自定义广播监听网络状态

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.support.v7.app.AlertDialog;

import static android.content.Context.CONNECTIVITY_SERVICE;
import static android.net.ConnectivityManager.TYPE_WIFI;
import static android.provider.ContactsContract.CommonDataKinds.Phone.TYPE_MOBILE;

public class NetWord extends BroadcastReceiver {


    private Context context;

    @Override
    public void onReceive(Context context, Intent intent) {
        this.context = context;
        ConnectivityManager connectionManager = (ConnectivityManager) context.getSystemService(CONNECTIVITY_SERVICE);
        NetworkInfo networkInfo = connectionManager.getActiveNetworkInfo();
        if (networkInfo != null && networkInfo.isAvailable()) {
            switch (networkInfo.getType()) {
                case TYPE_MOBILE:
                    showPop(1);
                    break;
                case TYPE_WIFI:
                    showPop(2);
                    break;
                default:
                    break;
            }
        } else {
            showPop(3);
        }
    }

    private void showPop(int type) {
        switch (type) {
            case 1:
                myPop("正在使用2G/3G/4G网络");
                break;
            case 2:
                myPop("正在使用wifi上网");
                break;
            case 3:
                myPop("当前无网络连接");
                break;
        }
    }

    public void myPop(String state) {
        AlertDialog.Builder builder = new AlertDialog.Builder(context);
        builder.setMessage(state);

        //设置正面按钮
        builder.setPositiveButton("是的", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                dialog.dismiss();
            }
        });

        //设置反面按钮
        builder.setNegativeButton("取消", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                dialog.dismiss();
            }
        });
        builder.show();

    }


}

        在监听的Activity的onCreate方法中注册
         IntentFilter intentFilter = new IntentFilter();
        intentFilter.addAction("android.net.conn.CONNECTIVITY_CHANGE");
        //提成成员变量
        networkChangeReceiver = new NetWord();  //这个是自己写的广播接收者
        registerReceiver(networkChangeReceiver, intentFilter);
        

        在OnDestory方法中销毁
         unregisterReceiver(networkChangeReceiver);