全局dialog

public static void PttDialog(Context context){    if(dialog != null && dialog.isShowing())    {        return;    }    AlertDialog.Builder builder = new AlertDialog.Builder(context);    builder.setTitle("本机正在讲话");    dialog = builder.create();    builder.setCancelable(false);    dialog.getWindow().setType(WindowManager.LayoutParams.TYPE_SYSTEM_ALERT);//系统级别的dialog    dialog.setCanceledOnTouchOutside(false);//失去焦点不会消失    dialog.show();}