WIFI检测--对话框

public static boolean isWifi(Context context) {
    ConnectivityManager connectivityManager = (ConnectivityManager) context
            .getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo activeNetInfo = connectivityManager.getActiveNetworkInfo();
    if (activeNetInfo != null
            && activeNetInfo.getType() == ConnectivityManager.TYPE_WIFI) {
        return true;
    }
    return false;
}

使用：

if (!mIsWifi) {
    AlertDialog.Builder builder = new AlertDialog.Builder(this);
    builder.setMessage("初次使用会从网络下载大概5MB的图片，确认要下载吗？");
    builder.setTitle("注意");
    builder.setPositiveButton("是", new OnClickListener() {
        @Override
        public void onClick(DialogInterface dialog, int which) {
            mCanGetBitmapFromNetWork = true;
            mImageAdapter.notifyDataSetChanged();
        }
    });
    builder.setNegativeButton("否", null);
    builder.show();
}