广播接受者判断网络连接状态

public class ConnectionChangeReceiver extends BroadcastReceiver {
private AlertDialog alertDialog;
//标记的作用是为了避免对话框弹出多次
private boolean isConnect = false;//标记是否连接
private boolean isGPRS = false;//标记连接方式是移动网络
private boolean isWifi = false;//标记连接方式是wifi

@Override
public void onReceive(final Context context, Intent intent) {

ConnectivityManager cm = (ConnectivityManager) context.getSystemService(Service.CONNECTIVITY_SERVICE);
NetworkInfo networkInfo = cm.getActiveNetworkInfo();
//无网络状态
if(networkInfo == null || !networkInfo.isConnected()){
if(isConnect){
alertDialog = new AlertDialog(context).builder();
alertDialog.setTitle("已关闭移动数据");
alertDialog.setMsg("您可以在“设置”中为此应用打开移动数据。");
alertDialog.setPositiveButton("好", new View.OnClickListener() {
@Override
public void onClick(View v) {

}
});
alertDialog.setNegativeButton("设置", new View.OnClickListener() {
@Override
public void onClick(View v) {
context.startActivity(new Intent(Settings.ACTION_DATA_ROAMING_SETTINGS));
}
});
LogHelp.i("dialog","dialog1");
isGPRS = false;
isWifi = false;
isConnect = false;
alertDialog.show();
}
}else if (networkInfo != null && networkInfo.getType() == ConnectivityManager.TYPE_MOBILE) {
if(!isGPRS){
//只有GPRS，没有wifi的状态
alertDialog = new AlertDialog(context).builder();
alertDialog.setTitle("流量使用提示");
alertDialog.setMsg("当前网络无Wi-Fi，继续播放可能会被运营商收取流量费用");
alertDialog.setPositiveButton("继续播放", new View.OnClickListener() {
@Override
public void onClick(View v) {

}
});
alertDialog.setNegativeButton("停止播放", new View.OnClickListener() {
@Override
public void onClick(View v) {

}
});
LogHelp.i("dialog", "dialog2");
isWifi = false;
isGPRS = true;
isConnect = true;
alertDialog.show();
}
}else if(networkInfo != null && networkInfo.getType() == ConnectivityManager.TYPE_WIFI){
if(!isWifi){
LogHelp.i("dialog", "dialog3");
isGPRS = false;
isConnect = true;
isWifi = true;
}
}
}
}