    }

    @Override
    public void onReceive(Context context, Intent intent) {
        if (intent.getAction().equals(ConnectivityManager.CONNECTIVITY_ACTION)) {
            ConnectivityManager connectivityManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
            NetworkInfo networkInfo = connectivityManager.getActiveNetworkInfo();
            boolean isConnected = networkInfo != null && networkInfo.isConnectedOrConnecting();
            if (listener != null) {
                listener.onNetworkStateChanged(isConnected);
            }
        }
    }

    public interface OnNetworkStateChangeListener {
        void onNetworkStateChanged(boolean isConnected);
    }
}

2. 在你的異步任務類中，注冊并監聽網絡狀態變化：

import android.content.Context;
import android.content.IntentFilter;
import android.os.AsyncTask;

public class MyAsyncTask extends AsyncTask<Void, Void, Void> {
    private Context context;
    private NetworkStateReceiver networkStateReceiver;

    public MyAsyncTask(Context context) {
        this.context = context;
    }

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        registerNetworkStateReceiver();
    }

    @Override
    protected Void doInBackground(Void... voids) {
        // 在這里執行你的異步任務
        return null;
    }

    @Override
    protected void onPostExecute(Void aVoid) {
        super.onPostExecute(aVoid);
        unregisterNetworkStateReceiver();
    }

    private void registerNetworkStateReceiver() {
        networkStateReceiver = new NetworkStateReceiver();
        networkStateReceiver.setOnNetworkStateChangeListener(new NetworkStateReceiver.OnNetworkStateChangeListener() {
            @Override
            public void onNetworkStateChanged(boolean isConnected) {
                // 在這里處理網絡狀態變化
            }
        });
        IntentFilter intentFilter = new IntentFilter();
        intentFilter.addAction(ConnectivityManager.CONNECTIVITY_ACTION);
        context.registerReceiver(networkStateReceiver, intentFilter);
    }

    private void unregisterNetworkStateReceiver() {
        if (networkStateReceiver != null) {
            context.unregisterReceiver(networkStateReceiver);
            networkStateReceiver = null;
        }
    }
}

現在，當網絡狀態發生變化時，onNetworkStateChanged方法將被調用，你可以在這里處理網絡狀態變化。請注意，不要忘記在異步任務結束時取消注冊廣播接收器。